Revised dietary Guidelines for Americans were released on 31 Jan. 2011 with a 2 page document recommending specific foods that should be part of a healthy diet.
Preferred food choices are listed and illustrated by a platter containing balanced calories from Fruits, Vegetables, Grains and Proteins, with a side plate of Dairy. (See ChooseMy Plate.gov).
The revised Dietary Guidelines replace the previous Dietary Guidelines as illustrated by the Food Pyramids of 1992 and 1995.
The failure of the Pyramids as a healthy guideline has been critically documented previously (www.leinsterclinic.ie/reviewing our approach to the Obesity Crisis) and the revised Guidelines represent an attempt to address the shortcomings of earlier dietary recommendations. (1)
PYRAMIDS and PITFALLS:
The dismal consequences of following the traditional Pyramid recommendations, as proposed by the American Heart Association (AHA) and the United States Dept of Agriculture (USDA), are clearly evident in the American statistics for disease and disability, with 66% of adults and 33% of children being overweight or obese, and 35% having pre-diabetes.
The increasing rate of obesity amongst Irish males (24%) and females (26%), with a similar pattern amongst children, calls for an urgent review of current practice in respect of dietary nutritional policy.
National Health policies continue to reflect recommendations imbedded in the Pyramids, which, despite their minimal revisions between 1992 and 1995, repeatedly fail to acknowledge and address the fundamental causes underlying the unabated escalation of obesity, diabetes and their related consequences.
GUIDELINE IMPROVEMENTS:
The new Guidelines place emphasis on caloric restriction and smaller food portions, for which there is good supportive scientific evidence. (2)
The inclusion of sea-foods, whole grains, and fruits and vegetables, without the previously weighted requirements for dietary carbohydrates, represents a welcome and timely departure from the previous paradigm.
The reference to drinking water instead of fizzy drinks is welcome, but does not go far enough to identify the widely consumed carbonated beverages that contain unhealthy levels of high-fructose corn syrup (HFCS), which presents a hidden risk for diabetes, obesity, and several chronic disorders, and are yet overlooked as a major threat to human health. (3) (4).
GUIDELINE FAILURES:
The weakness of the Guidelines is its misplaced emphasis on “counting calories”, disregarding the fact that not all calories are equal, and its false estimate of “empty calories” with regards to saturated fats and dairy products.
As in the Pyramid Guidelines, warnings are issued about consuming saturated fats, on the grounds that they “raise cholesterol levels” and “high cholesterol is a risk factor for heart disease”. (5)
The Guidelines also perpetuate the dogma espoused by the AHA that “low fat” and “fat free” are synonymous with “heart health”, and that low fat, non-fat or skim milk should replace full fat milk.
These recommendations , not unlike those from earlier recommendations, ignore the findings of critical science, and instill in the public mind unwarranted fears about, and a conscious preference for, “low fat” or “fat free” foods, with increased likelihood of selecting high carbohydrate and poly-unsaturated alternatives, which are less nutritious than foods containing saturated fats, and potentially more harmful to health.
The combined inclusions, in the Guidelines, of saturated fats and trans fats in the dietary warnings ignores the distinctive differences between these two groups of fats, the former being health protective and the latter health destructive.
HEALTH BENEFITS OF SATURATED FATS;
The references to fats as “empty calories” is inaccurate, misleading and potentially harmful, and while this assessment is applicable to trans fats, it does not apply to saturated fats !
Medium chain saturated fatty acids (C6-C10) have a lower caloric value than longer chain fatty acids (C12-C18), are readily metabolized, and are an efficient source of energy for immediate use by the organs and muscles, and are NOT stored as fat. (6)
Medium chain fatty acids enhance thermogenesis, thereby enabling weight loss to occur. (7) They may also promote ketone production, a source of brain energy, in addition to the utilization of glucose. (8)
The restriction of carbohydrates, without restricting saturated fats, resulted in favourable responses in clinical studies to risk factors for diabetes and cardiovascular disease. ( 9 ) a benefit clearly ignored by the Guidelines.
Several critical reviews of the evidence have questioned the conventional public health recommendations to reduce saturated fat intake. (10)
The warnings in the updated Guidelines about fats and cholesterol are without foundation and represent unwarranted fears.
Stearic acid (C18) is a major saturated fat found in beef, chicken and pork, and has repeatedly been shown NOT to raise LDL-cholesterol, despite the Guidelines warnings of saturated fats raising cholesterol levels. (11)
Neither does Palmitic acid (C16), the most abundant saturated fatty acid in the diet, raise LDL-cholesterol in the presence of adequate linoleic acid. (12)
Low fat diets, as recommended in the Guidelines, reduce the potential for absorbing the essential fat-soluble vitamins D, A, K and E, with dire consequences for health.
Statements that saturated fats raise cholesterol, and are thus a risk factor for heart attacks, are misleading, and do not take account of the fact that saturated fats may raise total serum cholesterol levels because they raise HDL-cholesterol, thereby reducing the risks for cardiovascular disease.
Furthermore, reductions in saturated fat intake will adversely affect HDL subpopulations, by decreasing protective HDL2-C concentrations. (13)
Conversely, increasing the dietary intake of saturated fat improves the anti-atherogenic fractions with reductions in risk for cardiovascular disease. (14)
A greater intake of saturated fat was shown to correlate with reductions in the progression of coronary atherosclerosis in post-menopausal females. (15)
The failure of the new Guidelines to address the nutritional value of saturated fats reflects its continued anti-cholesterol / anti-fat policy which holds no advantage for serious efforts to counter the escalating trend of obesity, diabetes and cardiovascular disease.
