Thursday, January 27, 2011

Vegetables Are Nutritionally Useless? Try Again Zoe.

Zoe Harcombe, a Cambridge graduate currently studying for a PhD in nutrition, wrote a piece for Mail Online  in which she claims that vegetables and fruits are nutritionally useless.  I consider it worthwhile to examine her “argument” carefully. Here we go:

“People are convinced that fruit and vegetables are a particularly good source of vitamins and minerals.

“For a long time, I too was a believer. I was a vegetarian for 20 years. It is only after nearly two decades of my own research — I am a Cambridge graduate and currently studying for a PhD in nutrition —that I have changed my views.”

Nice stab at an appeal to your own authority. It does not matter to me whether you graduated from Cambridge or taught yourself, and I don’t care about PhDs either, only care whether you use facts and logic properly. I was also a vegetarian for many years, no longer, but being a vegetarian doesn’t make you knowledgable about nutrition or vegetables either.

“The message that fruit and veg are pretty useless, nutritionally, gradually dawned on me.”

Zoe, you can’t rationally talk about the nutritional content of fruits and vegetables generically, because they—particularly vegetables—vary too much in nutrient content.  Its like saying that motorized vehicles are “pretty useless” for traveling to the moon—which motorized vehicles are you talking about?  There's a vast difference in nutrient density between zucchini and collards. Think, Zoe, think.

“The facts are these. There are 13 vitamins and fruit is good for one of them, vitamin C.

“Vegetables offer some vitamins — vitamin C and the vegetable form of the fat-soluble vitamins A and vitamin K1 — but your body will be able to absorb these only if you add some fat, such as butter or olive oil.

“The useful forms of A and K — ­retinol and K2 respectively — are found only in animal foods. As for minerals, there are 16 and fruit is good for one of them, potassium, which is not a substance we are often short of, as it is found in water.”

Whoa….hold on Zoe. The you just said that fruit is "pretty useless," then you say it is good for vitamin C. You can’t have it both ways, both useless and useful. Then, the fact that you need to have some fat with vegetables to absorb carotenoids and K1 does not make vegetables useless. This is like saying that autos are useless because you have to fill them with gasoline to make them work.  Perhaps you forgot that you also have to consume fat with retinol and K2 as well, putting them in that respect on par with K1 and carotenoids.

Next, you state that carotenes and vitamin K2 are the useful form of the A and the K complex, implying that K1 is not useful, which is simply wrong. We need K1 for normal blood clotting function. Moreover, it appears that vitamin K1 can protect arterial elasticity . As for carotenes, perhaps you consider them useless, but I don’t feel so certain, since humans accumulate carotenes in various tissues, they appear associated across species with longevity,  we have evidence that they provide photoprotection, and may have roles in fertility and breast health.

“Vegetables can be OK for iron and calcium but the vitamins and minerals in animal foods (meat, fish, eggs and dairy products) beat those in fruit and vegetables hands down. There is far more vitamin A in liver than in an apple, for instance.”

Again you contradict yourself, after saying vegetables are “pretty useless, nutritionally” you admit that they contain iron and calcium. Then you set up a straw man argument by comparing apples, which contain no vitamin A, to liver, which does contain vitamin A. Since you assert that meat, fish, eggs, and dairy products beat “fruit and vegetables hands down,” let’s compare collards and beef sirloin on a gram for gram basis, first for vitamins:

Click for larger version


• Collards excel in folate (10:1), vitamin C, provitamin A (as carotenoids) , vitamin K1 (400:1), and vitamin E (almost 2:1).
• Beef excels in B1 (1.5:1), B2 (1.2:1), B3 (12:1), B5 (2.4:1), choline (~3:1), B6 (~4:1), and B12.
• Of 12 vitamins, collards excels in 5, beef sirloin in 7.
• Where collards excel, they do so by greater margins than by where sirloin excels.

Consider that the beef supplies nearly 10 times the caloric value of the collards, which means the nutrient density of collards relative to caloric content far exceeds that of beef. Thus, looking at vitamins, I find it hard to dismiss “vegetables” as nutritionally useless. Collards provide far more folate, vitamin C, K1, and E than beef, as well as carotenoids which may or may not have vitamin A value depending on the genetic constitution of the consumer, but which in any case may have functions in photoprotection and fertility. Although we absorb only about 10% of K1 in vegetables if consumed with fat, discounting the K1 in collards by 90% they still deliver amost 30 times more K1 than beef sirloin.

Now for minerals:
Click for larger version


• Collards excel in calcium (8:1) and manganese (44:1).
• Beef clearly excels in iron (1.5:1), phosphorus (almost 7:1), potassium (about 2:1), zinc (20:1), copper (>2:1), and selenium (60:1).
• The value for magnesium is not significantly different (beef:collards = 1.1:1)

Thus, collards equal or exceed beef sirloin as a source of calcium, magnesium, and manganese, while beef provides more iron, etc. Again, I don’t see how one can say that “vegetables” are nutritionally useless compared to animal products until you specify which vegetables and which animal products you want to compare.

If you compare kale and beef sirloin on a calorie for calorie basis, you find something even more remarkable:
Click on image for larger version

So kcalorie for kcalorie kale provides:

• 93 times more calcium

• twice as much iron

• 3.75 times as much magnesium

• five times as much potassium,

• 2486 more units of provitamin A activity (mostly in humans not forming A, but used as carotenoids)

• 2.4 times as much thiamin

• 44 times as much vitamin E

• almost ten times as much folate

• and 86 mg more vitamin C.

If that makes kale nutritionally useless, I don’t know what would make it useful.

If I compared these greens to eggs, milk, liver, or any other animal product, the results would be different.  I'm not claiming that vegetables are superior to animal products, only argue against the headline grabbing claim that vegetables are "pretty useless." 

Comparing apples to liver for vitamin A content makes you, Zoe, look like the inverse of the vegetarians who attack animal products for not supplying fiber and carbohydrates.  Apples aren't useless because they don't provide retinol, and liver isn't useless because it doesn't have fiber or much vitamin C.   Jets aren't useless because you can't drive them on highways, and cars aren't useless because they don't fly. 

“But surely, people ask, even if there is no evidence that increasing our intake of fruit and vegetables will help prevent disease, they remain good things to eat?

“I don’t think so. If people try to add five portions of fruit and veg — let alone eight — a day to their diet, it can be counterproductive. Fruit contains high levels of fructose, or fruit sugar.

“Among dieticians, fructose is known as ‘the fattening carbohydrate’. It is not metabolised by the body in the same way as glucose, which enters the bloodstream and has a chance to be used for energy before it heads to the liver.

