Welcome to the new rules of eating. (Illustrations: Elliot Salazar)
It seems like nutrition experts are always changing their minds about the best way to eat. That’s partly because the nature of science is constant exploration; the scientific method is about continually testing, refuting, and revising hypotheses, not coming up with one definite answer and staying there.
Another, deeper issue with nutrition science is how we conduct it. Randomized, controlled trials (RCTs) are the gold standard of health research, because they are the only type of study that can determine a causal relationship between an intervention (e.g. a low-fat diet) and an outcome (e.g. incidence of heart disease). But, RCTs are especially difficult to conduct in nutrition because they require people to accurately report their food intake and adhere to strict diets, sometimes for long periods of time (and we all know how that usually goes).
Instead, much of what we know about nutrition is based on evidence from observational studies, which can only tell us about associations (e.g. high trans fat intake is associated with a higher incidence of cardiovascular disease) — not about causation. Sometimes, these studies gain momentum: Dietitians and other health experts start discussing them, journalists report on them, and before you know it, the data are taken as fact before all the facts are in.
Given these issues with the science, it’s only natural that nutrition guidelines would be constantly changing. That said, some sound ideas about nutrition have emerged from decades of observational research coupled with results from RCTs. So, what nutrition advice can we actually trust right now? The 7 ideas that follow are a good start. They’re culled from the best available science to date in this ever-changing landscape.
The research now overwhelmingly shows that you don’t have to worry about total fat in your diet — it has no relationship to major health problems such as heart disease or colorectal cancer. In fact, this up-to-date thinking might make its way into the federal guidelines this year: According to the 2015 Dietary Guidelines Advisory Committee report, “dietary advice should put the emphasis on optimizing types of dietary fat…not reducing total fat.” (Whether this makes it into the final draft of the Dietary Guidelines remains to be seen; the public comment period is open until April 8.)
We could also potentially see recommended limits on saturated fat start to ease up in coming years: Some of the latest research is showing that saturated fat may not be the heart-health enemy we once thought it was. One 2014 meta-analysis of saturated fat consumption and heart disease had some controversial errors, but other experts and studies have subsequently supported the need to reexamine the saturated fat recommendations. James J. DiNicolantonio, PharmD, a cardiovascular research scientist at Saint Luke’s Mid America Heart Institute and the associate editor of the journal BMJ Open Heart, recently wrote an editorial arguing that replacing saturated fats with carbohydrates or certain types of polyunsaturated fat (such as corn and safflower oils) does more harm than good. As he explained in an email to us, “eat Real Food (regardless of whether it contains saturated fat) and you will do just fine.”
Many dietitians have been saying this ever since the gluten-free fad began, because avoiding gluten could cause you to miss out on important nutrients, eat lots of refined grains, and may even set you up for disordered eating. Recent research has shed new light on why eliminating gluten is not the answer to everyone’s health issues. A seminal 2013 study found that “non-celiac gluten sensitivity” — the technical term for what people often call “gluten intolerance” — did not appear to be caused by gluten at all. Instead, the study subjects responded favorably to a diet low in a specific class of carbohydrates called FODMAPS, and their symptoms didn’t return when gluten was re-introduced. Since that study, other researchers have wondered whether people with non-celiac gluten sensitivity actually have a form of irritable bowel syndrome, and if they would benefit from treatments other than restricting gluten. Expect to see more research that clarifies the issues and pushes back on the gluten-free trend.
Increased public awareness of calories made many people wary of snacking. But now, snacks are back — and we’re not talking about those 100-calorie snack packs. These days, nutrition experts are much more likely to recommend nutrient-dense snacks that include a combination of protein and healthy fats. “Instead of evaluating snacks based on the number of calories in a packet, consider the nutrient return,” suggests Janet Helm, RD, a registered dietitian and author of the blogNutrition Unplugged. She recommends foods such as nut butter with whole-grain crackers, hard-boiled eggs, yogurt, or small servings of cheese — all of which provide protein, to help keep you full.
Instead of focusing on individual nutrients, put an emphasis on making whole and minimally processed foods the basis of your diet. “That means shifting your focus — not demonizing or worshipping any single nutrient,” says Helm. “We can’t fully blame saturated fat. We can’t single out gluten. It’s your total diet that counts.” This shift in thinking can be seen in the2015 Dietary Guidelines Advisory Committee report and in recent research.
Lately, there’s been an explosion in scientific research on mindful eating. The evidence shows mindfulness is helpful in reducing overeating, whether full-blown binge-eating disorder or garden-variety mindless munching. (Results for weight management are mixed, however.) Mindful eating involves learning to recognize cues of physical hunger and fullness in order to make decisions about what and how much to eat. It’s also about choosing foods for nutrition and pleasure, focusing on the food (and not doing anything else) while eating, and learning about the consequences of mindless eating.
Fermented foods such as kimchi, sauerkraut, and tempeh are on everyone’s nutrition-trend lists. These foods may be beneficial for the microbial environment in the human gut (a.k.a. the microbiome or microbiota) — and scientists are discovering that the makeup of your microbiome could play a role in whether or not you’re at risk for certain chronic diseases. It’s not just fermented foods that could affect the balance of microbes in your gut, though; the latest research has shown that people who consume high-fiber, plant-based diets havedistinctly different microbiota than people who consume a typical “Western” diet that’s high in protein and fat. We continue to see more research on the microbiome — and a growing interest in eating to support it.
David Katz, MD, MPH, director of the Yale University Prevention Research Center, says this fixation on the microbiome is “a bit silly,” because the real goal is the health of the person, not the health of the microbes. But, he explains that the two are indeed linked. “So, all of the evidence we have for diet and health remains relevant; we now just know that it must also have favorable effects on the microbiome, because that is one of the mechanisms of our own health.”
Health experts may recommend certain guidelines, but that doesn’t mean they follow them 100% of the time. “We all need to eat more whole grains; this is true,” Helm wrote in a blog post about nutrition rules worth breaking. “However, that doesn’t mean you need to totally banish white bread, pasta, or rice from your diet… In moderation, white or refined grains are not ‘toxic’ and you shouldn’t feel guilty when you eat them.” As the field of nutrition starts focusing more on the diet as a whole rather than singling out certain nutrients, we’ll see more emphasis on acknowledging that it’s okay not to eat “perfectly” all the time.
By Christy Harrison, MPH, RD, CDN
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