It is abundantly clear that the low-fat message has failed to generate positive health outcomes, and according to Dr. Walter Willet of Harvard Public School, has “failed the test of time”. (16)
LOW FAT DAIRY RECOMMENDATIONS:
The repetitive warnings to avoid full fat milk and to replace these with low fat or non-fat variations and skim milk is a recipe for disaster, given the value of dietary fat for vitamin absorption.
While several past studies have implicated low fat dairy products in prostate cancer (17) (18 ) (19) (20) , a recent study showed reductions in heart attack risk for men and women, with INCREASED dietary intake of milk fats. (21)
The European Dairy Association (EDA) produced a consensus report from International experts at its Conference in Copenhagen on 25 Sept 2009, which stated conclusions that fears about saturated fat intake were unfounded. (22)
In 2002 Drs Willet and Leibell reported the lack of evidence for correlations between obesity and fat intake, and stated that “fat consumption within the range of 18%-40% of energy appears to have little, if any, effect on body fatness. (16)
OVERDOSED ON CARBOHYDRATES:
Previously, the Pyramids encouraged generous consumption of carbohydrates (55%), and presented their recommendations to schools, health clubs and public consumers, and through public health statements. Many school classrooms project these recommendations in conspicuously placed Pyramid charts
The new Guidelines are less aggressive in this respect, but their anti-fat pursuations leave the public with little choice other than to consume carbohydrate alternatives.
The high consumption of white bread, white sugar, white flour and refined carbohydrates, pastas, cookies, sweets, beers, beverages and breakfast cereals is inevitable as consumers are urged to avoid fats and select low-fat or non-fat alternatives.
Such selections are guaranteed to advance the trend of obesity and its related metabolic disorders since they are nutrient deficient, and often have to be artificially fortified to reflect respectable nutrient levels.
There is no such thing as an essential carbohydrate, while both fats and proteins contain essential nutrients.
Health policies promoted by our National Health bodies should abandon their obsession with fats, and focus on carbohydrate restrictions, with warnings to parents, scholars and the wider public that sugar is the culprit, and not fats, and that carbohydrate restriction, rather than calorie restriction, is predictive for weight loss and health gains.
Several well controlled studies confirm the health benefits of carbohydrate restricted diets, without any restriction of fats. (23)
The official recommendations by the AHA of 55% of daily energy obtained from carbohydrates is likely to advance, rather than retard, the escalating trend of obesity and diabetes.
The AHA diet of 55% carbohydrate intake was tested against a low carbohydrate diet in a randomised controlled trial (RCT) involving 53 healthy obese females, and produced a mere average weight loss of 3.9kg., compared with 8.5 kg loss in the low carbohydrate group. (Brehn 2003).
Samaha et al demonstrated similar weight losses in people on low carbohydrate rather than low fat diets. (24) Not only the health benefits, but the sustainability, of low carbohydrate diets was demonstrated by Yancey et al. (25)
In a review of the Cochrane Database the authors concluded that “low fats do not cause weight loss”, but carbohydrate restricted diets do cause weight loss. (26)
Numerous studies support these conclusions. (27) but their underlying principle has yet to be incorporated into national dietary policy.
OVERDOSED ON POLYUNSATURATED FATS (PUFAS)
The high consumption of vegetable oil derived PUFAS in the Western diet has disturbed the potential for a favourable balance of omega 6 and omega 3 fatty acids in individual diets, giving rise to unhealthy excesses of omega 6, and the attendant risks for a wide range of chronic inflammatory diseases.
A corresponding deficiency in dietary n-3 marine oils (omega 3) permits the unabated advance of these disease patterns, which are essentially inflammatory in character, and may involve several major organ systems.
The anti-fat campaign serves to encourage the public consumption of vegetable oils and PUFAS, such as margarines and popular spreads, purported to be “healthier” than butter, and unwittingly promotes dietary habits that are debilitating rather than protective.
UNDERDOSED ON HEALTHY FATS:
The misguided advice to replace saturated fats with PUFA vegetable oils was classically illustrated in a double blind clinical trial of 40 females, comparing the outcome of a soybean diet (vegetable oil) and a coconut oil diet ( saturated fat).
The group who consumed the saturated fat diet exhibited a greater reduction in waist circumference, and improved lipoprotein fractions, including a marked reduction in risk for cardiovascular disease.
Soybean makes up 68% of vegetable oils which are a primary source of dietary intake in the western world today.
The dietary imbalance of excess vegetable oils can be corrected by restricting the intake of processed foods, and increasing the intake of oily fish, or supplementing with n-3 marine oils (EPA/DHA) , to achieve a 4: 1 ratio or less.
High ratios have consistently been shown to correlate with chronic inflammatory disorders, which include obesity, diabetes and heart disease. (28)
A low ratio is desirable, and possible, by consuming at least 1000 mg of EPA daily, of a science based reputable product, and restricting the intake of processed foods which are characteristically high in vegetable oils and omega 6 PUFAS.
The new Guidelines fail to make these vital distinctions and do not issue appropriate warnings or offer practical recommendations.
Dr. Neville Wilson. The Leinster Clinic. Maynooth. Co. Kildare.
July, 2011.
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