Tuesday, January 31, 2012

Wheat Again

The USDA has published this chart of U.S. consumption of wheat flour between 1830 and 2008.

Before 1850, U.S. consumption of wheat was lower than between 1850 and 1910.  The USDA explains:

"Wheat production was difficult in New England and in much of the South in the colonial era (1600s and 1700s), making wheat flour too expensive for regular use. High transportation costs also made long-distance transport of wheat and flour from regions better suited for wheat growing unprofitable. Therefore, colonists in these regions turned to other crops, especially corn. The wealthy were the principal consumers of wheat bread."

In the U.S., wheat flour (and thus wheat bread) consumption peaked in the late 19th century at about 220 pound per capita per annum.  That means that in the late 19th century, U.S. citizens were consuming an average of about 10 ounces of wheat flour daily.

That would provide about 950 kcalories, 37 g protein, and 200 g carbohydrate from whole wheat flour alone.   It is equivalent to consuming 12 slices of whole wheat bread daily.

About 1910 the per capita wheat flour consumption dropped below 200 pounds, and now it is about 150 pounds per annum, so we have seen a 32 percent drop in wheat flour consumption since the late 19th century.

So, during the 20th century, what replaced grain consumption?  The USDA says :

"Historically, economic development has been accompanied by the substitution of meat for grain in the diet, and this was true in the United States starting in the 1870s."

The substitution of meat for grains as a consequence of economic development represents part of what nutritionists have called the  nutrition transition ,  which Popkin characterizes here :

"Major dietary change includes a large increase in the consumption of fat and added sugar in the diet, often a marked increase in animal food products contrasted with a fall in total cereal intake and fiber."
Put another way, up until the late 19th century, the U.S. was an agrarian nation.  Agrarian nations typically derive most of their sustenance from cereal grains and this was true of the U.S. for its first 100 years, during which corn and wheat provided the majority of calories consumed by the majority of people.

So far as I can tell, rates of obesity, diabetes, and cardiovascular disease in the U.S. went up during a time when consumption of wheat and corn was well below that of the late 19th century.

According to an article by B.C. Curtis posted on the Food and Agriculture Organization website, the French consume almost twice as much wheat per capita as people of the United States.

According to World Health Organization data, the U.S. has about 2.5 times as many heart disease deaths as France.

France also has an obesity rate one-third of that of the U.S.A..

It doesn't look like consumption of bread increases the risk of heart disease or obesity in France.

We do have evidence indicating that whole grains including whole wheat protect against heart disease.

Groen (pdf) studied the effect of dietary wheat bread on serum cholesterol.  He found first that Trappist monks, Yemenite Jews, and Arab Bedouins consumed an average of 600, 500, and 750 g of bread daily, compared to an average of 150 g bread daily in a Western diet, but the bread eaters had low serum cholesterol levels and very low risk of ischemic heart disease.

The Bedouins consumed the most bread (750 g daily) and the least animal protein (5 g daily) and total fat (38 g) and had the lowest serum cholesterol.

One slice of bread weighs about 30 g, so the Trappists ate about 20 slices daily, the Yemenites about 17 slices, and the Bedoins about 25 slices daily, compared to about 5 slices in the typical Western diet.  These levels of bread intake are common among people who eat bread as a staple food.

Groen compared the effects on serum cholesterol of low-fat, low-sugar diets  in which most of the protein came from animal sources, or most of the protein came from wheat gluten.  The study suggested that a gluten-rich diet may produce a lower cholesterol level than one based on animal protein.

Groen also found that replacing bread with equal caloric amounts of sugar raised serum cholesterol.

Friday, January 20, 2012

Study: Sleep Deprivation Activates Hunger Center of Brain

A team of Swedish researchers from Uppsala University, led by Christian Benedict and Helgi Schiöth, have published a report in the Journal of Clinical Endocrinology and Metabolism indicating that acute sleep deprivation enhances the brain's response to pleasurable food.

They found that "Compared with sleep, total sleep deprivation was associated with an increased activation in the right anterior cingulate cortex in response to food images, independent of calorie content and prescan hunger ratings."

According to an article about this study by Kathleen Blanchard, RN:

"Christian Benedict and Helgi Schiöth, of the Department of Neuroscience at the University also showed that lack of sleep leads to increased hunger.

"According to Benedict, findings from their newest investigation revealed, “After a night of total sleep loss, these males showed a high level of activation in an area of the brain that is involved in a desire to eat.”

"The study participants were shown images of food during the brain scans, with and without a good night’s sleep.

"Benedict adds, 'Bearing in mind that insufficient sleep is a growing problem in modern society, our results may explain why poor sleep habits can affect people’s risk to gain weight in the long run. It may therefore be important to sleep about eight hours every night to maintain a stable and healthy body weight.' ”

Over the twentieth century, average sleep duration for U.S. citizens declined from about 9 hours daily to about 7 hours daily.   During that same time, per capita energy intake and obesity rates both increased.

McAllister et al suggest "that a myopic emphasis on" changes in food habits and activity levels as causes of weight gain has "caused the popular media, and perhaps some researchers as well, to neglect the potential contributions of other factors to the balance between energy intake and expenditure." 

"Our questioning of the big two stems from two points. First, the evidence supporting various elements of the big two as contributors to individual or population levels of obesity is often quite weak. Second, even though some elements of the big two do very likely play some role in influencing obesity levels, we believe that an unquestioned assumption of their preeminence has led to the possibly ill-advised expenditure of public effort and funds on programs aimed at reducing population levels of obesity and has also reduced the exploration of other potential causes and the alternative obesity reduction programs that might stem from their identification."