“Fructose goes straight to the liver and is stored as fat. Very few people understand or want to believe this biochemical fact.”

Here’s another straw man. One can easily eat 5 portions of vegetables daily (2.5 cups cooked) and avoid your dreaded fructose. Further, the statement “Fructose goes straight to the liver and is stored as fat” is out of context, namely the context of energy expenditure. It will only be stored as fat if that fat is not needed for use as energy.

“Another argument that is often put forward by dieticians on behalf of fruit and vegetables is that they are ‘a source of antioxidants’.”

Funny, just above you are quoting dieticians as the supreme source of knowledge on the metabolism of fructose, but now you put them downs as stupid for believing in plant foods as sources of antioxidants.

Tell us more:

“The biggest tragedy of all is the lost opportunity from this misguided five-a-day campaign.

“If only we had hand-picked the five foodstuffs that are actually most nutritious and spent what the Department of Health has spent on promoting fruit and vegetables over the past 20 years on recommending them, we could have made an ­enormous difference to the health and weight of our nation.

“If you ask me, these foodstuffs are liver (good for all vitamins and packed with minerals), sardines (for vitamin D and calcium), eggs (all-round super-food with vitamins A, B, D, E and K, iron, zinc, calcium and more), sunflower seeds (magnesium, vitamin E and zinc) and dark-green vegetables such as broccoli or spinach (for vitamins C, K and iron).”

WHAT? Zoe, you started this article telling us that vegetables aren’t good sources of vitamins or minerals, and said that K1 in vegetables is useless, and then you even implied that they aren't even "good to eat," but now you tell us we should eat dark-green vegetables of vitamins C, K(1), and iron? Give me a break. You clearly attacked “vegetables” just to grab a headline.

You haven't given me a very good impression of Cambridge graduates or whatever PhD (piled high and dry?) program you're completing.  Try again Zoe.

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Tuesday, January 25, 2011

Study: People Prefer The Carotene Complexion Over The Sun Tan On Evolutionary Basis

Science News reports on an interesting study published in the Journal of Evolution and Human Behavior which found that people prefer the glow of skin that results from eating foods rich in carotenoids over the darker coloration produced by a sun tan.

Left, sun tan; center, neutral; right, carotene-rich
According to the Science News article:

“Dr Ian Stephen, from the School of Psychology, University of Nottingham, Malaysia Campus, led the research as part of his PhD at the University of St Andrews and Bristol University. He said: "Most people think the best way to improve skin colour is to get a suntan, but our research shows that eating lots of fruit and vegetables is actually more effective.”

The article continues:

“Dr Stephen said: ‘We found that, given the choice between skin colour caused by suntan and skin colour caused by carotenoids, people preferred the carotenoid skin colour, so if you want a healthier and more attractive skin colour, you are better off eating a healthy diet with plenty of fruit and vegetables than lying in the sun.’

“Dr Stephen suggests that the study is important because evolution would favour individuals who choose to form alliances or mate with healthier individuals over unhealthy individuals.

“Professor David Perrett, who heads the Perception Lab, said: ‘This is something we share with many other species. For example, the bright yellow beaks and feathers of many birds can be thought of as adverts showing how healthy a male bird is. What's more, females of these species prefer to mate with brighter, more coloured males. But this is the first study in which this has been demonstrated in humans.’”

This research follows up on the team’s previous publication in The International Journal of Primatology, entitled “Facial Skin Coloration Affects Perceived Health of Human Faces”  in which they discussed the health and fertility effects associated with carotenoid consumption and coloration in many species:

“Carotenoid supplementation is associated with improved development of the immune system in human children (Alexander et al. 1985), whereas individuals infected with HIV and malaria have reduced carotenoid levels (Friis et al. 2001). Carotenoid levels may also affect spermatogenesis in boars (Chew 1993), and women who failed to conceive during in vitro fertilization had unusually fluctuating carotenoid levels in their follicular fluid (Schweigert et al. 2003). Brightly colored carotenoid-based ornaments are displayed by many bird and fish species, the size and brightness of which reflect aspects of health and condition. Male greenfinches with brighter yellow breast feathers showed stronger humoral immune responses to a novel antigen (Saks et al. 2003). Male and female yellow-eyed penguins with more saturated yellow eye ornamentation produced more offspring per season (Massaro et al. 2003). Researchers have demonstrated mate choice based on the brightness of carotenoid ornaments in greenfinches (Eley 1991), yellow-eyed penguins (Massaro et al. 2003), and goldfinches (MacDougall and Montgomerie 2003).”

To summarize, the two studies simply show that people prefer (i.e. find more attractive) skin that has more red, yellow, and bright coloration, to skin that has blue, green, and dark coloration.  Stephen et al discuss the fact that redness signifies good blood perfusion, and that red, yellow, and bright coloration associates with fertility and virility in many species.  It appears that they have shown that this applies to humans as well as other species.  In case you wonder, they have also shown that people with naturally dark skin – namely, African ethnics – also prefer skin with a brighter, yellowish and reddish tint.

This research reminds me of earlier work published in the PNAS entitled “Carotenoids and retinol: their possible importance in determining longevity of primate species,”  (full text pdf available here ) in which Cutler showed that serum and brain tissue concentrations of carotenoids positively correlate with maximum life span potential in 13 mammalian species.  That is, he found that longer-lived species have higher serum and brain tissue carotenoid concentrations than short-lived species, with humans having the highest carotenoid concentrations of the 13 species he tested.  Cutler wrote:
“It is not understood what determines the serum and tissue concentrations of carotenoids, but it is likely to be based in part on the quantitative and qualitative aspects of absorption and on the activity of an enzyme found predominantly in the intestinal mucosa cells, ß-carotene 15,15'-dioxygenase (39). This enzyme is responsible for initiating the conversion of carotene to retinol, and low levels would be expected in the longer-lived species.
Indeed, humans do show lower activity of this enzyme; see below.  Continuing the quote from Cutler:
"Humans unselectively absorb both carotenes and xanthophylls into their tissues, whereas the shorter-lived species absorb only the carotenes (16-18). The amount of carotenoids in the diet would of course also play an important role in determining the amount of carotenoids that are absorbed, but not the qualitative aspects. Thus, although all carotenoids are derived from the diet, the amount and type that is absorbed in serum and other tissues is clearly a species-dependent characteristic. [italics added]

During the evolution of increased MLSP in the mammalian species, and particularly in the primates (27, 40), carotenoid concentration in serum and tissues also may have increased. This may have been facilitated by an increased absorption of both the carotenoids and xanthophyll and a decrease in the activity of intestinal ß-carotene 15,15'-dioxygenase.  Thus, the nonselective absorption of the carotenoids in humans may represent an end point to this evolutionary strategy; most of the carotenoid protection attainable through the diet is now being utilized.” [italics added]
It appears that in the course of human evolution, the activity of ß-carotene 15,15'-dioxygenase has declined substantially, such that up to 45% of people do not convert ß-carotene to retinol vitamin A. Hickenbottom et al   found that 45% of 11 men tested did not convert ß-carotene to vitamin A (retinol).  Lin et al  found the same in women. Leung et al identified gene polymorphisms contributing to this variability in carotene conversion capacity. 

