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The 2010 Dietary Guidelines: Are they really about our health?

This post includes my testimony to the Dietary Guidelines Advisory Committee (DGAC), established by the U. S. Department of Agriculture (USDA) and U. S. Department of Health and Human Services (HHS) to update the previous (2005) Guidelines.

The 2010 Guidelines make four broad recommendations:

Consume fewer calories and engage in more physical activity.

Switch to a diet that is primarily plant-based (vegetables, beans, peas, fruits, whole grains, nuts, and seeds), along with seafood and fat free and low-fat dairy, and only moderate amounts of lean meats, poultry and eggs.

Avoid or greatly reduce consumption of foods containing added sugars and solid fats because these dietary components contribute excess calories and few, if any, nutrients. Reduce sodium and refined grain intake.  Reduce saturated fat intake to no more than 7% of calories and cholesterol to 200 mg per day.

Get regular exercise: for adults, 2.5 hours per week of activity at the brisk walking level, or 75 minutes at the jogging or swimming level; for kids through teens, an hour a day of some mix of these activities.

The 2010 USDA Dietary Guidelines continue the same basic recommendations that have been touted for the last 30 years.  They state at the outset that the majority of the American public is overweight or obese and yet undernourished in several nutrients.  They also state that most people are not following the previous guidelines.  I fully agree with the statement that “good health and optimal functionality across the life span are achievable goals but require a lifestyle approach including a total diet that is energy balanced and nutrient dense.”  But I differ on how to achieve these goals. My arguments are backed up by over 100 years of research that looks beyond observational studies and into the physiological mechanisms explaining our collective malnutrition, excess weight and poor health. Since Dietary Guidelines have been in place Americans have gotten appreciably fatter and more diabetic, and cardiovascular disease (CVD) is still the number one cause of death.

The Dietary Guidelines are based on several false premises: The first is that body weight is only a matter of calorie balance. The calorie is a physical measure of heat determined in a laboratory and has little to do with how the food will act in the body.  Energy partitioning is tightly regulated by hormones and genetics. Instead of a defect in calorie balance, excess weight may well be a defect in the regulation of fat metabolism; a disorder of fat accumulation, not necessarily of overeating. Insulin, an anabolic hormone, regulates the flow of energy in the body. The chronic elevation of insulin brought on by a high carbohydrate diet is the major contributor to weight gain, but there is no mention anywhere in the guidelines of blood sugar or insulin. Cells become resistant to insulin signals, the pancreas increases its insulin secretion to higher than normal levels and eventually muscle and other tissue cells become insulin resistant, but adipocytes remain inordinately sensitive to it. High glucose and insulin in the blood also cause triglycerides to remain locked inside the adipocytes. The body perceives this situation as starvation at the cellular level, hunger ensues, and more carbohydrates are eaten.1 Insulin and glucose levels are seldom low enough for fatty acids to be released for fuel when a high carbohydrate diet is eaten, as is recommended by the Dietary Guidelines. Low carbohydrate diets for weight loss and maintenance are only briefly mentioned in the Guidelines, yet many recent studies have shown their efficacy.2,3

The second false idea is that we should fear saturated fat. The 2010 Guidelines are recommending that we reduce our saturated fat intake even further, from 10% to less than 7% of total calories.  Saturated fat intake is not a predictor of CVD,4 nor is it associated with overweight by itself.  Foods high in saturated fat are nutrient dense (vitamin A in butter, vitamin D in lard, omega-3 fatty acids in grass fed beef) and are what our ancestors had been eating for thousands of years, before CVD became prevalent.  All the deleterious effects of saturated fat have been studied in the presence of high carbohydrate.  If carbohydrate intake is low the effects of saturated fat disappear.  Replacing saturated fat in the diet with carbohydrate worsens lipid profiles.5 Replacing it with polyunsaturated fats, predominantly the omega-6 fatty acids in vegetable oils, appears to ameliorate CVD, but most of the studies were confounded by changing too many other lifestyle factors at the same time.5 It is unconscionable that the DGAC lumps solid fats with sugar as substances to be avoided.  Trans fats have definitely been shown to be associated with CVD but are vastly different than natural saturated fats.  And to say that saturated fat is related to diabetes shows a woeful lack to understanding of basic biochemistry and metabolism.  It is particularly heinous to recommend low saturated fat diets for growing children.

