Forbidden Food debunks reliability of food and nutrition research is FREE to subscribers
KELOWNA, BC, Mar 10, 2015/ Troy Media/ – Forbidden Food is a provocative and entertaining book, whose author, family physician and Troy Media columnist John Sloan, is intent on debunking contemporary ideas about food and nutrition.
The book quite rightly criticizes nutrition research. Most diet and health research is observational, and many studies depend on highly unreliable self-reports of how much of what people eat. Problems abound, ranging from recall bias, to confounding, to establishing the nature of apparent associations, to poor study design, and thus findings are all over the map.
Food and nutrition studies lack credibility
Experimental studies into food and nutrition attempting to see if there are differences between one group exposed to a food component or a set of foods versus another are scarcely better. Long-term compliance by intervention group members, and secular change (a drift of eating habits among control group members), drop-outs, unclear outcome measures, and the use of proxy endpoints (seeing if blood pressure changes as opposed to looking a real health outcome such as heart attack) mean most studies struggle to find any meaningful differences, and when they do, it’s usually tiny or because of error.
Then there are the issues of understanding probabilistic data. The calculated risk to health (or health protective effect) associated with a food or nutritional component applies only to the entire population studied. It does not apply to any given individual. So if a group that eats bushels of broccoli weekly lives 10 per cent longer than a group that eats none, the statistic tells you nothing about what will happen if you begin stuffing yourself with broccoli.
The sensible answer, as Sloan points out, is probably nothing. And of course researchers goose their results telling you that there’s an impressive change of 50 per cent in deaths from “x and so”, not telling you that the chance of you dying of “x and so” is about the same as winning the lottery – i.e. the difference is so close to nil, it isn’t worth consideration.
Dr. Sloan notes the claims that we need to cut back on eggs, fats and sugars, while bulking up on fiber, enjoy next to no scientific support. His observations join recent high-quality research that shows reducing salt intake can actually increase risk of death from heart disease, over-hydration is a bigger health problem than under-hydration, and that blood cholesterol and blood glucose are not well-managed in most people through dietary intervention.
The idea of “healthy eating” is an upper middle class prejudice. Of course, malnutrition is a real threat, but it doesn’t lie with consuming processed foods, added salt, sugar or fats – although it might if you insist on bingeing on only one or two types of food to the exclusion of others. But those risks, having a restrictive diet or going overboard with a particular food, arise whether eating is centered on chicken nuggets and fries or on organic greens and brown rice.
Thus Dr. Sloan’s advice to otherwise healthy people to eat and drink what they like, but keep an eye on total calories and weight, is eminently sensible, and, in fact, completely science-based. His further advice to rely on the evidence drawn from the best quality medical literature if you are already sick is also very sensible. And so is his advice to ignore the media, the bleating and exhortations of various disease foundations, and even your family doctor, unless he or she can produce some meaningful evidence that changing your diet will really help you.
Where the book falls down is the sociology/socio-biology of eating and practices associated with it. These final chapters are speculative and dated. Dr. Sloan also fails to note developments in epigenetics, and the rather scary associations between things like restrictive diets and changes in genetic expression. He has nothing to say about the ecology of the gut and how we can cause ourselves real, irreversible damage by disturbing bacterial colonies in our colon through ill-advised dietary adventures, from weight loss dieting to fad “healthy diets”.
Forbidden Food at times too cute
Arguably, Forbidden Food would be a better book if it weren’t such a root-and-branch attack on nutritional science and health. At times, it’s a bit too cute, smug and cavalier. There are very good reasons to think modern humans are taller, more robust, and more resistant to disease due to changes in the quantity and quality of foods available to us. That’s true over centuries, but also obvious over the past 40 years in China. (18 year old boys were, on average, 5 cm taller in 2003 than in 1963. Life expectancy at birth for males moved from 45 to 75 years over the same period.) So, overall, nutrition and diet do matter, a lot, for health and life expectancy. But amounts of salt, sugar, fats, soluble fiber, anti-oxidants, wheat and much else, likely make, as Dr. Sloan contends, no difference whatsoever. This is an important message in our food-crazed, nervous, neurotic times.
Most Canadians would be wise to eat less meat and more plant-sourced foods, and almost all would be well-advised to consume fewer calories. But the core message of Forbidden Food is right: Eat widely, drink sparingly, enjoy life, be well. After all, we all will soon die of something.
Dr. Alan Davidson is a founding member of UBC Okanagan’s School of Health and Exercise Sciences.
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