These data indicate that in the course of our evolution, humans have shifted from use of ß-carotene as a precursor for vitamin A, to dependence upon animal sources of retinol (vitamin A), such as liver, exerting a negative pressure on the retention of activity of ß-carotene 15,15'-dioxygenase.  This simultaneously gave us opportunity to use carotenoids and xanthopylls for other purposes (as they were no longer needed for retinol production).  As noted by Cutler, we humans absorb these non-selectively, suggesting that the human organism has found uses for most carotenoids.  It appears that this shift facilitated an increase in lifespan, perhaps by virtue of the carotenoids now being available for use primarily as free-radical scavengers and protection against genetic malfunctions leading to cancer, etc.

As an example, consider the photoprotective effects of carotenoids.  You may have noticed that green leaves sit out in the sun all day long without any sunscreen, yet do not become cancerous regularly.  Aside from being a sign of health, the storage of carotenoids in the skin protects the skin from ultraviolet radiation thereby retarding the aging process.  For more support for this assertion, see this, this, this, this, this, and these:

These data appear to provide evidence similar to something I have noted in my experience, namely that a higher skin content of carotenoids may reduce both the tendency to burn and the need and production of melanin in response to UV radiation. When a youth and living in Ohio, I got sun burned many times in the summer sun there.  At the time, my diet had no where near the carotenoid levels of my current diet.  Now I live in Arizona, and I often go out in the blazing summer sun around noon.  In the 10 years I have lived in Arizona, I have never gotten a sun burn anything like I had when a child.  I might turn a little red on my shoulders for 24-36 hours, but I don’t blister and peel, despite the higher intensity of the Arizona sun compared to Ohio.  

Carotenoid Complexion and Sun Tan Not Mutually Exclusive

While Stephen et al may appear to consider sun tans and carotenoid complexion as mutually exclusive, as if one can only have one or the other, I would not agree with this.  Sun exposure is necessary for vitamin D production, not to be avoided.   

However, in my experience, copious consumption of carotenoid-rich food increases skin content of carotenoids to a level that leads to reduction of sun burning AND a reduced melanin response.  In all of the more than 20 years that I have eaten a high carotenoid content diet, my sun tan appears more orange-yellow than brown.

If you don’t believe that carotenoids can modify your response to sun exposure, both in terms of burning and melanin response, don’t look for more data.  I already gave you a dozen references above.  The next step is to try it yourself.  In my experience, even fair skinned (e.g. Scandinavian) individuals can increase their sun tolerance simply by increasing their intake of carotenoids.  Again, the best data comes from your own experience.  Try it. 

I believe that traditional consumption of high carotenoid content foods help explain why our ancestors could spend most of their time outdoors without suffering the type of malignant skin damage found among modern people who spend less time outdoors but consume lower amounts of carotenoids.  This is likely an aspect of dietary influence on skin cancer incidence.  Modern people may consume lower amounts of carotenoids than our ancestors, making modern man's skin more susceptible to sun damage despite less total sun exposure.

I further wonder if by eating both fatty meat and cooked or fermented carotenoid-rich vegetables (more about the cooked and fermented below), humans were able to reduce the use carotenoids for vitamin A and increase their use for photoprotection, which in turn reduced the need for body hair to protect the skin from UV radiation, as in other species.  In other words, I wonder if our unique approach to omnivory made it possible for us to shed most of our body hair and still withstand the African homeland sun.

Carotenoid Absorption and Sources

These authors emphasized eating fruits and vegetables for carotenoids.  However, they did not mention several important facts discussed at length in Carotenoids: Nutrition and Health :

  • Carotenoids are fat-soluble so we must consume fats with carotenoid-rich foods to optimize carotenoid absorption.  [p.136]
  • Fiber present in fruits and vegetables reduces carotenoid absorption:  
“Not only purified fibre, but also fruit and vegetables as sources of this fibre, cause reductions in carotenoid bioavailability.  Dietary fibre, lignin, and resistant proteins found in green leafy vegetables inhibited the release of ß-carotene and lutein [129] and citrus pectin reduced the plasma ß-carotene responses [126].” [p.138]

  • By rupturing plant cells in which carotenoids are stored, cooking and/or pureeing carotenoid-rich vegetables dramatically increases bioavailability of carotenoids. 
“In healthy women, feeding heat-processed and pureed carrots and spinach cause serum ß-carotene to be three times higher than when the same dietary level of ß-carotene was consume in the raw food sources [102].  In a population of women at risk for breast cancer, serum concentrations of lutein and a-carotene, but not of ß-carotene, ß-cryptoxanthin, or lycopene, were higher in women consuming vegetable juice, rather thatn cooked or raw vegetables [103].” [p.134]
  • Fake-fats (sucrose-polyesters) inhibit carotenoid absorption. [p.136]
  • Statin drugs and plant sterols reduce carotenoid absorption. [p.137]

Some people may suggest that animal fats from grass-finished animals supply substantial amounts of highly bioavailable carotenoids.   

  • Duckett et al found that meat from grass-finished cattle contains 54% more ß-carotene than meat from corn-finished animals. 
  • Mother Earth News reported that pastured chickens produce eggs that contain 7 times as much ß-carotene as conventional eggs.

This photo from my collection shows the difference in color between an egg yolk from a chicken fed a supplemented grain concentrate (purchased at a Wild Oats natural food store) and one from a chicken raised on pasture (purchased from A Bar H Farm), a difference caused by carotenoid concentration:

Egg yolks:  L, from grain-fed hen; R, from pastured hen.

However, these numbers and photos may mislead.  According to Duckett et al, conventional beef and grass-finished supply only 29 and 44 mcg ß-carotene per 100 g serving, respectively.  One pound of grass-finished beef thus provides about 200 mcg of ß-carotene. The Mother Earth News study found that one egg from a pastured hen supplies 79 mcg of ß-carotene.