 McAllister et al point to evidence showing that sleep deprivation and nine other factors––including microorganisms, epigenetics, increasing maternal age, greater fecundity among people with higher adiposity, assortative mating, environmental endocrine disrupters, pharmaceutical medical interventions, reduction in variability of ambient temperatures, and intrauterine and intergenerational effects–– have have all played a role in promoting the obesity epidemic.

Thursday, January 5, 2012

Wheat Belly: Fat or Flat

Does a diet high in refined wheat bread make people hungry, fat, diabetic, and prone to cardiovascular disease, as claimed by some authors?

In 1979, Mickelsen et al (full text here ) wanted to see if people can eat a diet high in regular refined wheat bread and lose body fat.  Their rationale follows:

This paragraph seems to fit our times though written more than 30 years ago:

"Incorrect assumptions have taught that bread should be eliminated from weight control plans; this idea has been fostered by the recommendations and instructions of many weight-reducing plans (2).  The instructions of many fad-type diets state that 'starchy' foods such as bread and potatoes should be avoided...Measurement of food intake and caloric deposition in the carcasses of rats fed a high-fat or a natural grain diet indicated that for each 1000 cal intake the high-fat fed rats retained twice as many calories as the grain-fed animals (3)."

To find out if a diet high in wheat grain would have the same effect on humans as on rats (reduced caloric retention), Mickelsen et al recruited 16 overweight college males, all of whom wanted to lose between 4.5 and 12 kg (10 to 26 pounds).

The subjects all agreed to eat all meals in a cafeteria, avoid alcoholic beverages, and consume 12 slices of wheat bread every day (four slices at each of three meals) for eight weeks.  Mickelsen et al randomized the subjects into two groups, one of which received high fiber bread and the other received white bread (i.e. made from refined wheat).  All subjects “were instructed that to lose weight, they would have to restrict caloric intake” but they were allowed to eat as much as desired at meals and were also allowed to snack between meals as desired. 

The two types of bread differed in several respects.  The high fiber bread supplied 50 calories and two grams of fiber per slice, while the regular bread supplied 70 calories and only one-tenth of a gram of fiber (the high fiber bread had 20 times the fiber of the regular bread).  The high fiber bread had about half as much fat and twenty-five percent less digestible carbohydrate than the regular bread. The high fiber bread had about 50 percent more iron, present in the added fiber, and was enriched with calcium because the researchers anticipated that the high fiber bread would reduce calcium absorption, although it turned out that the higher fiber intake did not reduce calcium absorption.

Thus, each day of the study period, those eating the high fiber bread ingested 600 calories and 108 g carbohydrate from wheat bread, and those eating the regular bread ingested 840 calories and 156 g carbohydrate from wheat bread. 

For comparison, Ezekiel Bread, a favorite of Ripped author Clarence Bass, supplies 11 g of digestible carbohydrate, 3 g of fiber,  4 g of protein, and 65 calories per slice (the label lists 80 calories per slice but that was derived by including the potential caloric value of the indigestible fiber, which is unavailable to us).  A loaf of Ezekiel Bread has 20 slices, so the subjects of this study ate more than half a loaf of bread every day.  Twelve slices of Ezekiel Bread supplies only about 780 calories, about half of the 1500 calorie intake that would produce weight loss in many women.

So did eating all this wheat make their bellies fatter, or flatter?

Over the eight week period, the subjects eating the regular bread lost an average of 6.25 kg (about 14 pounds; range 4.2 to 7.3 kg), while the subjects eating the high fiber bread lost an average of 8.77 kg (about 19 pounds; range 6.2 to 11.4 kg).  Thus, those eating 12 slices of white bread daily lost an average of one and three-quarters pounds of body weight each week; and those eating 12 slices of high fiber daily lost an average of two and two-fifths pounds of body weight each week.  They did not make any changes in activity level.

Of interest, the subjects succeeded in reducing their caloric intake by 25 to 38 percent while simultaneously experiencing a decrease in hunger.   At the end of the study, the subjects consuming the high fiber bread reported that they did not feel hungry at any time.  Two of the subjects eating the regular bread did feel hungry at the end of the study, one of those only before meals.

The group eating the regular bread had a decrease in serum cholesterol from 231 to 155 mg/dL,  and the group eating the high fiber bread decreased serum cholesterol from 224 to 172 mg/dL.

Follow-ups on 9 of the participants at 3 months, 6 months, and 9 months found that those four who stopped eating the bread regained the weight they had lost, while those five who continued to eat the bread (regular, higher calorie) either maintained most of their weight loss or lost even more weight.


In summary, this study found that all participants reduced their hunger, cholesterol levels, and body weight by deliberately consuming a dozen slices of bread each day, four slices at each of three meals, more than half a loaf of bread daily, regardless of whether the bread was high in fiber or made from refined white flour.   Those who abandoned this regimen gained the weight back and those who continued to eat a diet revolving around refined white bread maintained their weight loss or lost even more weight. 

Eating 12 slices of wheat bread did not
  • increase their hunger (it decreased their hunger)
  • increase body weight (it resulted in weight loss by reducing other food intake)
  • increase their blood sugar levels (they had no change in blood sugar levels)
  • raise the risk of heart disease (it decreased the levels of a major heart disease risk factor, total serum cholesterol)
All this without inducing the headaches, nausea, malaise, fatigue, and constipation that commonly affect people, particularly women, when consuming high-fat, low-carbohydrate diets.

This study using Caucasian subjects resonates with the experience of millions of Asians who eat an average of one pound of dry rice daily and maintain low body fat levels throughout their lifespan. 

Source:  Abdullah et al (full text pdf)