Diet and Global Health

What is the single most important factor in shaping global health in the developed world? Interestingly, it does not appear to be access to the most technologically sophisticated medical technology. In the chapter on health in our textbook, I start by saying: “Chile, Costa Rica, Cyprus, Guadalupe, Hong Kong, Israel, Malta, Martinique, Singapore, and the United Arab Emirates are a diverse set of nations and territories. Yet they all have one fact in common: their citizens live longer than those of the United States, as do the citizens of many developed countries (Smallman and Brown, 2015, p. 236). Lee Miller and Weilu have an article titled “These are the World’s healthiest nations” in Bloomberg (February 24, 2019) which looks at global health statistics. The methodology looked at a number of factors -not only life expectancy- to rank countries. The top five countries were Spain, Italy, Iceland, Japan and Switzerland. There are many such rankings, and each one has methodological questions or choices. But all such national rankings of health can leave you questioning what you think you know, particularly about the role of diet in health.

In their piece, Lee Miller and Weilu talk about food, and the positive impacts of the Mediterranean diet. But I think that it is particularly in this area that such data can challenge our beliefs. Spain is number one in the Bloomberg ranking of global health. We all know that too much processed meat has consistently been shown in peer-reviewed studies to have a negative impact on health. Yet the Spanish love ham. I traveled in Spain (including Andalucia, which certainly had a Mediterranean diet) years ago, and it is one of the places that I most want to return to, particularly for the food. But I also left tired of ham. I remember sitting in a restaurant in which the ham hocks hung from every corner of ceiling, each of which had a little plastic cup hanging underneath to catch the juices during the drying process. And yet Spain’s national health ranking is very high on this study.

The role of dairy in a healthy diet has been questioned by some recent studies that link it to increased risk of prostate cancer in men, although according to one excellent study not with whole milk (Aune et al, 2014). High levels of meat consumption is also associated with an increased risk of atherosclerosis, hypertension, heart disease and perhaps colon cancer. The Swiss eat an impressive amount of meat, and in they they also consume a respectable amount of dairy (especially in the German speaking regions), particularly cheese. And yet they rank well in global health statistics.

Bangladesh may be the most vegetarian nation on the planet. It also has an disturbing rate of heart disease, for reasons that are poorly understood (Islam & Majumder, 2013). This is true even in small, rural communities which might lead a more traditional lifestyle (Zaman, et al., 2007). One study of vegetarians in rural Bangladesh found that they were deficient in some nutrients and vitamins, and recommended that they should add milk to their diet if financially possible (Farzana et al., 2013).

We all have heard the diet recommendations that are based on the best research now available: avoid too much meat, particularly processed meat, which can increase the risk of some cancers and heart disease; regular fish consumption is healthy; eat a Mediterranean diet, with more plants, including fruit, vegetables, mushrooms, beans and pulses. With milk the research is complicated, as some studies suggest that some dairy products may increase the risk of prostate cancer in men. There is also no global correlation between calcium intake and bone health (Prentice, 2014, 2014s), so it may not be particularly important to preventing fractures (but see Begum et all, 2014). On the other hand, there is some evidence that dairy protects against colon cancer, and consumption of low fat dairy benefited hypertension in one study (Prentice, 2014, 1215s). Overall, though, the evidence for a more plant-based, less processed diet is overwhelming. If you want more information, please see some of the references below. So all this is true according to the best research available. Changing how people eat would probably the biggest single positive change that could be made in most of the developed world.

And yet. This information sometimes lacks context. Popular discussions of diet sometimes remind me of an encounter I once had while in college at Queen’s University. I was talking with a man at a health fair in the Jock Harty Arena, who was smoking a cigarette at the same time he was warning me about the countless health evils of peanut butter. On YouTube and blogs, diet has become almost a cult, a single bullet that will address all health ills. People put turmeric and greens in their smoothies. Some men like me don’t put milk in their tea, because they worry that it may block the positive anti-oxidant effect that the tea has, which may help prevent prostate cancer. People scan scientific studies and watch videos to see which plants have the great health benefits of antioxidant qualities. Within limits, this is all good. But sometimes when I watch these videos I wonder why they don’t ever mention eating for enjoyment, the need for a holistic approach to health, or the limits to our knowledge.

There has recently been a a measles outbreak in the Vancouver, Washington area of the United States. If one were to look at the broader question of vaccine refusal in the United States, many of the communities that refuse these vaccines are white, privileged and well-educated. These are some of the same groups that place the greatest emphasis on diet. This does not invalidate their diet beliefs. But it does point out that health information has to be put into context. These same communities that focus on diet and health may be distrustful of Western medicine and its health tools -vaccines, colonoscopies, and medicines- which are also important to health outcomes. Even diet recommendations are sometimes taken to an extreme or based on weak evidence. One can find a plethora of websites (I won’t share them here) that say that to avoid cancer, don’t eat sugar, avoid dairy, eat organic, or adopt a paleo-diet. The underlying message is that it’s our modern diet filled with additives and food dyes that cause human cancers. If only we all ate differently.

Recently paleontologists (Haridy et al., 2019) found the fossil of a turtle from the Triassic period (240 million years ago) with an osteosarcoma. In Brazil, paleontologists (de Souza, et al, 2006) found a titanosaur (a sauropod dinosaur) with evidence of multiple tumors. A hadrosaur (duck-billed dinosaur) has also been found with evidence of cancer. A hominid skeleton from 1.7 million years ago has also been found with an osteosarcoma (Odes et al, 2016). All of these animals or hominids were certainly eating an organic diet untroubled by modern chemicals and preservatives. Cancer is an aspect of multicellular life.

