The Power of Nutrition (Part 7): The Clarity of Evidence

The Baseline

In the last articles, we examined the huge impact nutrition has on global and individual health, we travelled to the Blue Zones as one of many best-practice examples regarding lifestyle, and we took a closer look at some of the most important mechanisms of nutrition in our bodies. In this last article of our “Power of Nutrition” series, we want to put those puzzle pieces of evidence together with epidemiological and clinical research as well as international guidelines to define the pattern of optimal nutrition. Such a pattern should minimize the risk of disease, optimize life quality, and extend lifetime.

Clarity

When looking at large population studies, the number of potential optimal nutrition patterns seems to be narrowed down to a few similar models. The scientific investigations of Blue Zones like Okinawa1)Willcox BJ, Willcox DC, Todoriki H, Fujiyoshi A, Yano K, He Q, et al. Caloric Restriction, the Traditional Okinawan Diet, and Healthy Aging: The Diet of the World’s Longest-Lived People and Its Potential Impact on Morbidity and Life Span. Annals of the New York Academy of Sciences. 2007 Oct 1;1114(1):434–55. or Loma Linda2)Orlich MJ, Singh PN, Sabaté J, et al. Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2. JAMA internal medicine. 2013;173(13):1230-1238. doi:10.1001/jamainternmed.2013.6473., the findings of the EPIC Oxford research group3)Crowe FL, Appleby PN, Travis RC, Key TJ. Risk of hospitalization or death from ischemic heart disease among British vegetarians and nonvegetarians: results from the EPIC-Oxford cohort study. Am J Clin Nutr. 2013;97(3):597-603. 4) Appleby PN, Key TJ. The long-term health of vegetarians and vegans. Proceedings of the Nutrition Society. 2016;75(3):287-293.  , the Rotterdam Study5)Chen Z, Zuurmond MG, van der Schaft N, et al. Plant versus animal based diets and insulin resistance, prediabetes and type 2 diabetes: the Rotterdam Study. Eur J Epidemiol. 2018;33(9):883-893., or the Nurses Health Study (1 and 2)6) Satija A, Bhupathiraju SN, Rimm EB, et al. Plant-Based Dietary Patterns and Incidence of Type 2 Diabetes in US Men and Women: Results from Three Prospective Cohort Studies. PLoS Med. 2016;13(6):e1002039. Published 2016 Jun 14. doi:10.1371/journal.pmed.1002039 all draw the same conclusion: the more unrefined plant foods one eats, the lower the risk for most diseases, among them the most common chronic diseases, like coronary artery disease, diabetes and certain cancers. Adherence to the most famous dietary pattern around whole plant foods, the Mediterranean Diet, showed a 23% reduced risk of developing type 2 diabetes7)Koloverou E, Esposito K, Giugliano D, Panagiotakos D (2014): The effect of Mediterranean diet on the development of type 2 diabetes mellitus: a meta-analysis of 10 prospective studies and 136,846 participants. Metabolism. 2014 Jul;63(7):903-11., more than a 50% lower cardiovascular risk8)Martínez-González MA, García-López M, Bes-Rastrollo M, Toledo E, Martínez-Lapiscina EH, Delgado-Rodriguez M, Vazquez Z, Benito S, Beunza JJ. (2011): Mediterranean diet and the incidence of cardiovascular disease: a Spanish cohort. Nutr Metab Cardiovasc Dis. 21(4):237-44., and almost a 50% reduction in the risk of all-cause mortality9)Zazpe I, Sánchez-Tainta A, Toledo E, Sánchez-Villegas A, Martínez-González MÁ. (2014): Dietary patterns and total mortality in a Mediterranean cohort: the SUN project. J Acad Nutr Diet. 114(1):37-47..

A meta-analysis of observational studies showed a significant protective effect of a vegetarian diet and the incidence and/or mortality from ischemic heart disease (-25%) and incidence from total cancer (-8%; vegan diet conferred a significant reduced risk (-15%) of incidence from total cancer)10) Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Crit Rev Food Sci Nutr. 2017;57(17):3640-3649.. These beneficial effects of predominantly plant based patterns are as well seen in randomized controlled trials and large meta-analyses, whether they investigate complete dietary patterns, like the DASH diet11)Siervo M, Lara J, Chowdhury S, Ashor A, Oggioni C, Mathers JC. (2015): Effects of the Dietary Approach to Stop Hypertension (DASH) diet on cardiovascular risk factors: a systematic review and meta-analysis. Br J Nutr. 14;113(1):1-15., or a whole food plant-based diet12)Mishra S, Xu J, Agarwal U, Gonzales J, Levin S, Barnard ND. A multicenter randomized controlled trial of a plant-based nutrition program to reduce body weight and cardiovascular risk in the corporate setting: the GEICO study. Eur J Clin Nutr. 2013;67(7):718-724., or single nutrients like protein (plant derived vs. animal derived)13) Li SS, Blanco Mejia S, Lytvyn L, Stewart SE, Viguiliouk E, Ha V, de Souza RJ, Leiter LA, Kendall CWC, Jenkins DJA, Sievenpiper JL. (2017): Effect of Plant Protein on Blood Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Am Heart Assoc. 20;6(12). pii: e006659. or fiber14)Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019;393(10170):434-445..

