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. 

Notes: 

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

22 comments:

Greg said...

very interesting post, thank you!
Others observed that my skin was more orange after I started consuming sweet potatoes (always mashed with fat). Do you think there could be a potential down-side to beta-carotene in that it could displace storage of other fat soluble vitamins? Do you think carotenes hold an advantage (in terms of sun protection, and overall) over other options such as vitamin E?

I would be interested in hearing more on your take on skin damage/cancer. Dr. Holick states in his books that there is not any evidence to indicate that sun exposure without burning causes skin cancer.

I assume that skin cancer, like most other diseases of civilization were mostly due to dietary changes. However, it would take more evidence to convince me that cartenoids make up the difference,

Lets use the !Kung as an example. AFAICT their diet is not cartenoid rich, unless some of their tubers and roots are carotene rich like sweet potatoes. They had a brutal amount of sun exposure- even with black skin I would tend to think they would be at much greater risk for any harmful effects of the sun. Or to put it another way- if sun exposure is a large cause of skin cancer, why is the incidence higher then ever now in our culture with a very low sun exposure?

Organism as a Whole said...

Haha, great post. I think it's more due to greater blood perfusion, as Stephan said.

I noticed that my face changes into a orange color after I shower or exercise. My face also looks fuller after those activities. In fact, a lot of men and women complimented me after I exercise and said that I look good (it may due also due to my muscles looking bigger after I exercise, who knows?).

I could be wrong; humans might be attracted to others because of carotene status. Carotene status may indicate good health; resistance against infections. A benefit of this is that it may indicate good fertility for females and good genes for males.

Geoff said...

I'm super skeptical of the finding in this study.

While I could not get access to it, and as a result could not parse out the methodology of the studies that they were comparing, I suspect that for the sake of controlling variables they probably used pictures and discolored the faces using image software rather than actually taking pictures of the same person in these different states. This could lead to an unnatural look, which is potentially more unnatural in the tanned picture than in the carotene one (the sample photo in the post looks this way to me). If the study doesn't control for the naturalness of the complexion, it could easily be imagined to be a confounding variable.

I'd also imagine that it varies depending on one's skin tone, i.e. as someone with olive skin from my half greek descent, I probably gain more from getting a tan on the attractive scale than someone who is naturally paler. Micronutrients and hormones made in the skin when exposed to UV radiation are extremely important to our health, and the better we tan, the harder it is for us to make these nutrients. So while someone who is swedish may look odd with a tan as compared to their natural glow, this may not be the case for those of us with more melanin.

David Csonka said...

I have to agree with Geoff on the methodology for the experiment. The photos look like a photoshop, rather than real images demonstrating diet induced pigment changes.

Personally, I don't think the "tanned" example looks tanned at all. They look like they have a shadow over their face.

However, the carotene - melanin connection sounds intriguing. I'll have to read more about that.

Don said...

Greg,

1 I don't think carotenoids displace storage of other fat soluble nutritients.

2. I think they clearly have advantage over vitamin E, but also note that in natural foods, carotenes and E travel together...so if you eat foods supplying carotenes, you'll also get E.

3. I agree with Holick. Eating more carotenes helps by providing photoprotection, reducing the tendency of skin to burn.

4. More evidence? I only cited about 10 studies showing that carotenes reduce the tendency to sun burn and deleterious changes in the skin d/t UV radiation. Plus, carotenes ARE a dietary influence on skin cancer...lack of carotenes FROM DIET in skin probably contributes to skin cancer.

5. !Kung: several points: a) modern !Kung do not represent ancestral diets because they do not inhabit the rich ecosystems exploited by ancestral humans, b) they eat greens and fruits that supply carotenoids, and most likely their roots do also, c) did you miss, the end of my article? H-Gs can get carotenoids by eating the partially digested intestinal contents--grasses--of prey animals.

6. You apparently missed my point...we have plenty of evidence that sun exposure can cause cancer IF the skin has too much n-6, too little carotenoids, and is allowed to burn. Our ancestors apparently ate little n-6, lots of carotenoids, and this helped protect them from sun burn, thus protected them from skin cancer. !Kung also have dark skin, lots of melanin, that protects the skin from UV damage. In people with reduced melanin, e.g. Caucasians, other photoprotective pigmenets such as carotenoids likely play an even greater role. Its all a package.

Don said...

Organism as a whole,

We have good evidence from animal studies that carotenoids affect fertility, i.e. high carotenoid concentrations may improve fertility.

http://www.ncbi.nlm.nih.gov/pubmed/7050193
http://www.ncbi.nlm.nih.gov/pubmed/9270133

Since carotenoids appear to improve or be associated with fertility in many other species AND affect external coloration, the coloration serves as a sign of fertility, thus individuals with external signs of high carotenoid concentrations become "preferred" members of the species. I see no reason why this would apply less to humans than to other species. I actually think that to deny it would be tantamount to drawing a line between humans and other species, suggesting that somehow, humans escape the general laws of biology.

Don said...

