are avocados good for us? is dairy in or out? should we all be drinking red wine? the media supplies us with an endless list of “dos and don’ts” but the challenge is to realize that these recommendations change quickly and often contradict each other.prioritizing a healthy lifestyle can become a struggle when we don’t know where to get our information. and this is information that is particularly significant – historically, cardiovascular disease has been the
costliest disease in canada while
obesity is estimated to have an
economic burden of $4.6 to $7.1 billion annually.coronary artery disease refers to blockages in the blood vessels of the heart that can lead to heart attacks. it is the
number one cause of death worldwide. risk factors include high cholesterol, high blood pressure,
diabetes,
obesity and smoking, all of which are considered modifiable risk factors, with the first four modifiable by diet.data from the organization for economic cooperation and development tell us that almost 60 per cent of the population of member countries are overweight, with 40 per cent of these individuals classified as obese. morbid obesity, in particular, is on the rise, with morbid obesity accounting for more than 70 per cent of total obesity growth in the united states. the
heavy burden of obesity, an oecd study, says the increasing number of people who are overweight will curb gross domestic product by an estimated 3.3 per cent on average and that for every dollar spent on preventing obesity, the economic return is up to six dollars. these factors are what make having good data on diet and nutrition so important.in the scientific world, the “randomized controlled trial” is considered the highest form of primary evidence. it splits study participants into at least two groups – the “control” group, which does not receive the intervention, and the “experimental” group, which does. for example, in a randomized controlled trial examining avocados, the control group would eat its normal diet and the experimental group would consume a diet high in avocados. who is in which group would be determined by random chance, ensuring that any differences measured between the groups should, in theory, be attributable to the avocados alone. this is considered to be superior to cohort and case-control studies, case series and case reports.but even with the mighty “randomized controlled trial,” we need to be careful. as doctor, epidemiologist and writer amitha kalaichandran
puts it, “one study is just one study… if findings from one study were enough to change medical practices and public policies, doctors would be practicing yo-yo medicine where recommendations would change from day to day.” she warns that we must be wary of headlines that state “a study found” (often what we see in headlines about nutrition), as one study alone often is not enough evidence to change behaviours – study results should be replicable. red meat illustrates the “yo-yo,” garnering a bad reputation over the years, linked to health risks like heart disease and various cancers.a study published in
annals of internal medicine in 2019, however, led to news headlines on variations of the general idea that red meat is not so bad. since then, a
number of researchers have questioned the methodology and accuracy of these results, once again pushing us to believe red meats may in fact be bad for us.randomized controlled trials are generally resource intensive and difficult to conduct – randomized controlled trials relating to diet, however, are exceptionally difficult. unlike studies where the randomization is a drug versus a placebo, diets, much like human behaviours, are far more complicated, thus maintaining consistency is more difficult. given the heterogeneity, it becomes difficult to ascertain whether any differences we may detect are truly attributable to the diet in question.additionally, these trials often follow subjects for short time periods, making it difficult to extrapolate to long-term outcomes since the sustainability of these diets is called into question. these points are nicely illustrated in a
study published in jama network open indicating that 86 per cent of diet trials had a significant discrepancy from the initial registration with clinicaltrials.gov while this rang true for only 22 per cent of drug trials.also important to recognize are the stakeholders involved in making recommendations. for example, the accuracy of recommendations put forward in the latest
canada food guide, published in january 2019, was questioned by organizations like the dairy farmers of canada and alberta beef producers. unsurprisingly, the new guide deemphasizes dairy and pushes plant-based protein for a healthy diet.