I think of this because when people still have high blood pressure despite a vegetarian diet, they sometimes feel that they have failed. When people do get cancer, people may judge them. Where did they go wrong with their diet that this might happen to them? People say the strangest things to people with cancer. And yet, most cancer reflects the random increase of genetic mutations. Diet can reduce the risk of some cancers, but less so with many others. People like to have a sense of control, particularly about their health. Yet no single factor -such as diet changes- alone can guarantee good health.  We may drink our smoothies and green tea, and yet bad things still happen. It wasn’t our fault. As Shelley McGuire (2016, p. 214) notes, the World Cancer Report, 2014 had a surprising finding: “Contrary to what was previously thought, increased consumption of fruits, vegetables, and whole-grain foods is not by itself particularly helpful in lowering cancer risk.”

The point is that diet information has to be accompanied by some balance and common sense. At the risk of being repetitive, eat more plants, especially green, leafy vegetables. Don’t eat too much meat or processed foods. But also remember that much of our specific diet knowledge is often provisional. Many peer-reviewed studies on diet are infested by conflicts of interest or bias. Too often the media reports results based on small scale studies, or describe results found among cells in a petri dish. My point here is not that processed meat is not detrimental to your health, or that excessive cheese consumption is good. Both foods should be limited. There are stunning differences between the rates of prostate cancer in the United States and many Asian countries, which may perhaps be explained by diet. Still, we have to place health information in context. And to be skeptical the next time that we read media claims about the next super-food, or the one food item we should never eat. The Spanish eat a lot of ham; in Switzerland people like cold cuts, fondue, and Gruyère. Overall, they are doing wonderfully.

Shawn Smallman, 2019

References

Aune, D., Navarro Rosenblatt, D. A., Chan, D. S., Vieira, A. R., Vieira, R., Greenwood, D. C., … & Norat, T. (2014). Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies. The American journal of clinical nutrition, 101(1), 87-117.

Begum, R. A., Ali, L., Akter, J., Takahashi, O., Fukui, T., & Rahman, M. (2014). Osteopenia and osteoporosis among 16–65 year old women attending outpatient clinics. Journal of community health, 39(6), 1071-1076.

Byberg, L., Bellavia, A., Larsson, S. C., Orsini, N., Wolk, A., & Michaëlsson, K. (2016). Mediterranean diet and hip fracture in Swedish men and women. Journal of Bone and Mineral Research, 31(12), 2098-2105.

Chan, D. S., Lau, R., Aune, D., Vieira, R., Greenwood, D. C., Kampman, E., & Norat, T. (2011). Red and processed meat and colorectal cancer incidence: meta-analysis of prospective studies. PloS one, 6(6), e20456.

Crippa, A., Larsson, S. C., Discacciati, A., Wolk, A., & Orsini, N. (2018). Red and processed meat consumption and risk of bladder cancer: a dose–response meta-analysis of epidemiological studies. European journal of nutrition, 57(2), 689-701.

de Souza Barbosa, F. H., da Costa, P. V. L. G., Bergqvist, L. P., & Rothschild, B. M. (2016). Multiple neoplasms in a single sauropod dinosaur from the Upper Cretaceous of Brazil. Cretaceous Research, 62, 13-17.

Farzana, F. D., Ahmed, S., Ferdous, F., Vanderlee, L., Khan, S. H., Roy, A. K., … & Das, S. K. (2013). Biochemical and dietary indicators among vegetarians and nonvegetarians: findings from a cross sectional study in rural Bangladesh. Int J Nutr Food Sci, 2(3), 130-136.

Haridy, Y., Witzmann, F., Asbach, P., Schoch, R. R., Fröbisch, N., & Rothschild, B. M. (2019). Triassic Cancer—Osteosarcoma in a 240-Million-Year-Old Stem-Turtle. JAMA oncology.

Islam, A. K., & Majumder, A. A. (2013). Coronary artery disease in Bangladesh: a review. Indian heart journal, 65(4), 424-35.

Lu, W., Chen, H., Niu, Y., Wu, H., Xia, D., & Wu, Y. (2016). Dairy products intake and cancer mortality risk: a meta-analysis of 11 population-based cohort studies. Nutrition journal, 15(1), 91.

McGuire, S (2016); World Cancer Report 2014. Geneva, Switzerland: World Health Organization, International Agency for Research on Cancer, WHO Press, 2015, Advances in Nutrition, Volume 7, Issue 2, 1 March 2016, Pages 418–419, https://doi.org/10.3945/an.116.012211

Odes, E.J. et al. Earliest hominin cancer: 1.7-million-year-old osteosarcoma from Swartkrans Cave, South Africa. S. Afr. j. sci. [online]. 2016, vol.112, n.7-8 [cited 2019-02-25], pp.1-5. Available from: <http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532016000400014&lng=en&nrm=iso>. ISSN 1996-7489. http://dx.doi.org/10.17159/sajs.2016/20150471.

Prentice, A. M. (2014). Dairy products in global public health. The American journal of clinical nutrition, 99(5), 1212S-1216S.

Rizzoli, R. (2014). Dairy products, yogurts, and bone health. The American journal of clinical nutrition, 99(5), 1256S-1262S.

Seo, H. B., & Choi, Y. S. (2016). Sex-and age group-specific associations between intakes of dairy foods and pulses and bone health in Koreans aged 50 years and older: based on 2008~ 2011 Korea National Health and Nutrition Examination Survey. Journal of Nutrition and Health, 49(3), 165-178.

van den Heuvel, E. G., & Steijns, J. M. (2018). Dairy products and bone health: how strong is the scientific evidence?. Nutrition research reviews, 31(2), 164-178.

Zaman, M. M., Ahmed, J., Choudhury, S. R., Numan, S. M., Parvin, K., & Islam, M. S. (2007). Prevalence of ischemic heart disease in a rural population of Bangladesh. Indian heart journal, 59(3), 239-241.

 

 

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