Geoff,

Stephen et al found that people preferred a carotenoid tint to skin of Africans as well as Caucasians. The effects of carotenoids and melanin are NOT mutually exclusive although the way Stephen et al discussed it, it may seem they are saying so. In my experience, my high carotenoid intake and skin content means that my tan has a brighter, yellower tint than if I did not have the carotenoids in my skin. Before I got into eating a lot of carotenoid rich foods, I was much more prone to sun burn living in Ohio (higher latitude) than I am now living in Arizona. The sun is much more intense here, but even though I go out in mid-day sun here in AZ, I never get burned the way I did in Ohio in my youth when eating a more standard american diet. By the way, due to my ancestry, I also have a bit of an olive tint...which became yellowish orange after becoming an copious carotenoid consumer.

I AM NOT saying we should not get tanned, I am saying that the presence of carotenoids in the skin modifies the skin response to sun, reducing the need for melanin. Sun exposure is important, and I think carotenoid consumption is also.

Everyone,

Note that I have updated the article with more of my thoughts.

H. said...

Don, thank you for this post. It's quite an interesting subject. I appreciate your addressing eating some plants and, especially, the carotenoids.

In case this is of use to someone:

After reading this post, I read the carotenoid page at the Linus Pauling institute:

http://lpi.oregonstate.edu/infocenter/phytochemicals/carotenoids/

And, thought, again, of Peter Dobromylskyj's post at Hyperlipid, on ketosis, in which, among other things, he mentions elevated cortisol:

http://high-fat-nutrition.blogspot.com/2009/11/brief-discussion-of-ketosis.html

Here, Dr. Emily Dean's posts addressing cortisol:

http://evolutionarypsychiatry.blogspot.com/search?q=cortisol

Dr. Richard Bernstein recommends 30g CHO per day and vegetables at all three meals, or at least, two of them. In one of his talks I heard recently, he states that his diet is not ketogenic. Drs. Kwasniewski, Lutz recommend staying out of ketosis.

Dr. Blake Donaldson, in his book, "Strong Medicine", published in 1961, wrote of his work with those who had allergies. He stated that the yellow vegetables are the least problematic, and that green vegetables have irritants that can bother some.

After initial stricter phases with some patients, Drs. Donaldson, Kwasniewski, and Lutz, have many similarities in their recommendations. I have enjoyed reading of the success with their patients.

I, too, have noticed that my skin is less sensitive to the sun.

Hope my two bits here is of use to those who are new to this way of eating.

I find this way of eating calm and regenerative.

Thanks again for this post. I quite enjoyed it.

Anya said...

a real life comment : every year we go to our vacation house to mainly lay in the sun. The last couple of years sunburn got more and more problematic for me ( I was a big mayonnaise eater). I switched to paleo eating two years ago and the sunburn was MUCH better. Last year I refused to put on any sunscreen as I do want to put anything on my skin any more I would not eat. So I prepared myself and started to drink 3 tablespoons organic red palm oil 1 month before leaving on vacation: I have never been so sunburn proof and tanned in my life...

Don said...

Anya,

Thanks for your example of exactly what I was pointing at. Red palm oil has more than 10 times the carotenoid content of carrots on a weight basis, plus it is also one of the richest natural sources of vitamin E.

Greg said...

Don, my critique was partly based on what was probably just a little bit of hasty writing in the original publishing of the article which seemed to make cartenoids appear as *the* most important factor. You have definitely shown that it is protective of the skin.

How do we know that eating gut contents of ruminants provide a lot of cartenoids? Part of this doubt comes from you showing that cattle themselves do not have high cartenoid levels. I can't find good sources on information for this issue, though. Even if gut contents are high in cartenoids, there is a lot more to the animal than the gut- that would greatly dilute those cartenoids.

Greg said...

The "Eat Stop Eat" link does now work.

One more question: are there other roles for cartenoids in the body, or does it apply itself as an anti-oxidant elsewhere?

Organism as a Whole said...

Don, thank you for showing me those studies.

Anya said...

Don,

I was also surprised at the Co-Q10 content.

Here is nutritional breakdown :
Red Palm (per 100g):
Calories 900. (Joules 3762)
100g Fat, oil.
Saturated Fat: 50,2%
of which MCT 0,2%, LCT 50% (palmitic 44,3%, others 5,7%).
MUFA omega-9: 39%.
PUFA 10,8% (omega-6: 10,5%, omega-3: 0,3%)
7 different vitamine A & E 105mg (954% ADH), caroteen 20.100mcg, sterols, polyfenols, Co-Q10, lecitine.

Maybe I should consider supplementing all year round.
Although it has a very particulate taste...

Don said...

Greg,

We have some intriguing evidence from animals and humans that suggests carotenoids may play an important role in ovarian health and hence fertility. This links to some:

http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=link&linkname=pubmed_pubmed&uid=19056531

I'm following up on some of these and probably will blog on it.

Don said...

