A Call to End Diet Debates
Writing a science-based blog is simplified by the daily publication of new research studies. Inspiration is not the result of soul-searching rather it stems from a daily perusal of RSS feeds spewing peer-reviewed content. When the eye is drawn to a particularly compelling study, the nascence of a blog begins. At TalkingNutrition.dsm.com, our mission is to provide perspective on new research (study X shows that nutrient Y does/does not alter condition Z) by weaving these findings with other research.
Today’s blog is based on an editorial “A Call for an End to the Diet Debates” in JAMA. Pagoto and Appelhans identify two reasons for the persistent diet debate: 1) commercial interests in breakthrough diets and 2) an assumption that lifestyle interventions are ineffective. In addressing the second, they write, ‘like medical therapies, behavioral interventions should only be expected to be effective when treatment is active.” To counter this misconception, 3 lifestyle interventions (The Finnish Diabetes Prevention Study, the China Da Qing Diabetes Prevention Study, and the Diabetes Prevention Program) are cited which show persistent, long lasting effects on health outcomes years after the interventions were ended.
While our personal observations link poor nutrition and unhealthy behaviors with poor health, causality is not proven by observational data or epidemiology. The gold standard for evidence is randomized controlled trials (RCTs). When designing RCTs to elucidate causal relationships between nutrition and/or behavior with non-communicable disease, it is important to recognize that people who voluntarily choose to participate in trials fundamentally differ from those who do not. For example, in the Physicians’ Health Study, willing respondents had 1/5th lower total and cardiovascular mortality rates than nonrespondents. Nonrespondents were also the majority of the population who were approached.
Understanding the causal impact of long-term nutrition and behaviors is difficult because a placebo treatment (group) does not exist as with medical interventions. Everybody eats. Everybody has a lifestyle. Nutrition RCTs are often flawed because of a failure to assess whether the treatment intervention increased biomarkers of nutritional status. With all these shortcomings and a constant flow of new diet studies into the scientific literature which are picked up by the media, it is not surprising that people are confused.
There is a solution. Pagoto and Appelhans summarize it best, “the best approach is to counsel patients to choose a dietary plan they find easiest to adhere to in the long term. Patients should develop an appropriate physical activity program and learn behavioral modification to promote long-term adherence.”
In other words, health professionals should be nutrition and physical activity agnostic. The mission isn’t to create a ‘mini me’. The goal is to empower people to make food and/or supplement choices to nourish their bodies and minds. The goal is to help people adopt healthy lifestyle behaviors which support satisfying, active, healthier lives.
Pagoto SL, Appelhans BM. A call for an end to the diet debates. 2013 JAMA doi:10.1001/jama.2013.8601
Lindstrom J, Peltonen M, Eriksson JG, Parikka I-P, Aunonla S, Keinanen-Kiukaanniemi, Uusitupa M, Tuomilehto J. Improved lifestyle and decreased diabetes risk over 13 years: long-term follow-up of the randomized Finnish Diabetes Prevention Study (DPS). 2013 Diabetologia doi:10.1007/s00125-012-2752-5
Li G, Zhang P, Wang J, Gregg EW, Yang W, Gong Q, Li H, Li H, Jiang Y, An Y, Shuai Y, Zhang B, Zhang J, Thompson TH, Gerzoff RB, Roglic G, Hu Y, Bennett PH. The long-term effect of lifestyle interventions to prevent diabetes in the China Da Qing Diabetes Prevention Study: a 20-year follow-up study. 2008 Lancet doi:10.1016/S0140-6736(08)60766-7
Diabetes Prevention Program Research Group. 10-year follow-up of diabetes incidence and weight loss in the Diabetes Prevention Program Outcomes Study. 2009 Lancet doi:10.1016/S0140-6736(09)61457-4
Sesso HD, Gaziano JM, VanDenburgh M, Hennekens CH, Glynn RJ, Buring JE. Comparison of baseline characteristics and mortality experience of participants and nonparticipants in a randomized clinical trial: the Physicians’ Health Study. 2002 Controlled Clin Trials doi:10.1016/S0197-2456(02)00235-0
Blumberg JB, Frei B. Why clinical trials of vitamin E and cardiovascular diseases may be fatally flawed. Commentary on “The Relationship Between Dose of Vitamin E and Suppression of Oxidative Stress in Humans”. 2007 Free Radical Biol Med doi:10.1016/j.freeradbiomed.2007.08.017