 In comparison, 100 g of cooked carrots contains 8332 mcg of ß-carotene, more than 40 times what we could get from an entire pound of grass-finished beef.   Hedren et al produced data on absorption of carotenes from carrots suggesting a maximum extraction of about 3% of the ß-carotene if we eat it raw, and 39% if we cook the carrots to a soft texture and consume them with fat. 

The raw supplies less than the cooked, because in raw vegetables, all of the carotenoids lie inside the plant cell walls, which consist of cellulose, and we can't digest cellulose. Cooking explodes the cells, allowing the juice to flow out for utilization. 

Thus, 100 g of raw carrot would deliver  about 250 mcg of ß-carotene, 25% more than a whole pound of grass-finished beef and about 3 times as much as an egg yolk from a pastured egg.   One hundred grams of carrot cooked soft with fat would provide 3250 mcg of ß-carotene, more than 16 times what one would get from a whole pound of grass-finished beef, and 40 times what we could get from one egg yolk from a pastured hen.

Carotenoid-rich Primal Food:  Beef with carrots, squash, and greens.

Since it appears that people prefer carotenoid complexions (which in my experience can manifest in concert with a sun "tan"), and people with high blood levels of carotenoids have better health than those without, and this also occurs across ethnic groups as well as in other primate species, and high carotenoid levels of plasma and brain correlate with longevity across mammalian species, this strongly supports the idea that humans evolved to attain long lifespans on diets containing high amounts of both vitamin A and carotenoids, i.e. dark green leafy and deep orange or red vegetables or fruits such as kale, collards, spinach, carrots, winter squashes, and tomatoes, and not exclusively carnivorous diets. 

Ethnographic data (see Guts and Grease:  The Diet of Native Americans ) even largely carnivorous tribes of humans such as Inuit and Blackfoot recognized the value of deep green plant foods and got some carotenoids by consuming the partially fermented grasses found in the foreguts of ruminants such as buffalo and caribou.  As reported by Enig and Fallon  in "Guts and Grease," according to John (Fire) Lame Deer, the eating of guts in his tribe had evolved into a contest:

"In the old days we used to eat the guts of the buffalo, making a contest of it, two fellows getting hold of a long piece of intestines from opposite ends, starting chewing toward the middle, seeing who can get there first; that's eating. Those buffalo guts, full of half-fermented, half-digested grass and herbs, you did not need any pills and vitamins when you swallowed those." [1]
Again, I suggest you to test this in your own experience.  Dark green leafy vegetables and carrots have negligible carbohydrate content yet deliver large amounts of carotenoids.  If you are sun sensitive, or want to see how increasing the carotenoid content of your skin affects your sun tan or untanned appearance, all you have to do is eat more high carotenoid foods to find out.  It takes about 10 weeks of high carotenoid consumption to produce a change. 


1. John (fire) Lame Deer and Richard Erdoes, Lame Deer Seeker of Visions, Simon and Schuster, 1972, p. 122.

Friday, January 21, 2011

The Practically Primal Guide to Conventional Beef, Part 3: Nutritional composition

To reiterate, in this series of posts I only aim to discuss primarily whether or not conventional meats presents health risks to the consumer, not whether the methods used to raise conventional grain-fed meats produces the best environmental effects.  I have already discussed hormones in part I, and antibiotics and chemicals in part II. 

The next concern is the nutritional composition, including total fat content, fatty acid composition, omega-6 to omega-3 ratio, and vitamin and mineral content. 

Duckett et al compared the effect of grain- or grass- finishing systems on the nutritional composition of beef.  Comparing lean meat from grain- and grass- fed animals, they found that the grass-fed product had:

  • Increased moisture content
  • Decreased total lipid content by 43%
  • 288% greater vitamin E content
  • 54% greater b-carotene content
  • Twice as much riboflavin
  • Three times as much thiamin
  • 30% more calcium
  • 5% more magnesium
  • Roughly the same amount of omega-6 PUFA
  • Three times the omega-3 PUFA
  • Similar saturated fat content
  • 20% lower MUFA

Ducket et al found that grass-finished and grain-finished beef had, respectively, 1.65 and 4.84 times as much omega-6 as omega-3 fat, but, as noted, the absolute amount of omega-6 did not differ significantly between the two finishing strategies.  Thus, grain-feeding does not increase the omega-6 content, it only decreases the omega-3 content, of the meat.  This graph from shows the effect of grain-finishing on omega-3 content of meat from cattle:

Faucitano et al compared the effects of grain- or grass- finishing, either with or without hormonal growth promotants, on beef composition and palatability.  They raised all cattle to the same level of back fat deposition before slaughter, and found:

  • Meat from cattle fed grain and growth promotants had a tendency to appear dark in color whereas that from cattle fed grass had a more desired red color.
  • Meat from cattle given growth promotants tended to have a tougher texture.
  • Meat from grass-finished cattle was just as tender as grain-finished if allowed to grow to the same level of back fat deposition.
  • Types of feed did not alter omega-6 levels in meat
  • Meat from grass-finished animals given no growth promotants had about 50% more omega-6 fatty acids than animals given growth promotants regardless of feed type.
  • The more grain given to animals, the lower their omega-3 content of their meat, in a dose-dependent fashion (same finding as Ducket et al above).
  • Meat from exclusively grass-finished animals had 2.5 times as much omega-3 fatty acid as meat given a finishing diet of 70% grain.
  • The omega-6 to omega-3 ratio ranged from 1.2 in grass-finished meat to 2.2 in 70% grain-finished meat.
  • Meat from grass-finished animals had slightly more CLA than meat from grain-finished animals.

This is the first study that I have seen showing that use of hormones in cattle decreases the amount of omega-6 fat in the meat from these animals. It also contradicted the usual belief that grain-finishing increases tenderness, indicating that if we allow grass-finished animals to accumulate back fat to levels equal to grain-finished animals, meat from these animals will have tenderness equal to meat from grain-finished animals.

Rule et al compared muscle fatty acid profiles of bison (range vs. feedlot), beef (range vs. feedlot), elk (wild), and chicken. They found:

  • Generally, range fed beef and bison have higher total amounts of PUFA and a higher PUFA/SFA ratio than feedlot finished, due to higher contents of omega-3 fatty acids.
  • Range-fed beef and bison had omega-3 fatty acid levels similar to wild elk and 3 to 4 times that found in feedlot-finished meat.
  • Feedlot feeding increased total fat content (g/100g) by 50 to 100%.
  • Range-finished beef and bison had total fat contents (g/100g) similar to wild elk and skinless chicken breast.