Third, cholesterol levels do not predict heart disease.  As many people with lower than normal levels have heart attacks as people with higher levels.  Cholesterol is a very important substance in the body, necessary for building the nervous system, cell walls, hormones, vitamin D, etc.  There is no evidence that dietary cholesterol affects body levels, since the vast majority of cholesterol is synthesized in the body.  High LDL cholesterol can be a symptom of inflammation, which is related to CVD. But the remedy isn’t to lower cholesterol but to find and remove the cause of the inflammation (refined carbohydrates).  It borders on criminality to suggest that we should restrict dietary cholesterol in the diets of children who are growing and developing their nervous systems.  We will be rearing a generation of people with suboptimal intellectual as well as physical development.

Fourth, a plant-based diet is not a nutrient dense diet!  Human cells don’t differentiate between glucose molecules from whole grain bread or a candy bar. Fruits and vegetables are beneficial since they pack a lot of nutrients into fewer carbohydrates.  But whole grains are way over-emphasized, especially when whole grain foods are defined as having 51% whole grain, and whole grains contain phytates that block the absorption of minerals. There is no preformed vitamin A in plant foods, and the carotenes need fat to be absorbed and are very inefficiently converted to vitamin A in the body.  Vitamin D needs to come from animal food and, by the way, how can Vitamins A or D be absorbed from skim milk!  And there is no B12 in plant foods.  The most nutrient dense foods come from animals that have concentrated the difficult to extract nutrients from plants like grass into forms that humans can readily use. We are omnivores!  And we need the fats and proteins in animal foods for optimum functioning.

In summary, the government, nutrition and medical authorities need to stop pandering to the enormous agribusiness, food and pharmaceutical companies that fund their research.  What Americans need to eat is real food, nutrient dense animal foods like eggs, whole milk, fish, grass-fed meats with their full complement of omega-3 fatty acids and better lipid profiles, locally grown fruits and vegetables, and small quantities of properly prepared grain and legume dishes.  Only then will we be truly healthy.  Recommending partial foods like low-fat milk, egg whites, and ‘enriched or fortified’ refined grain products just perpetuates poor health. But unfortunately for the aforementioned stakeholders, there is no profit in healthy people, only in keeping us sick so that we will spend our dollars on doctor visits and lifelong drugs for chronic diseases.  Lets have a new paradigm and tell the American people not what industry wants them to hear but what they need to hear in order to take charge of their own health.  The dietary guidelines should be an ideal to strive for and not a compromise for politics and expediency.

References

1Taubes, Gary.  2007.  Good Calories Bad Calories. Challenging the Conventional Wisdom on Diet, Weight Control, and Disease. Alfred A. Knopf, New York.  601 pp.

2Gardner CD et al. 2007. Comparison of the Atkins, Zone, Ornish and LEARN diets for change in weight and related risk factors among overweight premenopausal women. JAMA 297: 969-977.

3Shai I et al. 2008. Weight loss with a low carbohydrate, Mediterranean, or low-fat diet. NEJM 359: 229-241.

4Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. 2010. Saturated fat, carbohydrate, and cardiovascular disease. AJCN 91: 502-509.

5Hu FB, Manson JE, Willett WC. 2001. Types of dietary fat and risk of coronary heart disease: a critical review.  J AM Coll Nutr 20:5-19.

{ 1 } Comments

  1. Vanessa | July 14, 2010 at 9:49 pm | Permalink

    Very true! Why do they insist on recommended a diet that consistently doesn’t work and can’t be followed? And their remedy for people not following the current recommendations is to lower the saturated fat and salt levels lower? I mean how is that suppose to help? Maybe instead they should question why people can’t deprive themselves of these nutrients? Maybe its because they are beneficial?

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