Was it Ancel Keys or the low carb advocates
who fabricated data on saturated fat?
Recent reports downplaying the dangers of saturated fat have ignored a large body of relevant evidence accumulated over a century from clinical, population and animal studies demonstrating the dangers of foods rich in saturated fat. However, even evidence from the lines of research used to downplay the dangers of saturated fat strongly suggest that saturated fat increases the risk of death from heart disease.
Proponents of Paleo and Low-Carb diets suggest that plant-based diets, particularly those rich in grains and legumes, promote disease, ultimately resulting in premature death. However, there is a substantial amount of evidence casting doubt on such suggestions, with many studies providing evidence that plant-based diets increase longevity.
Grass-Fed Animal Foods and Diseases of Civilization: Cardiovascular Disease in Ancient Civilizations
Proponents of Paleo and Low-Carb diets have claimed that foods derived from naturally raised, grass-fed animals are health promoting, and protect against cardiovascular disease. However, there is a significant amount of evidence from both ancient civilizations and from the 19th and early 20th century which cast doubt on these claims.
Many traditional living populations have thrived on carbohydrate, including wheat rich diets, casting doubt on many of the claims of promoters of Low-Carb, Paleo and Primal diets. This article examines the health of these populations as well as the adverse effects of Low-Carb and Paleo diets.
2013 marks the 100th year anniversary of when Nikolai Anichkov first used the rabbit model to show that the ingestion of dietary cholesterol alone is a primary cause of atherosclerosis. This article examines the evidence surrounding dietary cholesterol and health accumulated since Anichkov's time.
A number of populations throughout Asia Pacific subsisted almost exclusively on animal or plant foods before the globalization of the western diet. This article examines the evidence of the health of these traditional living populations and how these findings provide implications for disease prevention.
Although the controversy surrounding the lipid hypothesis is considered largely resolved, controversy has lingered over the role of blood lipids on the risk of stroke. This article examines how blood cholesterol and blood pressure may influence the risk of stroke and which foods may reduce the risk.
The documentary Forks Over Knives and the book The China Study have influenced many to adopt a plant based diet, inevitably attracting the attention of advocates of animal rich diets who have criticized these works. This article examines whether many of these criticisms are actually evidence based.
Saturday, 13 December 2014
Saturday, 12 April 2014
Vegetarian Diets and Perceived Health: Cause or Effect?
Potential limitations of our results are due to the fact that the survey was based on cross-sectional data. Therefore, no statements can be made whether the poorer health in vegetarians in our study is caused by their dietary habit or if they consume this form of diet due to their poorer health status. We cannot state whether a causal relationship exists, but describe ascertained associations.
Our results have shown that vegetarians report chronic conditions and poorer subjective health more frequently. This might indicate that the vegetarians in our study consume this form of diet as a consequence of their disorders, since a vegetarian diet is often recommended as a method to manage weight and health.
...the vegetarian diet — characterized by a low consumption of saturated fats and cholesterol that includes increased intake of fruits, vegetables and whole-grain products — carries elevated risks of cancer, allergies and mental health disorders.
Vegetarian Diets and Cancer
The results of a recent study from the Netherlands illustrates the critical importance of considering reverse causality in research on plant-based diets. The researchers found that 75% of the vegetarian participants with cancer adopted a vegetarian diet after diagnosis, consistent with previous research which found that cancer survivors are highly motivated to adopt a more plant-based diet with the intention of improving poor health.3 4
Prospective (forward-looking) studies which measure diet before diseases are diagnosed are much less likely to be complicated by reverse causality than cross-sectional studies, and therefore considered to be more appropriate for determining causality. I previously carried out a meta-analysis of 5 prospective cohort studies comparing the rates of cancer incidence in vegetarians compared to health conscious omnivores. For this review, I updated the meta-analysis to include the rates of major cancers in the Adventist Mortality and Adventist Health studies. In addition, I limited the inclusion criteria to studies that provided estimates specifically for subjects classified as either vegans, or lacto-ovo vegetarians.
The finding of a decreased risk of cancer in vegetarians may be explained, in part, by a diet devoid in heme iron. Controlled feeding trials have established that NOCs (N-nitroso compounds) arising from heme iron in meat forms potentially cancerous DNA adducts in the human digestive tract, likely in part, explaining the significant association between heme iron and an increased risk of colorectal cancer in recent meta-analyses of prospective cohort studies.10 11 12 Heme iron has also been associated with numerous other cancers.