This graph from depicts the findings of Rule et al:  

Rule et al found the following ratios of omega-6 to omega-3 fatty acids:

  • Range-fed bison, 2.09
  • Feedlot bison, 7.22
  • Range-fed beef, 2.13
  • Feedlot beef, 6.28
  • Elk, 3.14
  • Chicken breast, 18.5

Rule et al concluded:

“Range-fed bison and range-fed beef cows would provide consumers with very lean meat that is comparable to meat from free-ranging elk with respect to fatty acid profiles currently regarded as the most healthful. The feeding regimen for bison production affects the leanness and fatty acid profile of the meat. Range bison production should be emphasized to obtain the leanest bison meat with the lowest cholesterol concentration possible.”

Grass provides greater amounts of selenium than grain, so grass-finished animals have higher levels of these minerals than grains. Marchello and Driskell [Great Plains Research 11 (Spring 2001): 65-82] found that grassfed bison have as much as four times more selenium (an essential trace mineral) than grainfed bison. Eating just three ounces of grassfed bison, for example, supplies more than 100 mcg. of selenium, which is several times the daily minimum requirement.  Selenium plays an important role in thyroid function, protects the body from mercury, and appears to have anticancer and cardioprotective effects.

Obviously, grass-finished meat (lean cut) gives you substantially greater nutritional value than grain-finished meat, particularly for vitamin E complex, B-carotene and mixed carotenoids, riboflavin, niacin, selenium, and omega-3 fats, along with a lower levels of total, saturated, and monounsaturated fat.  

The Omega Issue

A high dietary ratio of omega-6 to omega-3 fatty acids may have adverse effects.  In August 2010, Massiera et al reported results of a study in which they fed mice a diet containing 35% of energy as fat, and 28 times as much omega-6 as omega-3 fat, over successive generations—a situation similar to the typical Western diet.  The results reported in the abstract:

“Offspring showed, over four generations, a gradual enhancement in fat mass due to combined hyperplasia and hypertrophy with no change in food intake. Transgenerational alterations in adipokine levels were accompanied by hyperinsulinemia. Gene expression analyses of the stromal vascular fraction of adipose tissue, over generations, revealed discrete and steady changes in certain important players, such as CSF3 and Nocturnin. Thus, under conditions of genome stability and with no change in the regimen over four generations, we show that a Western-like fat diet induces a gradual fat mass enhancement, in accordance with the increasing prevalence of obesity observed in humans.”

Stephan Guyenet discussed this research in detail here.  Thus, it appears that a high n-6:n-3 ratio may promote obesity and adversely affect gene expression across multiple generations. As Stephan demonstrates in a series of articles on the topic of fats, a high intake of omega-6 oils also appears to promote cardiovascular disease, cancer, osteoporosis, liver disease, and several other diseases of civilization.  However, we should note that in the three studies I have quoted, the ratio of omega-6 to omega-3 in grain-finished beef or bison did not exceed 7.22, a far cry from the 28 to 1 ratio used in this study. In contrast, chicken breast has a ratio of 18.5.

Furthermore, the absolute amount of omega-6 fat in any of these foods is relatively small.  Using the USDA database, we find the following (food, weight, omega-6 mg):

  • Grain-finished beef chuck with ¼” fat, 100 g, 218 mg
  • Grain-finished beef chuck with ¼” fat, 1 pound, 1 g 
  • Game meat, bison, chuck, shoulder clod, separable lean only, raw, 100 g, 114 mg

In cattle and bison, both ruminants, it appears that the microbes in their guts consume or transform most of the omega-6 in feed grains, such that, as noted in the studies cited above, the absolute amount of omega-6 in their tissues remains constant regardless of finishing method.  Their tissues develop a high n-6:n-3 ratio by route of feed grains lacking omega-3s that they would get from grass or other foraged foods. 

Now compare USDA data for lamb and pork:

  • Grain-finished lamb, domestic, composite of trimmed retail cuts, separable lean and fat, trimmed to 1/8" fat, choice, raw, 100 g, 1 g  (0.330 g n-3)  
  • Grain-finished lamb, domestic, composite of trimmed retail cuts, separable lean and fat, trimmed to 1/8" fat, choice, raw, 1 pound, 5g (1.5 g n-3) 
  • Pork, fresh, composite of trimmed retail cuts (leg, loin, shoulder, and spareribs), separable lean and fat, raw, 100 g, 1.3 g (0.09 g n-3)
  •  Pork, fresh, composite of trimmed retail cuts (leg, loin, shoulder, and spareribs), separable lean and fat, raw, 1 pound,  6.0 g (0.4 g n-3)

Lamb and pork have about 5 to 6 times as much omega-6 as beef and bison.  Lamb has in its favor a relatively high content of omega-3, with a n-6:n-3 ratio of 3:1.  This makes it a really good choice for a practically paleo diet.  Pork has a less favorable ratio (15:1), so I would suggest keeping pork to a smaller fraction of the total diet.

Now take a look at the omega-6 levels in the following (food, serving,  omega-6):

  • Chicken thigh with skin, one pound, 13.6 g
  • Chicken thigh without skin, one pound, 9.5 g
  • Chicken breast with skin, one pound,  6.4 g
  • Chicken breast without skin, one pound,  2.7 g
  • Walnuts, 1 ounce (14 halves), 10.8 g
  • Walnuts, 100 g, 38 g
  • Safflower oil, one teaspoon, 3 g
  • Safflower oil, one tablespoon, 10 g. 

Some comparisons:
  • Chicken thigh with skin thus has a little more than twice as much omega-6 as lean grain-finished pork, and nearly 14 times as much as fatty grain-finished beef chuck.  
  •  Chicken thigh without skin supplies about 50% more omega-6 than grain-finished pork, and 9.5 times as much as fatty grain-finished beef.   
  • Chicken breast with skin provides about half as much omega-6 as pork and 6.4 times as much as the fatty chuck.   
  • Chicken breast without skin has nearly 3 (2.7) times as much omega-6 as fatty beef on a weight basis.  
  •  Just one ounce of walnuts provides six times more omega-6 than a whole pound of pork, and 10.8 times more than a whole pound of fatty grain-fed beef.   
  • Just one teaspoon of safflower oil provides nearly twice as much omega-6 as a whole pound of pork shoulder, and 3 times as much as a whole pound of fatty grain-fed beef.

So, if you want to avoid excess omega-6, you should focus on eliminating chicken skins; limiting dark meat poultry, pork and chicken breasts; limiting nuts high in polyunsaturates (most are); and most importantly eliminating all vegetable oils except olive, palm, avocado, and coconut.  If eating grain-finished meats as staples, focus on using beef, bison, and lamb.  Use less of leaner cuts of pork and poultry.

