The results of a clinical trial reported in yesterday’s Annals of Internal Medicine showed that low-carb diets helped people lose weight better than low fat diets. A report in today’s Journal of the American Medical Association tells a somewhat different story. A review of 48 head-to-head diet trails showed that average weight loss on either a low-carb or low-fat diet for 12 months was the same, about 16 pounds. And when the researchers compared named diets, which ranged from the low-carb Atkins and South Beach diets to moderates like Weight Watchers and Jenny Craig and low-fat approaches like the Ornish diet, all yielded similar weight loss. The main message from careful comparisons of different diets is that there’s no single diet that’s right for everyone. Any healthy diet can help people lose weight. And there’s more to a diet than weight loss. What’s needed for long-term health is an eating plan that can be followed day in and day out that is good for the heart, bones, brain, and every other part of the body. One eating strategy that can provide all that is the so-called Mediterranean diet.
We often look to science to solve life’s difficult questions. But sometimes it hands us more uncertainty. Take three reports in today’s New England Journal of Medicine. One shows that eating less sodium (a main component of salt) could save more than a million lives a year worldwide. A second came to a nearly opposite conclusion — that current average sodium intake is okay for cardiovascular health while getting either too little or too much is a problem. The third study essentially agreed with the second, but found that getting too little potassium may be as bad as getting too much sodium. The findings are certain to fuel the already heated debate on sodium and the international efforts to get people to take in less of it. But until there are good answers to the questions raised by the studies, it’s too soon to throw out recommendations to reduce sodium intake, especially in high-risk groups. Another lesson from the three New England Journal articles worth keeping in mind: getting more potassium from fruits, vegetables, and other foods is a good way to help keep your heart and arteries healthy.
People who want to follow a healthy diet sometimes need a little help knowing where a meal or snack falls on the healthfulness scale. Several apps let you snap a photo of what you’re about to eat and post it for all to see — and rate. And though many of the “raters” are regular folks without training in nutrition, a new study shows they do a pretty good job gauging whether foods are likely to make you fitter or fatter.
An report in this week’s Proceedings of the National Academy of Sciences calculates several environmental costs of raising cows for meat and milk, poultry and pork for meat, and chickens for eggs. According to the report, per calorie of food that we consume, dairy, poultry, pork, and eggs have similar environmental costs. Compared with their average, beef production generated five times more greenhouse gases, needed six times more fertilizer and 11 times more irrigation water, and used 28 times the land. The same four costs for growing potatoes, wheat, and rice were two-fold to six-fold lower than the nonbeef foods in land use, greenhouse gas emissions, and fertilizer use, and about the same for irrigation water.
Every day, millions of Americans use the Nutrition Facts labels on food packages to make healthy choices. The U.S. Food and Drug Administration has recently proposed changes to make the labels even more useful. It’s an important move that could help curb the skyrocketing number of Americans with type 2 diabetes, osteoarthritis, and other weight-related conditions. The proposed new label will list information about added sugars, update daily values for sodium and dietary fiber, list the amount of potassium and vitamin D, and remove the “Calories from Fat” category while continuing to list types of fat. For foods that come in larger packages but could be consumed in one sitting, manufacturers would have to use a two-column label showing calorie and nutrition information for both a single serving and the entire package. These changes are a step in the right direction, but don’t go far enough with sugar, ingredient listing, and nutrient claims.
A study published in this month’s Journal of Nutrition suggests that drinking caffeinated beverages, having the occasional alcoholic drink, and eating a healthy diet may help preserve memory and thinking skills long into old age. In particular, foods that are part of the Mediterranean diet—fruits, vegetables, nuts, fish, olive oil, and whole grains—show promise for preserving memory and preventing Alzheimer’s and other forms of dementia.
A new study that linked eating more protein to lower risk of stroke isn’t the last word on the subject. But that doesn’t make dietary protein any less vital, especially in older adults who are at greater risk for malnutrition and illness. How much protein is enough? Current guidelines for adults of any age recommend 0.8 grams of protein per kilogram of body weight. Do older people need more protein than younger ones? That’s still an open question.
Resveratrol, an antioxidant found in red wine and certain foods, has been touted as a natural way to slow aging and fight cancer, obesity, heart disease, and diabetes. As promising as it sounds, we don’t really know how resveratrol affects humans, since most studies have been conducted on animals and microbes. A study out this week from the Johns Hopkins University School of Medicine found no link between consumption of resveratrol from food and rates of heart disease, cancer, and death in a study of older men and women living in Italy’s Chianti region. The disappointing results don’t mean that resveratrol and other molecules like it won’t help extend the lifespan or protect against the development of aging-related diseases. Higher doses may be needed to do that. What’s needed now are trials to determine if taking high-dose resveratrol supplements is safe.
Fish and shellfish are great sources of lean protein, and many types are rich in heart-healthy omega-3 fatty acids. But there’s a catch: some species of fish contain worrisome amounts of methylmercury, a toxin that’s especially dangerous to developing brains. That’s why women who are or could become pregnant and young children shouldn’t eat high-mercury fish such as swordfish, shark, king mackerel, and tilefish. A new study hints that eating too much—or the wrong kind—of salmon and tuna can also boost mercury levels. But the study also offered reassurance: 95% of the nearly 11,000 people surveyed, including those who ate fish often, had blood mercury levels in the safe zone.
A sugar-laden diet boosts the chances of dying of heart disease even among people who aren’t overweight. So says a major study published online this week in JAMA Internal Medicine. Over the course of the 15-year study, individuals who took in 25% or more of their daily calories as sugar were more than twice as likely to die from heart disease as those whose diets included less than 10% added sugar. Overall, the odds of dying from heart disease rose in tandem with the percentage of sugar in the diet—and that was true regardless of a person’s age, sex, physical activity level, and body-mass index (a measure of weight). Sugar-sweetened beverages such as sodas, energy drinks, and sports drinks are by far the biggest sources of added sugar in the average American’s diet. They account for more than one-third of the added sugar we consume as a nation. Other important sources include cookies, cakes, pastries, and similar treats; fruit drinks; ice cream, frozen yogurt and the like; candy; and ready-to-eat cereals.