Vegetarian Diets and Heart Disease
In the Austrian Health Interview Survey, it was suggested that subjects classified as vegetarians were more likely to have had a history of heart attacks. It is important to note however, that, plant-based diets, poor in saturated fat and cholesterol have for long been adopted by individuals at risk of coronary heart disease. For example, it is known that in studies carried out as far back as the late 1950s, subjects with unfavorable blood cholesterol levels tended to limit intake of dietary cholesterol and saturated fat in order to improve cardiovascular risk factor.13
I previously carried out a meta-analysis of 7 prospective cohort studies comparing the rate of death of coronary heart disease of vegetarians compared to health conscious omnivores. For this review, I examined the incidence of coronary heart disease, and limited the inclusion criteria to studies that provided estimates specifically for subjects classified as either vegans, or lacto-ovo vegetarians. In a meta-analysis including 7 prospective cohort studies, vegetarians had a statistically highly significant 24% lower risk of coronary heart disease compared to health conscious omnivores (Fig. 2).5 6 7 14 15
|FIGURE 2. Risk ratios and 95% CIs for fully adjusted random-effects models examining associations between vegetarian diets in relation to coronary heart disease incidence. VEG, vegetarian diet.|
Vegetarian Diets and Mental Heath
The findings from a number of clinical trials cast doubt on the hypothesis that an appropriately designed flesh free diet has adverse effects on, and that flesh rich diets, poor in carbohydrate have beneficial effects on overall mental health.
- Sacks and colleagues carried out a crossover trial to examine the effects of adding 250 g/day of beef isocalorically to the diet on blood cholesterol of vegetarians. As expected, during the meat phase total cholesterol and systolic blood pressure increased significantly. However, it was also observed that the participants experienced increased anger, anxiety, confusion, depression, and fatigue and less vigor compared to the vegetarian phase.17
- Beezhold and Johnston compared the mood scores of participants assigned to either a vegetarian diet, excluding all animal foods except dairy to participants assigned to either a omnivorous diet, or a diet that included fish, but excluded meat and poultry. The researchers found that the vegetarian group demonstrated significantly improved mood scores compared to both the omnivorous and fish groups.18
- Schweiger and colleagues compared the effects of a vegetarian diet and an omnivorous diet on global mood scores. They found that the vegetarian group demonstrated significantly better global mood, and that carbohydrate intake associated with better global mood.19
- Kieldsen-Kragh examined the effects of a vegetarian diet on rheumatoid arthritis. The researchers hypothesized that the participants may find the vegetarian diet too restrictive, and that therefore adherence to the diet would impose psychological distress on the them. However, contrary to their expectations, the vegetarian group demonstrated significantly improved physiological health, and were less anxious and depressed compared to the omnivorous group.20
- Brinkworth and colleagues examined the effects of a very low-carbohydrate diet and a low-fat diet on body weight and mood and cognitive function. Although there was no statistical difference in terms of weight loss between the groups, the participants assigned to the low-fat group demonstrated significantly improved mood scores compared to the participants assigned to the low-carbohydrate diet.21
- Holloway and colleagues carried out a crossover trial to examine the effects of a high-fat, low-carbohydrate diet on alterations to heart and brain function. The researchers found that the participants not only demonstrated significantly impaired cardiac health, but also impaired attention, memory recall speed, and mood while following the high-fat, low-carbohydrate diet.22
- Halyburton and colleagues examined the effects of a low and high-carbohydrate diet on mood and cognitive function. Although, unlike other studies, the researchers found that mood was similar in both groups, participants assigned to the low-fat diet demonstrated improved speed of processing compared to the participants assigned to the low-carbohydrate group.23
Mass Media as a Source of Health Information
Although there is convincing evidence of the health benefits of an appropriately planned diet that either excludes or significantly limits the intake of flesh, such findings cannot be extrapolated to all diets that exclude flesh. The definition of a vegetarian diet only provides information as to what foods an individual restricts, and not which foods are included. This is why the emphasis of a healthy diet also needs be on which foods are included, not only on those that are excluded. Future research in this area should address what foods vegetarians are substituting meat with, the length of adherence to a vegetarian diet, and whether subjects adopted a vegetarian diet in order to alleviate poor health. This would allow for a considerably more meaningful interpretation of the effects of vegetarian diets.
Friday, 28 March 2014
More recently, Chowdhury and colleagues published a separate meta-analysis in the Annals of Internal Medicine, and reached similar conclusions to that of Siri-Tarino and colleagues regarding the association between saturated fat and coronary heart disease.7 Unfortunately, this meta-analysis also failed to sufficiently address a number of important limitations that it shares with the meta-analysis by Siri-Tarino and colleagues. Furthermore, in this meta-analysis, although positively, but not significantly associated in the random-effects model, both dietary and total circulating concentrations of saturated fat were associated with a small, but statistically significant increased risk of coronary heart disease in the fixed effects model (RR=1.04 [95% CI, 1.01, 1.07] and RR=1.13 [95% CI, 1.03-1.25], respectively). These significant findings were however ignored in the conclusions of this study. Nevertheless, the media and proponents of popular Low-Carb and Paleo diets have repeatedly cited these meta-analyses as evidence to support a diet rich in saturated fat.