The balancing act

These data make it very clear that the best way to reduce your intake of excessive omega-6 oils lies in restricting intake of chicken and eliminating most tree nuts and vegetable oils from your diet.  If you do this, you can easily attain a healthy total diet ratio of omega-6 to omega-3 even if you eat only grain-finished beef, lamb, pork, and bison, by including some fatty fish like salmon, sardines, or sea bass in your diet. 

As we saw above, a pound of fatty beef has 1.0 g of omega-6.  Assuming that you limit all other significant sources of omega-6 in your diet, if you consume 6 pounds of beef in a week, you will get 6 g of omega-6.  To get an ideal 1:1 ratio of omega-6: omega-3 in your overall diet, you will need to eat something that will provide 5 g of omega-3s with almost no omega-6, such as salmon or sardines.  Take a look at the USDA figures for the amounts of omega-3s in these canned fish:

  • Salmon, pink, canned, solids with bone and liquid, 100 g, 1.7 g
  • Sardine, Pacific, canned in tomato sauce, drained solids with bone, 100 g, 1.7 g

Thus, 350 g (12 ounces) of either salmon or sardines in the week will give you enough omega-3 to balance out 6 pounds of beef.  So I could eat a pound of beef each day 6 days each week, then have three-quarters of a pound of salmon on the 7th day, to get the desired ratio.  Alternatively, I could eat my pound of beef daily with a few sardines to achieve the same result.

Now let’s say that you make a mistake that I made, and eat 100 g of walnuts daily.  This would provide you with 266 g of omega-6 each week.  You can see that you would have to eat a ridiculous amount of salmon or sardines – namely,  15 kg/34 lbs – each week to achieve a 1:1 ratio of omega-3 to the omega-6 in those walnuts.

You can also see that you could easily consume excessive amounts of omega-6 eating a diet based on “lean” grain-fed poultry rather than red meat.  A primal dieter gets the best results by basing the diet on meat of ruminants and hindgut fermenters, not poultry.

Eat fish, not fish oils

Some may wonder about using fish oils to achieve the balance of omegas.  I don’t recommend the isolated fish oils, because oils packed removed from fish often go rancid, and research suggests that they may not have the benefits of eating fish, and may increase mortality. In contrast to fish oils, whole fish supply a number of nutrients other than omega-3 fats that may promote health, including vitamin D, magnesium, and selenium.


  • Meat from grass-finished cattle, bison, or other ruminants provides higher amounts of several important vitamins, minerals, CLA, and omega-3 fatty acids than meat from grain-finished animals. 
  • Meat from cattle treated with hormones has less omega-6 than meat from cattle not treated with hormones.
  • Feeding ruminants (cattle, bison, lamb, etc.) or hindgut fermenters (e.g. pigs) grain instead of grass results in significantly lower levels of omega-3 fats, but has very little effect on the absolute amount of omega-6 in the meat.
  • Meat from ruminants finished on grain concentrate has low levels of omega-6 compared to meat from grain-fed poultry, most tree nuts, or nut or seed oils.
  • You can easily achieve a desirable omega-6:omega-3 fat ratio while eating large amounts of meat from grain-finished ruminants or hindgut fermenters by consuming reasonable amounts of fatty fish like salmon, sardines, and mackerel.
  • The main sources of omega-6 oils in most diets include meat from grain-finished poultry, tree nuts, oil seeds, and nut or seed oils.
  • If you include significant servings of any of the items listed in that previous sentence, you will have great difficulty achieving a desirable ratio of omega-6 to omega-3 oils because you will have to consume unrealistic amounts of fish or fish oils.
  • Regular intake of fatty fish can easily counterbalance the omega-6 found in grain-finished beef, pork, bison, or lamb, so long as you minimize intake of chicken, temperate tree nuts, oil seeds, and nut or seed oils.

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Wednesday, January 19, 2011

Study: Strength Training Lowers Blood Pressure Equal to Medication or Aerobics

A study published in the Oct 2010 issue of the Journal of Strength & Conditioning Research by Collier et al [1] reports that resistance training (3 sets, 10 reps; upper and lower body at 65% 1 repetition maximum) produces greater increases in limb blood flow and a greater reduction of blood pressure  at (40 minutes postexercise) when compared to aerobic exercise.

According to Kathleen Blanchard writing for,  the study found a 20 percent reduction in blood pressure at 45 minutes after a resistance training session.  This reduction persisted for 24 hours and is equal to or greater than what can occur after use of blood pressure medication, but without side effects.

1. Collier, SR, Diggle, MD, Heffernan, KS, Kelly, EE, Tobin, MM, and Fernhall, B.  Changes in Arterial Distensibility and Flow-Mediated Dilation After Acute Resistance vs. Aerobic Exercise. Journal of Strength & Conditioning Research: October 2010 - Volume 24 - Issue 10 - pp 2846-2852

Thursday, January 13, 2011

The Practically Primal Guide to Conventional Beef, Part 2: Antibiotics, Chemicals, and Pesticides

As an advocate of grass-fed animal products, I have been critical of practices like use of antibiotics in livestock, but not always with adequate information.  Like other people critical of confined animal feeding operations (CAFOs), I started this investigation with the idea that we should raise animals in a manner as close to wild as possible, which would preclude the use of antibiotics.  

People critical of conventional animal products often claim or imply that these products carry harmful residues of antibiotics and other chemicals, particularly pesticides.  I realized that I had accepted these charges without doing investigation myself.   I wanted to find out if this is the case, both to have my facts straight when talking about any possible advantages of grass-fed meats, and to know if I should advise people to avoid these products at all costs, including not eating meat unless you can afford grass-fed animal products. 

Do Livestock Get Overloads of Antibiotics?

Based on data supplied by the FDA, some people have gotten quite upset to find that, by crude weight, 80% of all antibiotics used in the U.S. get used in livestock production, the other 20% getting used in human medicine.  Opponents of antibiotic use claim that this “overuse” of antibiotics in animals constitutes the main cause of antibiotic resistance in bacteria. 

Although I am not a fan of antibiotic use, I find it inappropriate and illogical to evaluate the use of antibiotics on the basis of total tonnage given to either all livestock or all humans in the U.S.  Medical personnel give doses of antibiotics according to weight, not according to head.  In humans, children get smaller doses than adults based on weight.  Pigs, averaging 230 pounds each, would get larger doses than the average 150 pound human, and cattle, averaging 1300 pounds, require even larger doses. 

