Nutrition Archive

In the journals

Flavanols give fruits and vegetables their bright colors. They are also found in tea and cocoa. Observational studies have shown that eating foods rich in flavanols is linked with less cognitive decline as people age. New research suggests a possible reason why: flavanols appear to improve blood flow to the brain.

Researchers gave cocoa flavanols to 18 healthy adults in two separate trials. In one, the people consumed a cocoa drink with about 681 milligrams (mg) of flavanols. In the other, they had a cocoa drink with about 4 mg of flavanols. About two hours after having the cocoa drink, participants briefly inhaled air with high concentrations of carbon dioxide to raise their blood level above normal. (The brain's normal response to high blood carbon dioxide levels is to increase both blood flow to the brain and its uptake of oxygen.) The researchers then measured the speed of brain oxygenation and administered a set of mental tasks to assess cognitive performance. People had a faster brain oxygenation response after consuming high amounts of flavanols compared with lower amounts. They also scored higher on the cognitive tests and correctly solved problems 11% quicker.

Hamburgers, fries, sugary sodas, and other less healthy foods may cause inflammation, a key player in the formation of artery-clogging plaque.

Eating foods such as red meat and sugary treats may trigger inflammation, raising your risk of cardiovascular disease. But a diet rich in fruits, vegetables, and other anti-inflammatory foods reduces the risk, according to a large Harvard study.

"These new findings help explain why certain foods we consider unhealthy may be contributing to plaque buildup inside arteries," says Dr. Kathryn Rexrode, associate professor of medicine at Harvard Medical School and a co-author of the study, published last year in the Journal of the American College of Cardiology. Inflammation is marked by the release of molecules called cytokines into the bloodstream. These attract immune cells to artery walls, contributing to the development of plaque, she explains.

Raisins, dates, figs, and other dried fruits may not hold as much appeal as fresh fruits. But these small, sweet nuggets can be an easy way to reach your goal of eating at least two servings of fruit daily.

For one thing, they stay fresh for a long time, so you don't need to worry about spoilage. They're lightweight, making them easy to bring for snacks, and they're particularly tasty when paired with nuts. One classic combination is raisins and peanuts. Dried apricots and almonds are another nice mix.

A study published by JAMA Network Open found that people taking vitamin D supplements were less likely to have a cancer that spread from the original tumor site to another part of their body or one that proved fatal. However, this risk reduction was only seen in people who were at a normal weight, not those who were overweight or obese. The study did not find that people who took vitamin D were less likely to develop cancer over all compared with those who did not.

Sweeteners come in many varieties, including table sugar, honey, and maple syrup, high-fructose corn syrup and agave syrup. But regardless of type, from a biochemical and metabolic standpoint they are all virtually the same. Unfortunately, too much of any type is bad for one’s health.

Experts say there's little evidence that low-dose aspirin therapy brings benefits, and there are some risks.

In recent years, there's been a lot of talk about the potential benefits, and risks, of a regular regimen of low-dose aspirin. While much of the discussion has centered on whether taking low-dose aspirin can head off cardiovascular disease, some of the focus has also been on breast cancer. Can regular doses of this over-the-counter pain reliever reduce your risk of this common cancer?

For a while there were hints that the evidence was leaning that way. Back in 2017, this area of research, while still inconclusive, was somewhat promising. For example, a 2017 study published in Breast Cancer Research found that among some 57,000 women, those who reported taking low-dose aspirin (81 mg) at least three times a week had a 16% lower risk of breast cancer over all and a 20% lower risk of a specific type of hormonally driven breast cancer.

News briefs

A Mediterranean-style diet is rich in vegetables, legumes, fruits, whole grains, nuts, seeds, poultry, fish, and olive oil, and it's associated with lower risks for heart disease and diabetes. And a "greener" version of the eating style might be even more effective, according to a small, randomized study published online Nov. 23, 2020, by the journal Heart. Researchers — some from Harvard — recruited about 300 sedentary, middle-aged people (mostly men) with high cholesterol or abdominal obesity and divided them into three groups. One received guidance for exercise and a healthy diet; another received exercise guidance and was assigned to eat a calorie-restricted Mediterranean diet; and one group received exercise guidance and was assigned to eat a "greener" calorie-restricted Mediterranean diet with less animal-based and more plant-based proteins (including walnuts and a type of duckweed — an aquatic plant), plus lots of green tea. After six months, people on the "green" diet had lost more weight and inches around their middles, and had bigger drops in cholesterol, than people in the other two groups. "Green" dieters also had steeper declines in insulin resistance, inflammation markers, and diastolic blood pressure (the lower number in the measurement), compared with the other two groups.

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On call

Q. I want to avoid another kidney stone attack. What's your advice about diet, coffee, tea, and alcohol?

A. The foods you eat and the amount of fluid you drink can contribute to some types of kidney stones. Certainly, you can help prevent recurrent kidney stones by paying attention to your fluid and food intake.

Research we're watching

Diets rich in foods that trigger chronic inflammation inside the body may raise your risk of developing cardiovascular disease. A study by a team of Harvard researchers, published Nov. 10, 2020, in the Journal of the American College of Cardiology, found that people who ate more inflammation-provoking foods, like sugary drinks, red and processed meat, and refined carbohydrates, were 38% more likely to develop cardiovascular disease than those who ate a diet that helped to combat chronic inflammation. Inflammation-inhibiting foods tend to have more fiber and antioxidants, such as leafy greens, fruit, whole grains, and tea and coffee.

To come to these conclusions, the study authors looked at data from more than 200,000 women and men from three large studies, the Nurses' Health Study I and II and the Health Professionals Follow-Up Study. The participants were followed, in some cases, for more than three decades. The authors said follow-up studies will be needed to confirm their results, but their findings suggest that developing anti-inflammatory diets may help to prevent cardiovascular disease.

Bananas are one of the most popular fruits in the United States, perhaps because they're affordable (about 58 cents per pound, on average) and available year-round.

Among all fruits, bananas are one of best sources of potassium, with about 450 milligrams (mg) per banana. Healthy adults not on certain medications should aim for 4,700 mg of potassium daily, although few Americans meet this goal. A high potassium intake may help reduce high blood pressure and has also been linked to a lower risk of stroke and possibly heart disease.