In 20+ years of writing about health, I’ve probably seen hundreds of headlines making conflicting claims about eggs — boomeranging back and forth between bad for LDL cholesterol and don’t eat them if you’re diabetic, to perfectly okay for most people, not to mention a good source of nutrients such as vitamins D and B12.
And that’s just one food. No wonder people start tuning out that kind of ‘news’.
The truth is that it’s incredibly difficult, if not impossible, to study the long-term effects of eating a single food. There are all kinds of reasons for this, starting with the fact that it’s not practical to randomly assign people to two groups eating an identical diet, with one getting, say, an egg a day, while you watch over them in a controlled environment for 10 years.
Another problem: a lot of the research that does exist relies on people self-reporting what they eat from memory, which is bound to be riddled with inaccuracies and omissions.
By necessity, much nutrition research is based on observational studies, rather than randomized controlled trials. Lack of randomization means any difference that’s detected could be due to factors that are completely outside of those researchers looked at.
Take the hundreds of observational studies linking hormone replacement therapy with better health outcomes, such as lower risk of heart disease — results that were blown out of the water by a large randomized controlled trial. It’s likely that women in the observational trials who were taking HRT on the advice of their doctors, were also more likely to follow their other health recommendations versus participants who didn’t take hormones.
That said, science is constantly evolving, and we actually have an accumulation of good evidence that certain eating patterns are linked with a lower risk of many ills, starting with heart disease, which is still the leading cause of death in Canada. And findings from a large body of research can nearly never be negated by a single study.
Unfortunately, that fact often gets overlooked in media coverage of the latest published paper, and social media posts promoting a particular supplement or diet.
Confused about whether butter is still a bad guy when it comes to heart disease risk? Or if warnings against eating eggs are all they’re cracked up to be?
My heartfelt thanks to the interviewees who so generously shared their time and expertise:
- Andy Bellatti, a registered dietitian in Las Vegas.
- Timothy Caulfield, Canada Research Chair in Health Law and Policy, Trudeau Fellow and professor in the Faculty of Law, and School of Public at the University of Alberta in Edmonton. He’s also the author of many books, the latest being, Relax Dammit: Healthy & Happy in the Age of Anxiety.
- Patricia Chuey, a registered dietitian and food and nutrition writer on Vancouver Island, BC.
- Andrea D’Ambrosio, a registered dietitian with Dietetic Directions in Kitchener, Ont., who spoke to me on behalf of Dietitians Canada.
- Dr. Yoni Freedhoff, an associate professor of family medicine at the University of Ottawa, and medical director at the Bariatric Medical Institute. He’s also the author of The Diet Fix: Why Diets Fail and How to Make Yours Work, as well as a prolific blogger (Weighty Matters) and health columnist.
- Dr. Len Piché, PhD, a professor emeritus of foods and nutrition at Brescia University College in London, Ont.
- Rosie Schwartz, a Toronto registered dietitian, food and nutrition writer, proprietor of Nutrition Guidance Services, and author of The Enlightened Eater’s Whole Foods Guide.