According to USDA data , in 2008  U.S. livestock included:

  • 96, 035, 000 cattle and calves with a live weight of 41 billion pounds.  
  • 66, 708, 000 hogs and pigs with a live weight of about 30 billion pounds.   
  • 5,950,000 lambs and sheep, weighing 440, 286, 000 pounds.   
  • 9, 000, 000 dairy cattle, which would have an average live weight of about 4 billion pounds.   
  • 450 million chickens at an average weight of 5 pounds gives 22.5 billion pounds of chickens.   
  • 6 billion pounds of turkey   

These numbers have varied only marginally for 10 years spanning 2000-2009.

Using an average weight for humans of 100 pounds (including children), and a U.S. population of 300 million, we can calculate that the total weight of humans in the U.S. comes to about 30 billion pounds.  From the above data, we can see that the weight of livestock in the U.S. is in the range of about 104 billion pounds, about 3.5 times the weight of humans in the U.S..  Adding miscellaneous food animals (bison, ducks, and others) not counted in the USDA data would bring the weight of animals even higher.

Since antibiotics are dosed by body weight, if we used antibiotics in animals at the same rate as in humans, we would expect that we would annually use three to four times as much antibiotics (by gross weight) in treating animals as in treating humans.  The Center for A Livable Future  reports that in 2009 we used about 29 million pounds of antibiotics for food animals, and about 7 million pounds for humans, or just about 4 times as much in food animals in humans.  Calculated by weight, the use of antibiotics in food animals does not vary much from the use in humans; so if we are overusing antibiotics in animals, we’re also overusing them in humans (on a per weight basis).

We don’t administer low doses of antibiotics to children to increase their rate of growth, yet on a weight basis we seem to use nearly as much antibiotics in people as in livestock.  Since it appears that antibiotics get used in food animals at about the same rate per pound that we use them in humans, this should put to rest the Center For A Liveable Future’s speculation that livestock producers “most likely administered them [antibiotics] in continuous low-dosages through feed or water to increase the speed at which their animals grew.”

Antibiotic Resistant Bacteria

I don’t know why veterinarians apparently get most of the heat for supposedly overusing antibiotics in livestock.  As a Chinese medicine provider, I routinely treat people who have received prescriptions for antibiotics from conventional medical doctors for acute upper respiratory conditions without anyone performing cultures to determine whether the infection is bacterial or viral.  The vast majority of such conditions are viral, and viruses are not susceptible to antibiotics. 

I also have many people tell me that their physician prescribed antibiotics for their chronic sinusitis, but Mayo Clinic research suggests that most chronic sinus infections are fungal.  Antibiotics don’t affect fungi, in fact they enhance fungal growth by killing off harmless flora that would otherwise keep fungal infections at bay.  Thus, I would guess that widespread, essentially indiscriminate use of antibiotics in humans is the most likely cause of antibiotic resistant strains of bacteria that commonly infect humans. 

Then, how about people flushing antibiotics and other drugs down their toilets or sinks?  Whether done intentionally (disposal) or by urination and defecation after using the drugs, it contributes to antibiotics and other drugs occurring in tap water.  This direct deposit of drugs into municipal water supplies can in part account for the multiple antibiotic resistant (MAR) bacteria found in drinking water

Further, it seems to me that anyone who has the idea that we could prevent bacteria from developing antibiotic resistance has failed to understand the basic biological principle of evolution by natural selection.  If you understand this principle, you will see that any use of antibiotics at all contributes to the development of antibiotic resistant strains, and that it is only a matter of little time before fast-reproducing microbes develop resistance to all of our antibiotics. 

Here’s the view based in understanding of the principle of natural selection:  Antibiotics present a environmental stress to bacteria.  In any bacteria population, there will exist a variation in susceptibility to any one antibiotic.  Some will have little or no resistance, and some will have complete resistance.  Whenever we use an antibiotic, we will kill off the bacteria that have insufficient resistance, and those with resistance will remain to reproduce.  This will happen whether we use the antibiotics on a herd of cattle or a human population, even on one individual. 

In short, the principle of natural selection predicts the eventual failure of antibiotics.  As an alternative, I could suggest that we curtail our use of antibiotics, and instead put attention on fortifying host resistance by hygiene, proper diet (for vitamin A and numerous other nutrients) and sun exposure (for vitamin D), use herbs that contain multiple natural antimicrobials for routine antimicrobial purposes, and leave the high dose antibiotics for a last resort.

However, taking another perspective,  I can’t control the actions of other people, and we will adjust to super microbes as surely as we have adjusted to conventional microbes.  If we exhaust the usefulness of antibiotics, this may indeed serve us better in the long run by forcing us to look for better ways to control infectious disease, like increasing host resistance in the manner I have suggested. 

By the way, although we have a great outcry about the supposed increase of antibiotic resistant microbes in developed nations, I haven’t seen any dramatic increase in infectious disease in these nations.  Infectious disease still wreaks its greatest toll in poorly nourished developing nations. 

Antibiotic and Chemical Residues in Meats and Dairy?

The Food Safety Inspection Service of the USDA performs random tests of animal products for residues of antibiotics and fifteen other chemicals or classes of chemicals, and publishes the findings annually.  Below I have copied the page from the 2008 edition of the FSIS National Residue Program Data (aka “Red Book” ) .

Click for larger version.

According to this data, of 4146 samples tested for antibiotic residues, 276, or about 7%, had antibiotic residues that did not exceed residue limits (i.e. non-violative), and only 2 samples, or 0.05%, had violative residues.  Since the USDA impounds products that violate the residue limits, not allowing their sale, this suggests that 93% of animal products on the market have NO antibiotic residues, and the other 7% have residues that have no health effects because they are not large enough. 

If you survey the rest of the list, the FSIS found violations of residue limits for only 5 other chemicals or classes of chemicals:  arsenic, avermectins,  carbadox, chlorinated hydrocarbons or organophosphates, or sulfonomides.  In each case, the violations occurred in much less than 1% of samples. 

Based on production class (i.e. type of animal) the FSIS found violations occurred in beef cows, boars/stags, bob veal, bulls, goats, heavy calves, heifers, market hogs, non-formula fed veal, roaster pigs, and sows, with the highest numbers of violations occurring in heavy calves—2 violations out of 456 samples, or 0.44 percent.  The following graph depicts the number of samples of each production class (in the hundreds, up to nearly 1500 samples in some classes) along with the percent violations (red dots, all less than half of a percent) in each class :

Click for larger version.

