From the abstract conclusion of Association Between Dietary Whole Grain Intake and Risk of Mortality:
“These data indicate that higher whole grain consumption is associated with lower total and CVD mortality in US men and women, independent of other dietary and lifestyle factors.”
“These results are in line with recommendations that promote increased whole grain consumption to facilitate disease prevention.”
False. This conflates correlation and causation. The correlation tells us nothing about whether consuming whole grains has a positive effect on health, or whether those with better health choose to eat more whole grains, or some other mechanism is in place to explain the correlation. The data from this study cannot even disprove the hypothesis that whole grains are detrimental to people’s health. How can that be? Let us delve into deeper detail.
To clarify my beliefs, I am believe that grain consumption can be health promoting for some, perhaps many or most, people some of the time given some caveats such as:
- the grains are high quality (nutrient dense, pesticide free, etc)
- the grains are properly prepared (by soaking, sprouting, fermenting, etc)
- the person eating the grains has the digestive capacity for consuming them
There are people who label grains as intrinsically detrimental to people’s health. I do not share that belief. However, this study seems, to me, to be a rebuttal of those critiques, and a poor one at that. So what is the problem?
The major problem is that the data comes from the Nurses’ Health Study and the Health Professionals Follow-Up Study. I don’t want to disparage these studies because I think they are important and that the people involved are truly interested in increasing the knowledge and understanding of human health. However, these populations have an obvious bias toward existing health guidelines. These are populations who are much more aware of the existing guidelines and those who choose other health promoting activities are likely to follow those guidelines. So, are the behaviors being studied, in this case whole grain consumption, actually health promoting on average? Or is it that people who choose other health promoting behaviors choose to eat more whole grains because that is believed, by them, to be health promoting? This study cannot answer those questions.
Furthermore, it could be possible, though I do not believe this is the case, that eating whole grains is detrimental, on average, to human health and for this correlation to still exist. Imagine that grains are harmful but the people who are taking the best care of themselves in these study populations choose healthy behaviors that mitigate the detrimental effects of whole grains. So these people have lower mortality despite the harm of grains, and if they chose to avoid whole grains (presumably replacing them with something healthy) their mortality would decline even further. Again, I don’t believe this is the case but the only way to gain evidence supporting or opposing this hypothesis is to perform a randomly controlled trial.
So why spend so much time writing about this research? I believe it is important to begin a dialogue about the need for a higher standard of published research and policy recommendations. Probably one of the foremost goals of people who are in the position of providing information about matters of human health is that they do not overstate the conclusions beyond what the research can support. In this case, the research does show an association, but it tells us nothing about the nature of that association and thus any statements which suggest an understanding of the nature of the association are invalid. People deserve a higher standard from researchers, reporters, and policy makers than what they are currently getting.