Putting these puzzle pieces together, it should come as no surprise, that the top ranked U.S. News “Best Diets” are entirely predominantly plant-based diets15)https://health.usnews.com/best-diet/best-diets-overall, (accessed March 4, 2019).. While the media oftentimes contribute a great deal to the major uncertainties regarding nutritional advice among the public, this ranking shows the real and simple clarity of evidence. Much more importantly, by currently evaluating the existing research, every single renowned medical and nutritional society around the world has come to the same conclusion. Despite alleged daily breaking news around nutrition and contradictions in the media, the guidelines of those societies leave no doubt about the fact that by far, the largest part of the daily calorie requirement should be met with unrefined or minimally processed plant foods. This is not at all a matter of scientific dispute, but the solid foundation of nutritional science, built by the extensive research of the last centuries.

Upscaling the Successful Pattern

If anything, the latest scientific findings lead to an even more consistent implementation of the outlined nutritional pattern. Current guidelines eliminate meat (USA)16)https://www.choosemyplate.gov/, (accessed March 4, 2019). and dairy (Canada)17)https://food-guide.canada.ca/en/, (accessed March 4, 2019). as food groups in their recommendations, they emphasize the selection of plant protein (USA, Canada, Belgium18)https://www.gezondleven.be/, (accessed March 4, 2019)., Germany19)https://www.dge.de/ernaehrungspraxis/vollwertige-ernaehrung/10-regeln-der-dge/ (accessed March 4, 2019). among others), they further reduce the amount of animal products (EAT/Lancet Commission20)Willett W, Rockström J, Loken B, et al. Food in the Anthropocene: the EAT–Lancet Commission on healthy diets from sustainable food systems. The Lancet. 2019;393(10170):447-492.), and they link well-planned vegetarian and vegan diets to potential additional health benefits (USA21)Craig WJ, Mangels AR, American Dietetic Association. Position of the American Dietetic Association: vegetarian diets. J Am Diet Assoc. 2009;109(7):1266-1282., Canada, Portugal22)National Programme for the Promotion of Healthy Eating Guidelines for a Healthy Vegetarian Diet, Portugal 2015; https://www.alimentacaosaudavel.dgs.pt/activeapp/wp-content/files_mf/1451330068Guidelinesforahealthyvegetariandiet.pdf, (accessed March 4, 2019). among others).

When looking at the research building the aforementioned foundation of nutritional science, it seems very plausible that the health benefits from every additional serving of whole plant foods continue to increase with a 100% plant-based diet.

Work on The Keystones

To ultimately confirm these findings, more Randomized Controlled Trials (RCT), comparing already very successful plant-based eating patterns to whole food vegan diets with regards to various clinical endpoints, are needed in all fields of medicine. In the last few years many institutions around the world did start RCTs to cover this area, and the first completed ones do look quite interesting: In a 74-week trial, comparing a low-fat vegan diet and a diet following 2003 American Diabetes Association guidelines, both diets were associated with sustained reductions in weight, plasma lipid concentrations and HbA1c. In analyses controlling for medication changes, significantly greater reductions were seen in HbA1c values and in total and LDL-cholesterol concentrations in the vegan group. As well, in their discussion, the authors highlight the seemingly different mechanisms of altering energy intake in the two different groups: “While people in the conventional group were prescribed an explicit energy deficit, a low-fat vegan diet typically elicits significant weight loss in the absence of prescribed energy intake limits. This is likely because reduced dietary fat and increased dietary fiber reduce dietary energy density”23) Barnard ND, Cohen J, Jenkins DJA, et al. A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: a randomized, controlled, 74-wk clinical trial. Am J Clin Nutr. 2009;89(5):1588S-1596S..

Another RCT took a look at the anti-inflammatory effects of a whole food vegan diet vs. the American Heart Association (AHA)-recommended diet in patients with coronary artery disease. They measured hsCRP (High Sensitivity C-reactive Protein), which is a marker for inflammation, and especially in patients with coronary artery disease a marker of high risk for adverse cardiovascular outcomes. After 8 weeks of the dietary intervention, hsCRP had dropped significantly in both groups as expected, but the vegan diet even resulted in a 32% lower hsCRP when compared to the AHA-recommended nutrition pattern24)Shah B, Newman JD, Woolf K, et al. Anti-Inflammatory Effects of a Vegan Diet Versus the American Heart Association-Recommended Diet in Coronary Artery Disease Trial. J Am Heart Assoc. 2018;7(23):e011367. doi:10.1161/JAHA.118.011367.

We Know the Problem – We Know the Solution

Combining the huge impact of nutrition on individual and global health (see Part #2: The Global Burden of Non-Communicable Diseases), the unquestionable clarity of evidence regarding the mechanisms and outcomes of plant-based nutrition patterns, and the promising and plausible work on the most consistent implementation of these patterns, we as health professionals are challenged to act on this knowledge. We do know the problem, and we do have the solution. It is time to implement it in our own lives, our daily medical practice, and our societal and political actions.

This article is part of the series “The Power of Nutrition”.

References   [ + ]

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