The USDA FSIS page "Beef: Farm to Table" explains the regulation of antibiotic use in livestock:

“Antibiotics may be given to prevent or treat disease in cattle. A "withdrawal" period is required from the time antibiotics are administered until it is legal to slaughter the animal. This is so residues can exit the animal's system. FSIS randomly samples cattle at slaughter and tests for residues. Data from this Monitoring Plan have shown a very low percentage of residue violations. Not all antibiotics are approved for use in all classes of cattle. However, if there is a demonstrated therapeutic need, a veterinarian may prescribe an antibiotic that is approved in other classes for an animal in a non-approved class. In this case, no detectable residues of this drug may be present in the edible tissues of the animal at slaughter.”

This Purdue University video describes what happens when the FSIS discovers that a producer has product that contains violative residues:

In short, producers stand to lose their businesses if they produce animals with antibiotic or chemical residues exceeding USDA limits.

I know some may not trust the USDA, considering it in league with the producers to cover-up their misdemeanors.  I myself fall into that class.  You might want to consider the report of Schnell et al, entitled Pesticide Residues in Beef Tissues from Cattle Fed Fruits, Vegetables and Their By-products, from The Journal of Muscle Foods.  The abstract:

“Muscle, adipose, liver and kidney tissue samples were collected from cattle fed potato processing residue (n=20), apple pomace (n=20), pear pomace (n=10), cannery corn waste (n=20), cotton gin trash (n=20), tomato pomace plus almond hulls (n=16), dried grape solids (n=10) or dried citrus pulp (n=6) as well as from control cattle which were not fed fruits, vegetables or their byproducts (n=21). All adipose tissue samples (n=143), representative samples of the above feeds (n=24) and representative samples of muscle (n=35), liver (n=35) and kidney (n=35) tissues were assayed for acephate, benomyl, captafol, cypermethrin, folpet, azinphos-methyl, captan, chlorothalonil, ethyl parathion, and permethrin. In 2,720 tests for the aforementioned oncogenic pesticides, eight tests were positive, but no residue amount that would be considered violative was detected. The only pesticide detected was benomyl and it was detected at nonviolative levels in the adipose tissue of cattle that had been fed either apple pomace or pear pomace.”

Thus, Schnell et al found pesticide residues in only 8 of 2,720 samples, i.e. 0.29%, from cattle fed several different foods that may have pesticide residues.  This gives some indication of the low levels of residues on these particular crops (apples, pears, corn, cotton, tomato, grape, and citrus), or of the efficiency with which the liver and kidneys of bovines get rid of residues.  Note also that they tested liver samples, confirming my long held belief that liver does not store but transforms and eliminates toxins from the body.

Vazquez-Moreno et al tested for pesticide residues in adipose tissue of beef, pork, and poultry from plants located in northwestern Mexico and published the results in the Journal of Muscle Foods (5 May 2007).  According the the abstract:

“This study involved testing of adipose tissue from beef (208 samples), pork (112 samples) and poultry (39 samples) for pesticide residues, including nine different chlorinated hydrocarbons (CHC) and nine organophosphates (OP). Tissues were collected during a two-year period (1996–1997) from plants located in the Northwestern Mexico, and determinations conducted by gas chromatography under international performance criteria. While none of the pork samples contained CHC residues, 17 (1996) and 11 (1997) beef samples contained either hexacholorobenzene, heptachlor, aldrin or dieldrin. Also, poultry samples (three in one year and four in the other) contained residues of either hexachlorobenzene, heptachlor or dieldrin. None of the tissues tested contained organophosphate residues above the detection limit. CHC incidences and concentrations were lower than those reported for other Mexican and Latin American regions, but higher than reports from the U.S. Based on the Mexican or U.S. tolerances, all concentrations of CHC found were nonviolative.”

In this study, no pork samples, 13% of beef samples, and 18% of poultry samples from Mexican processing plants contained CHC, while none of any samples contained OP, and in no case was the concentration of CHC above limits. 

Compare this to cabbage:  100% of cabbage samples contain at least 49 naturally occurring pesticides.
As documented by Bruce Ames (PNAS pdf), 99.99% of the pesticide load consumed by the typical American consists of pesticides that naturally occur in plant foods, which when tested have a toxicity and carcinogenicity similar to synthetic pesticides. This slide from Ames's paper lists 49 pesticides naturally occurring in cabbage (click on image for larger version):

So if you avoid conventional meats in favor of plant foods, you don't avoid pesticides or antibiotics (plants contain natural antibiotics also), and you probably increase your pesticide and antibiotic load.  But when you eat meat, as shown by Schnell et al (above), you have put a filter between yourself and the plant sources of toxins.  Relatively speaking, it appears that fresh conventional meat presents a much lower pesticide and antibiotic load than organically grown cabbage. 

Consider also that antibiotics and  persistent pesticides are ubiquitous hazards these days, and may occur in “organic” and grass-fed animal products as well as conventional.  For example, a company producing organic chicken in the UK found residues of nitrofuran, a banned pesticide, in meat from their birds

 All in all, although a part of me would prefer to have "pure" animal products without residues of any potentially toxic chemical, the reality is nothing is "pure."  From my perspective, it seems that most conventional animal products have no antibiotic, pesticide, or chemical residues, and in the small percentage (less than 0.5%) that has residues, they occur in amounts that present no hazard to health.

Saturday, January 1, 2011

Study: Strength Training Improves Flexibility, Equal To Or Better Than Stretching

Conventional wisdom maintains that stretching improves flexibility and that strength training makes people "muscle bound"--i.e. less flexible.   I have known for years through self-experimentation that this is hogwash, and have often maintained that properly performed strength training improves flexibility on par with stretching. 

Yesterday I learned that a pilot study presented at the American College of Sports Medicine’s 57th Annual Meeting on June 4, 2010 has confirmed my observations.  The report states:

Researchers compared the two techniques’ effect on flexibility of the same muscle/joint complexes in a five-week intervention.
“The results suggest that carefully constructed, full-range resistance training regimens can improve flexibility as well as—or perhaps better than—typical static stretching regimens,” said James R. Whitehead, Ed.D., FACSM, presenting author of the study.
Twenty-five college-age volunteers were randomly assigned to groups performing either resistance training or static stretching. A 12-person control group remained inactive. All were pre-tested on hamstring extension, hip flexion and extension, and shoulder extension flexibility, as well as peak torque of quadriceps and hamstring muscles. The resistance training and stretching programs focused on the same muscle-joint complexes over similar movements and ranges. Post-tests measured flexibility and strength.

The results—which may surprise advocates of stretching to improve flexibility—showed no statistically significant advantage of stretching over resistance training. Resistance training, in fact, produced greater improvements in flexibility in some cases, while also improving strength. [Italics added]

Although this was a "preliminary" study, I have no doubt that the larger study planned will have the same outcome.  Properly performed, strength training can give you strength, flexibility, and cardiovascular fitness as well.