Rebuttal to U.S. News and World Top 20 Diets
Loren Cordain1, Ph.D., Maelán Fontes Villalba2 and Pedro Carrera Bastos2
1. Department of Health and Exercise Science. Colorado State University, Fort Collins, US
2. Center for Primary Health Care Research. Faculty of Medicine, at Lund University, Malmö, Sweden
The writer of this article suggests that the Paleo Diet has only been scientifically tested in “one tiny study”. This quote is incorrect as five studies (1-7); four since 2007, have experimentally tested contemporary versions of ancestral human diets and have found them to be superior to Mediterranean diets, diabetic diets and typical western diets in regards to weight loss, cardiovascular disease risk factors and risk factors for type 2 diabetes.
The first study to experimentally test diets devoid of grains, dairy and processed foods was performed by Dr. Kerin O’Dea at the University of Melbourne and published in the Journal, Diabetes in 1984 (6). In this study Dr. O’Dea gathered together 10 middle aged Australian Aborigines who had been born in the “Outback”. They had lived their early days primarily as hunter gatherers until they had no choice but to finally settle into a rural community with access to western goods. Predictably, all ten subjects eventually became overweight and developed type 2 diabetes as they adopted western sedentary lifestyles in the community of Mowwanjum in the northern Kimberley region of Western Australia. However, inherent in their upbringing was the knowledge to live and survive in this seemingly desolate land without any of the trappings of the modern world.
Dr. O’Dea requested these 10 middle-aged subjects to revert to their former lives as hunter gatherers for a seven week period. All agreed and traveled back into the isolated land from which they originated. Their daily sustenance came only from native foods that could be foraged, hunted or gathered. Instead of white bread, corn, sugar, powdered milk and canned foods, they began to eat the traditional fresh foods of their ancestral past: kangaroos, birds, crocodiles, turtles, shellfish, yams, figs, yabbies (freshwater crayfish), freshwater bream and bush honey. At the experiment’s conclusion, the results were spectacular, but not altogether unexpected given what known about Paleo diets, even then. The average weight loss in the group was 16.5 lbs; blood cholesterol dropped by 12 % and triglycerides were reduced by a whopping 72 %. Insulin and glucose metabolism became normal, and their diabetes effectively disappeared.
The first recent study to experimentally test contemporary Paleo diets was published in 2007 (5). Dr. Lindeberg and associates placed 29 patients with type 2 diabetes and heart disease on either a Paleo diet or a Mediterranean diet based upon whole grains, low-fat dairy products, vegetables, fruits, fish, oils, and margarines. Note that the Paleo diet excludes grains, dairy products and margarines while encouraging greater consumption of meat and fish. After 12 weeks on either diet blood glucose tolerance (a risk factor for heart disease) improved in both groups, but was better in the Paleo dieters. In a 2010 follow-up publication, of this same experiment the Paleo diet was shown to be more satiating on a calorie by calorie basis than the Mediterranean diet because it caused greater changes in leptin, a hormone which regulates appetite and body weight.
In the second modern study (2008) of Paleo Diets, Dr. Osterdahl and co-workers (7) put 14 healthy subjects on a Paleo diet. After only three weeks the subjects lost weight, reduced their waist size and experienced significant reductions in blood pressure, and plasminogen activator inhibitor (a substance in blood which promotes clotting and accelerates artery clogging). Because no control group was employed in this study, some scientists would argue that the beneficial changes might not necessarily be due to the Paleo diet. However, a better controlled more recent experiments showed similar results.
In 2009, Dr. Frasetto and co-workers (1) put nine inactive subjects on a Paleo diet for just 10 days. In this experiment, the Paleo diet was exactly matched in calories with the subjects’ usual diet. Anytime people eat diets that are calorically reduced, no matter what foods are involved, they exhibit beneficial health effects. So the beauty of this experiment was that any therapeutic changes in the subjects’ health could not be credited to reductions in calories, but rather to changes in the types of food eaten. While on the Paleo diet either eight or all nine participants experienced improvements in blood pressure, arterial function, insulin, total cholesterol, LDL cholesterol and triglycerides. What is striking about this experiment is how rapidly so many markers of health improved, and that they occurred in every single patient.
In an even more convincing recent (2009) experiment, Dr. Lindeberg and colleagues (2) compared the effects of a Paleo diet to a diabetes diet generally recommended for patients with type 2 diabetes. The diabetes diet was intended to reduce total fat by increasing whole grain bread and cereals, low fat dairy products, fruits and vegetables while restricting animal foods. In contrast, the Paleo diet was lower in cereals, dairy products, potatoes, beans, and bakery foods but higher in fruits, vegetables, meat, and eggs compared to the diabetes diet. The strength of this experiment was its cross over design in which all 13 diabetes patients first ate one diet for three months and then crossed over and ate the other diet for three months. Compared to the diabetes diet, the Paleo diet resulted in improved weight loss, waist size, blood pressure, HDL cholesterol, triglycerides, blood glucose and hemoglobin A1c (a marker for long term blood glucose control). This experiment represents the most powerful example to date of the Paleo diet’s effectiveness in treating people with serious health problems.
So, now that I have summarized the experimental evidence supporting the health and weight loss benefits of Paleo Diets, I would like to directly respond to the errors in the U.S. News and World Report article.
1. “Will you lose weight? No way to tell.”
Obviously, the author of this article did not read either the study by O’Dea (6) or the more powerful three month crossover experiment by Jonsson and colleagues (9) which demonstrated the superior weight loss potential of high protein, low glycemic load Paleo diets. Similar results of high protein, low glycemic load diets have recently been reported in the largest randomized controlled trials ever undertaken in both adults and children.
