2018 has been a year of contradictory nutrition headlines. Diets extolled by some sources were contradicted by enthusiasm for completely opposite approaches. Let’s look back at some of the year’s headlines, and consider what they mean for your healthy lifestyle.
Low-Carb or Plant-Based?
Interest has soared in potential for low-carbohydrate diets to reduce blood sugar surges after meals and demand for insulin. Elevated insulin levels seem to trigger cell signals increasing cell growth that can lead to cancer, and may also promote fat storage in the body. Some people therefore see these diets as a way to reduce risk of chronic disease and support weight loss. Achieving such low levels of carbohydrate means not only cutting out sweets and refined grains, but also limiting fruits, whole grains, and dried beans. This results in the opposite of a plant-based diet. In plant-based diets, whether vegetarian, Mediterranean or DASH-type, vegetables, fruits, whole grains and pulses (such as dried beans and lentils) occupy at least two-thirds of your plate.
Plant-based diets are at the core of recommendations to reduce risk of cancer, heart disease and type 2 diabetes. These diets provide dietary fiber that reduces high LDL (“bad”) blood cholesterol and blood sugar surges after eating, helps lower colorectal cancer risk, and probably helps avoid unintended weight gain. Moreover, these foods supply nutrients and a range of plant compounds that may play a role in supporting antioxidant and anti-inflammatory defenses.
Big Picture View: A healthy diet is not one-size-fits-all, and perhaps some people benefit from a low-carbohydrate diet. For weight loss, studies show them longer-term to be as good, but not better, compared to other options. Given the potential downside of limiting fiber- and nutrient-rich choices like whole grains, pulses and fruits, it makes sense to first work toward a more selective approach. Reserve sugar-sweetened drinks for special occasions. Reduce refined grains – swap some for whole grains if those are currently low in your diet, swap others for more vegetables or use the cut to reduce excess calories.
Gluten-Free, FODMAP and Prebiotics: How do You Feed a Healthy Gut?
Gluten-free diets are vital for people with celiac disease. Mounting evidence shows these diets may also benefit a slightly larger group of people with certain forms of irritable bowel syndrome (IBS).
Another dietary approach, low-FODMAP diets, is also gaining attention. FODMAP is an acronym for particular carbohydrates — Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols – that can cause severe gas and bloating in some people with IBS or other digestive tract disorders. Misinterpretation of information about these two diets has led to perceptions that avoiding foods with these compounds constitutes a healthy diet for everyone.
Many people choosing gluten-free or low-FODMAP diets have ended up with diets that are less healthful, as they limit variety of vegetables and fruits, reduce whole grains, and avoid most legumes (for low FODMAPs). Dietary fiber, vitamins, and phytochemicals that laboratory studies suggest may help protect against cancer and heart disease are commonly reduced. And often, consumption of refined grains and added sugars increases.
The mirror image of these diets also made headlines this year, with interest in the gut microbiome. Prebiotics are substances that selectively support specific gut microorganisms that provide a health benefit. Prebiotics include certain kinds of dietary fiber, and compounds like inulin and beta-glucans found in onion-family vegetables, dried beans and lentils, and whole grains. The kinds of carbohydrate in certain fruits that people avoid on a low-FODMAP diet also appear to be beneficial as prebiotics.
Big Picture View: For people who are truly sensitive to their effects, permanent use of a gluten-free diet, or temporary use of a low-FODMAP diet for gut healing, is recommended, limiting as few foods as possible. However, avoidance of these foods is clearly not part of a healthful diet for people who do not have sensitivity to them. An abundance of plant foods seems to promote health in multiple ways, including support of a healthy gut microbiota.
Is Weight Always a Target for Health?
Interest in the Health at Every Size perspective has continued in 2018, encouraging people to pursue healthy habits, including exercise and nutritious food choices, without weight loss as a goal. This perspective highlights the high rate of weight regain after people lose weight, and the psychological harm of shame and prejudice based on body size.
In contrast, recommendations in AICR’s 2018 landmark report on reducing cancer risk identify excess body fat as a central element of risk. Part of the association of overweight and obesity with chronic diseases may stem from lifestyle choices that promote weight gain, such as in adequate physical activity; too much sitting; and diets high in sweets, fast food and high-fat meats. However, excess body fat can have direct effects on body levels of insulin, estrogen and inflammation-promoting proteins that increase risk of cancer and other diseases.
Big Picture View: Look at weight as we do other risk factors, removed from a culture of body-shaming. Consider choices to maintain a weight that is healthy for you without restrictive diets that promote a cycle of weight loss and regain. For people with overweight or obesity, even modest amounts of intentional weight loss can produce meaningful changes in indicators of risk for cancer and other chronic diseases. And avoiding weight gain is a smart goal for people currently at a healthy weight and those who have overweight. Aim to achieve it with realistic habits that also promote health directly.