Most of us are trying to become healthier and live longer, and we rely on research to help us make decisions about what we put into our bodies. But more often than not, the research is contradictory.
The more you read, the less you know for certain!
Is red wine good for me? Please say yes. Do tomatoes cause or prevent cancer? Do whole grains really promote heart health?
WHY IS THE RESEARCH SO FILLED WITH CONTRACTION?
1. Nutrition researchers have to rely on OBSERVATIONAL STUDIES
- It’s impossible to conduct randomized trials (two groups: one gets treatment, the other a placebo) for most big nutritional questions. And Observational Studies are very valuable. That’s how we learned about the benefits of exercise and the dangers of smoking. But they’re not very precise.
- The Women's Health Initiative is one of the biggest and most expensive nutrition studies ever done. 160,000 women were randomly assigned to two groups. One was told to eat a regular diet and the other a low-fat diet. They were told to follow the diet for years. The problem? When researchers collected their data, it was clear that no one followed the diet. Basically, both groups had similar diets. Oops.
2. Many nutrition studies rely on FOOD SURVEYS
When researchers examined these "memory-based dietary assessment methods," for a paper in the Mayo Clinic Proceedings, they found that this data was "fundamentally and fatally flawed”. There are two primary reasons for this:
- First of all, there are two different types of memory required for dietary recall: specific and generic. Specific memory relies on particular episodes of eating and drinking, as in a 24-hour window. Generic memory relies on general impressions about one's typical diet. I don’t know about you, but my generic memory is not that reliable!
- Beyond that, self-reporting is susceptible to social desirability and social approval biases. This means individuals (and women more than men when it comes to nutrition) often respond in a manner consistent with expected norms.
3. Conflict of interest is a huge problem in nutrition research
- Additionally, much of the research is sponsored by corporations that make food and beverages. So it’s no big surprise that they report results that are favorable to the industry sponsor.
So what should you believe?
- Meta-Analysis: you need to consider all the available research on a question. In other words, read the results of multiple scientific studies, not just one.
- Consider the source - who is paying for the study?
- And last but not least, listen to your body. And do what feels right for you.