A 2010 randomized trial involving 773 subjects and published in the New England Journal of Medicine (8) confirmed that high protein, low glycemic index diets were the most effective strategy to keep weight off. The same beneficial effects of high protein, low glycemic index diets were dramatically demonstrated in largest nutritional trial, The DiOGenes Study (9), ever conducted in a sample of 827 children. Children assigned to low protein, high glycemic diets became significantly fatter over the 6 month experiment, whereas those overweight and obese children assigned to the high protein, low glycemic nutritional plan lost significant weight.
2. “Does it have cardiovascular benefits? Unknown.”
This comment shows just how uninformed this writer really is. Clearly, this person hasn’t read the following papers (1 – 6), which unequivocally show the therapeutic effects of Paleo Diets upon cardiovascular risk factors. Moreover, as we have already reviewed elsewhere (10-12), high protein diets have been shown to improve dyslipidemia and insulin sensitivity, and are potential effective strategies for improving metabolic syndrome. Furthermore, mounting evidence suggests that a reduced-carbohydrate diet (which is obviously lower in sugars and cereal grains) may be superior to a western type low-fat, high-carbohydrate diet, especially in metabolic syndrome patients, because it may lead to better improvement in insulin resistance, postprandial lipemia, serum fasting triglycerides and HDL-C, total cholesterol/HDL-C ratio, LDL particle distribution, apo B/apo A-1 ratio, postprandial vascular function, and various inflammatory biomarkers (13, 14).
Finally, the evidence for recommending whole grains to reduce cardiovascular disease risk is based on epidemiological studies or intervention trials with soft end-points, while randomized controlled trials with hard end points do not seem to support it. For instance, the DART study, found a tendency towards increased cardiovascular mortality in the group advised to eat more fiber, the majority of which was derived from cereal grains (15). And of relevance, this non-significant effect became statistically significant, after adjustment for possible confounding factors, such as medication and health state (16).
“And all that fat would worry most experts.”
This statement represents a “scare tactic” unsubstantiated by the data. As I, and almost the entire nutritional community, have previously pointed out, it is not the quantity of fat which increases the risk for cardiovascular disease or cancer, or any other health problem, but rather the quality. Contemporary Paleo Diets contain high concentrations of healthful omega 3 fatty acids and monounsaturated fatty acids that actually reduce the risk for chronic disease (10-12, 17-22).
3. “Can it prevent or control diabetes? Unknown.”
Here is another example of irresponsible and biased journalism, which doesn’t let the facts speak for themselves. Obviously, the author did not read the study by O’Dea (6) or Jonsson et al. (2), which showed dramatic improvements in type 2 diabetics consuming Paleo diets.
“but most diabetes experts recommend a diet that includes whole grains and dairy products.”
If the truth be known, in a randomized controlled trial, 24 8-y-old boys were asked to take 53 g of protein as milk or meat daily (23). After only 7 days on the high milk diet, the boys became insulin resistant. This is a condition that precedes the development of type 2 diabetes. In contrast, in the meat-group, there was no increase in insulin and insulin resistance. Furthermore, in the Jonsson et al. study (2) milk and grain free diets were shown to have superior results in improving disease symptoms in type 2 diabetics.
Finally, in an interventional study including 2263 postmenopausal women, participants were assigned to a low-fat (<20% en), high whole-grain fiber (>6 servings per day), high fruit (>5 per day) and high vegetable (>5 servings per day) diet or comparison group with no advice. After 6 years of follow-up, those women with diabetes at the start of the study, and allocated to the low-fat/high whole-grain fiber, actually worsened their glucose control (24). Notwithstanding, the majority of the evidence, supports the beneficial effect of soluble fiber, found mainly in vegetables and fruits, while the evidence supporting the beneficial effects of insoluble fiber, found in whole grains, seems less evident (25-28).
4. “Are there health risks? Possibly. By shunning dairy and grains, you’re at risk of missing out on a lot of nutrients.”
Once again, this statement shows the writer’s ignorance and blatant disregard for the facts. Because contemporary ancestral diets exclude processed foods, dairy and grains, they are actually more nutrient (vitamins, minerals and phytochemicals) dense than government recommended diets such as the food pyramid. I have pointed out these facts in a paper I published in the American Journal of Clinical Nutrition in 2005 (11) along with another paper in which I analyzed the nutrient content of modern day Paleo diets (19). In addition, micronutrient analysis derived from the two studies performed by Lindeberg, et al. (5) and Jönsson et al. (2) shows that, except for calcium, a Paleolithic type diet, not only meets all of the micronutrients DRI, but in some cases exceeds that of the whole grain and dairy food diets. Regarding vitamin D, as we have already pointed out in a recent paper (12), except for fatty ocean fish, there is very little vitamin D in any commonly consumed natural (that is, not artificially fortified) food, and throughout history, almost all hominins (except for those living in the far North, such as the Inuit people) depended on the sun to satisfy their vitamin D requirements.
Moreover, most nutritionists are aware that processed foods made with refined grains, sugars and vegetable oils have low concentrations of vitamins and minerals, but not all have realized that dairy products and whole grains contain significantly lower concentrations of the 13 vitamins and minerals most lacking in the U.S. diet compared to lean meats, fish and fresh fruit and vegetables (11, 19). Interestingly, although micronutrient intake is important, intestinal absorption is even more impactful. It is widely known that some antinutrients contained in cereal grains, such as phytate, binds to divalent minerals (i.e., zinc, iron, calcium and magnesium) compromising their absorption (29).
“Also, if you’re not careful about making lean meat choices, you’ll quickly ratchet up your risk for heart problems” .
Actually, the most recent comprehensive meta-analyses and reviews do not show fresh meat consumption whether fat or lean to be a significant risk factor for cardiovascular disease (30-34), only processed meats such as salami, bologna, bacon and sausages (30).
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