Greg,

Grass is by nature high in carotenoids, and the carotenoid content of grass affects the carotenoid content of meat, milk, and eggs:

http://www.journalofdairyscience.org/article/S0022-0302%2849%2992144-X/abstract

Because they depend on conversion of carotenoids for vitamin A, cattle have high activity of ß-carotene 15,15'-dioxygenase, so most of the carotenoid they consume gets converted to vitamin A, so the carotenoids don't show up in meat. In addition, carotenoids are fat soluble so they show up mainly in fatty tissues (like skin) not leaner tissues, like muscle. We have some evidence that carotenes may play important roles in animal fertility, some cited on this page:

http://www.ncbi.nlm.nih.gov/pubmed?term=bovine%20ovary%20carotenes

This one in particular suggests that carotenes may have roles independent of vitamin A in bovine ovarian function:

http://www.ncbi.nlm.nih.gov/pubmed/11975747

There are others like that.

John said...

Very nice and well referenced post.

One question. There is a link in the sentence: "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".
That link points to http://www.blogger.com/. Did you intend to put a link there to another carotenoid study? Or was the link the result of an some editing mishap?


John

Don said...

John,

Thanks. I fixed the link.

Geoff said...

I'm personally still in the Kurt Harris camp in that I haven't seen any value in vegetables at all, including for their carotene content. Granted I do eat a lot of eggs, and they are free range, locally sourced orange eggs more often than not, but since going paleo I have never experienced a lack of carotene glow. I suspect that quality meats have enough carotene, even if the amount is substantially lower than the amount found in veggies, when you're not eating anti-nutrients.

I do agree with you that diet and sunburning are related, and there may be a carotene connection there, but I think it's more likely an inflammation thing. A sunburn is inflammation, and in an individual who is inflamed from their diet already, this will be much worse than in someone whose level of systemic inflammation is very low, allowing the body to appropriately respond.

Al said...

I don't recall any statements by Dr Harris that eating plant matter is undesireable; I seem to recall that he claims to eat a big salad at lunch.

My paraprased impression of Dr KGH's take-away message is: "avoid these following 4-5 major problematic food types; then your body will have a fighting chance of returning to normal healthy equilibrium".

gwarm said...

Well raw foodists had lower plasma Beta Carotene:
http://www.youtube.com/watch?v=HVi03uogzqk&feature=BFa&list=PL53AA35449C7DD652&lf=PlayList#t=24m5s http://is.gd/TSngGS 'B_carotene.pdf'

"However, in this study, total fat consumption
was similar in the diet groups, which makes fat consumption
unlikely to be the factor explaining the low plasma
-carotene concentrations in the raw food diet group.
Additionally, blood lipids are reported to be associated
with plasma -carotene levels and could thus be considered
as a covariate in the general linear model. In this
study, we did not include them in the general linear model
because we previously found no differences between
total cholesterol and LDL-cholesterol in subjects consuming
wholesome food and those on a Western diet [11] .
The same observations were reported for raw food eaters;
despite a negative trend for total and LDL cholesterol
with increasing proportions of raw food, the total:HDL
and LDL:HDL cholesterol ratios and the triglyceride levels
were not associated with the amount of raw food consumed
or the variant of raw food diet [12]"

I wonder if it's from LDL, fat intake timing w/ nutrient, or just the cooking http://is.gd/RVBa1O
"Carotenoids are transported in plasma exclusively by lipoproteins, with the distribution among lipoprotein classes determined in large part by the physical properties of the carotenoid.
...
These findings confirmed previous reports using
more nonspecific means of carotenoid analysis that the
hydrocarbon carotenoids are transported primarily in
LDL, whereas the more polar carotenoids are more evenly
distributed between LDL and HDL.
...
Heating of plant foods before ingestion improves the bioavailability of carotenoids pigments from many such foods, probably as a result of dissociation or weakening of protein-carote- noidcomplexes, or the dissolution or dispersion of crystalline carotenoid complexes. Such an effect has been clearly demonstrated for lycopene from tomato products (5). "

I have been blendtec'ing my greens with half a lemon peeled all on ice drunk with 12mm glass straw lately (with a fat source -- fat soluble vitamins absorption go up 40-80%). Wonder about toxicity upper limits.
--
And another 2011 video similar study 'tan vs carotenoid deposition' was posted using a dial (similar to photoshopping mentioned earlier):
http://nutritionfacts.org/videos/golden-glow/

gwarm said...

Mark Sisson had a post on foods to eat to protect against the sun damage

"Eat Some Lycopene

Lycopene, that famous carotenoid found in tomatoes, has been shown in a recent in vivo RCT to protect humans against sun damage. Healthy women, aged 21-47, who ate 55 g of tomato paste containing 16 mg of lycopene every day for 12 weeks experienced significant protection against acute – and potentially long term – sun damage. Remember that cooked tomatoes, and tomato products like paste and sauce, offer far more bioavailable lycopene than raw tomatoes. If you’re counting, 55 grams of tomato paste is a hair over 3 tablespoons worth."

http://healthcorrelator.blogspot.com/2010/01/vitamin-d-deficiency-seasonal.html?showComment=1316068270386#c5957828119842441587