Adding science to popular diets
McMaster professor leads research on peoples’ eating habits
Sugar flakes cereal is “part of a nutritious breakfast,” and the latest fad diet is guaranteed to subtract pounds and add happiness.
The one ingredient missing from dietary promises like these is science, but research at McMaster University aims to help deliver accurate information about what we believe we are eating.
A new study, published in the journal Nutrients, saw one group of participants eat exclusively fruits, vegetables, lean meat and whole grains (the “Prudent diet”), while a second group feasted on processed foods, trans fats, red meat and sweet drinks (the “Western diet”).
Philip Britz-McKibbin, a professor of chemistry and chemical biology at McMaster, led a team of researchers — “diet detectives,” he called them — who identified chemical signatures, called metabolites, in the participants’ blood and urine, to measure changes in eating patterns involving two contrasting diets.
Employing biochemistry to evaluate a healthy diet might not seem like a new approach, but it is exactly that in the world of fad diets, where most are based on weak science at best.
Britz-McKibbin, who has taught at McMaster for 15 years, and conducted postdoctoral work in Japan, talks about the study, and fad diets including the anti-butter craze of the 1980s and the keto diet now in vogue. The participants in your study all lived in the Hamilton area? That’s right. It was a two-week dietary intervention study, and we analyzed samples from 42 participants. Blood and urine samples were collected at baseline, and then after two weeks of food provisions; participants were provided bulk food items reflecting either a Prudent or Western diet from Fortinos, which they had to cook themselves at home. It was a cool study, we had a free-living population, not a lab study. We saw that some of the biomarkers associated with a healthy Prudent diet would increase after two weeks, whereas other compounds increased only after eating a Western diet. It was a twoweek study, and didn’t take long to see profound effects we could objectively measure, which also correlated well to self-reported diet records. Give me an example of a couple of compounds. Typically small molecules we measure. From the study, one good example, proline betaine; this compound is a perfect dietary marker, not produced by the body, comes from external source, and tends to be prevalent in citrus fruits. So in that case, a nice marker of fruit intake, which tends to be healthy. There have been many fad diets and their authors often simply point to whether you lose weight to measure success. But there’s more to a healthy diet than how many pounds you can drop in a month, correct? Well sure, and that gets at the controversy with the (lowcarb/high fat) ketogenic diet popular now for weight loss; I think there are concerns for the long-term repercussions of inflammation and other negative cardiovascular effects. It’s complicated, you have to look at multiple outcomes … The biggest scandal in the past several decades was the “diet heart” hypothesis, this notion in the ’80s and ’90s about reducing cholesterol and having basically a low-fat diet to reduce obesity. It had the opposite effect: They reduced the fat content in many foods and increased the sugar content, and that exasperated the public health crisis. It’s one example of many, where studies that are not well-documented or validated are rushed into the public. You have said the next step with your research is expanding it to include pregnant women, to research diet on fetal development and the mother’s health. It is ongoing, we have analyzed blood samples from over 1,000 pregnant women across Canada. We are doing this study to more accurately assess maternal nutrition to see how it correlates with birth outcomes up to five years later. Early intervention during pregnancy is optimal to prevent chronic disorders, such as childhood obesity and Type 2 diabetes, which can also lead to more effective nutritional policies for public health. From what you’ve seen in your research, what do you think in general is the best type of diet for most people? The Prudent diet, as the name suggests, is the sensible balanced diet, focused on increasing fresh fruits and vegetables, reducing salt intake, increasing fibre, lean protein intake and reducing processed food intake. And not essentially eliminating a whole class of foods in your diet. Apart from the processed food, and anything that is heavily processed or modified, typically. One issue is that some people find it tough to afford to eat healthily, to pay the prices for food on the outside aisles, the organic section and so on. Yes, and maybe part of it is the marketing, and a change in consumer behaviour and habitual dietary habits will force manufacturers to offer better and higher quality foods that are also convenient to eat.