Sunday, 9 February 2014
It is not news that Denise Minger has a tendency to downplay the health benefits of plant foods and plant-based diets. In her critique of the China Study, Minger claimed that “as a plant-nosher”, she was hoping to find evidence to support Dr. T. Colin Campbell's findings from the China Study linking dietary fiber to lower rates of colorectal cancer.1 Somehow, however, despite her vegan bias apparently creeping into her critique, Minger suggested that she was unable to find sufficient evidence outside of the China Study supporting the hypothesis that dietary fiber protects against colorectal cancer. And yet, several months later the omnivorous panel of experts of the World Cancer Research Fund concluded based on a review of over 1,000 publications that there was convincing evidence that dietary fiber protects against colorectal cancer.2 In Death By Food Pyramid, Minger continues this trend of downplaying the health benefits of plant-based diets.
Failing to Equal the Seventh-day Adventists
In the chapter of her book, Herbivore’s Dilemma, Denise Minger provides a brief overview of the history and the growth of the popularity of vegetarian diets, bringing into picture the earliest of the studies on the Californian Seventh-day Adventists. Loma Linda, California which is highly concentrated by Adventists is considered to be a Blue Zone because of the greater life expectancy compared to other parts of North America. Loma Linda shares the title of Blue Zone with four other populations which are all characterized by traditionally consuming plant-based diets, typically rich in legumes and grains.3 These other Blue Zones include, Ikaria, Greece; Nicoya, Costa Rica; Okinawa, Japan; and Sardinia, Italy. It seems that Minger was not even able to get these simple details right in her book, claiming that the Greek island of Crete is considered a Blue Zone, while citing an article that clearly refers to Ikaria.
A few years back, Denise Minger instantly rose to fame in the Low-Carb and Paleo diet circles shortly after publishing a blog post criticizing the chapter describing the findings from the China-Cornell-Oxford Project in the book, The China Study, written by Dr. T. Colin Campbell.1 This blog post was very welcomed by proponents of these diets as it provided them with a reference which they used to attempt to use refute much criticism they had been receiving for promoting a diet rich in animal foods.
As described previously by Plant Positive, and myself, there were a number of serious concerns with Minger’s interpretations of the data from the China Study which further casted doubt on her true intentions. One particular example was Minger's attempt to attribute the association between fat intake, a marker of animal food intake, and an increased risk of breast cancer mortality in the China Study to the consumption of "hormone-injected livestock".3 The fact that the mortality data that Minger examined was from the early to mid-1970s, a time when the use of hormone injections was not exactly widely practiced throughout rural China casts serious doubt on this claim. Furthermore, it is important to consider that the time lag between exposure to a causal agent and when breast cancer becomes life threatening is more than often several decades. For example, the greatest risk of excess death from radiation-related solid cancers, such as breast cancer among the atomic bomb survivors of Hiroshima and Nagasaki was more than half a century after exposure.4 It is therefore likely that most of the dietary related deaths from breast cancer that occurred in the early 1970s would more likely to have been caused by the diets consumed several decades earlier, likely even before hormone injections was used to any meaningful extent in China. This provides further suggestive evidence that Minger was merely trying to downplay the evidence of the harms of animal foods, rather than producing an honest review.
Sunday, 29 December 2013
In Powered By Plants: Natural Selection & Human Nutrition, Don Matesz proposes that a plant-based diet powered human evolution. Challenging anthropologists and advocates of low-carbohydrate and 'paleo' diets who claim that we require meat in our diet because meat-eating drove human evolution, Matesz cites a large body of evidence indicating that the human organism has numerous heritable anatomical, physiological, and biochemical features primarily adapted to acquisition or metabolism of whole plant foods, but lacks the heritable features expected as evidence of evolution primarily driven by meat consumption. While natural selection appears to have favored a human biology that thrives on a plant-based diet, sexual selection may explain the apparent paradox that we are athletically capable of hunting but highly susceptible to diseases caused by the luxury of meat consumption. Matesz surveys human biology from head-to-toe, and, backed by hundreds of references, shows that our sensory, locomotive, manual, digestive, and reproductive systems, and our nutrient metabolism, are all adapted to a whole foods plant-based diet. This evidence indicates that consumption of animal products promotes disease because it conflicts with basic human biology.
In this book, Matesz also examines the natural occurring pathogens found in animal foods, demonstrating that these are found in similar quantities in both intensively farmed livestock and wild game, and provides a significant amount of evidence for their role in human disease. This book is an essential read for anyone interested in evolutionary nutrition, and highly recommended for anyone interested in health in general.
Thursday, 24 October 2013
Grass-Fed Animal Foods and Diseases of Civilization: Cardiovascular Disease in Ancient Civilizations
Monday, 12 August 2013
Sunday, 7 April 2013
Our study suggests that there is a dose-response positive association between egg consumption and the risk of CVD and diabetes.
|Figure 1. Aortic atherosclerosis of a chimpanzee which died of a heart attack after long-term feeding of a diet rich in cholesterol and artery-clogging saturated fat|