Nutrition Archive

News briefs

Eating food that's ultra-processed — not just chips or cookies, but also things like breakfast cereal, deli meat, or canned fruit in syrup — makes people overeat and gain weight, compared with eating food that's unprocessed. That's according to a small randomized controlled trial published online May 16, 2019, by Cell Metabolism. It involved 20 men and women who stayed at a research facility for a month and were randomly assigned to one of two diets. One group was given ultra-processed foods (such as a breakfast of a bagel with cream cheese and turkey bacon), and the other group was fed unprocessed foods (such as a breakfast of oatmeal with bananas, walnuts, and skim milk). After two weeks, participants were switched to the opposite diets. Both diets were evenly matched for total calories, macronutrients, fiber, sugars, and sodium, and participants were allowed to eat as much or as little as they wanted. But they ate more calories when they were eating ultra-processed foods, compared with when they ate unprocessed foods, and they gained more weight on the ultra-processed diet. Why? It's not exactly clear, but researchers did find that appetite-suppressing hormones decreased and hunger hormones increased when people ate processed foods. Bottom line: Eat whole, unprocessed foods with as few ingredients as possible.

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How many daily calories do you really need? It depends on many factors.

When it comes to nutrition, calories embody the ultimate love-hate relationship. Consume too little, and you don't have the energy to function at your best. Eat too much, and you risk weight gain. It's no surprise, then, that counting calories can be such an obsession.

But how much do you really need every day? Unfortunately, there is not a single, simple answer. Men ages 50 and older require 2,000 to 2,800 calories per day, or an average of about 2,500, says Dr. Qi Sun, associate professor in the Department of Nutrition at the Harvard T.H. Chan School of Public Health.

In the journals

Another way to lower LDL (bad) cholesterol levels? Eat more soy protein, suggests a study published online April 22, 2019, by The Journal of Nutrition.

Researchers examined 43 trials to evaluate the effect soy had on LDL levels. (High LDL levels can lead to a buildup of cholesterol in arteries and increase a person's risk of cardiovascular disease.)

Eating too much salt usually boosts blood pressure, but not in everyone. Understanding the genetic basis of these differences may improve treatment of high blood pressure.

Do you know someone who eats lots of salty food — pizza, pickles, pretzels, and the like — but has naturally low blood pressure? That person may be salt-resistant, which means his or her blood pressure doesn't rise very much in response to a diet high in salt (sodium chloride). In contrast, other people are salt-sensitive, which means their blood pressure rises by 5 points or more if they switch from a low-sodium to a high-sodium diet.

Unfortunately, there isn't an easy test to determine who is salt-sensitive, says endocrinologist Dr. Gordon Williams, professor of medicine at Harvard Medical School. "Still, we know that Americans eat far more salt than they actually need, so it makes sense to advise everyone cut back on salt," he says.

The most commonly eaten type of bean in the United States, pinto beans are especially popular in southern states, where they may be known as frijoles (Spanish for "beans") or cowboy beans. These oval, tan-colored beans are mottled with reddish-brown streaks, making them appear painted (pinto means "painted" in Spanish).

Once they're cooked, the colored splotches disappear, leaving a light-brown bean with a soft, creamy texture. In Mexico, Central America, and South America, pintos are cooked with epazote, an herb that purportedly helps reduce the flatulence-producing properties of these and other beans. Another tip for avoiding that problem is to add beans to your diet gradually and eat them regularly.

Research we're watching

A plant-focused diet long touted for its ability to lower blood pressure may also help prevent heart failure, according to a new study.

The DASH diet, which stands for Dietary Approaches to Stop Hypertension, emphasizes fruits, vegetables, whole grains, low-fat dairy products, poultry, fish, and nuts while minimizing salt, sugar, and red meat consumption.

Q. I keep reading that peanut butter is a healthy food. But it contains saturated fat and has more sodium than potassium. That doesn't sound healthy to me. Is peanut butter good for you?

A. The presence of saturated fat doesn't automatically kick a food into the "unhealthy" camp. Olive oil, wheat germ, and even tofu — all "healthy" foods — have some saturated fat. It's the whole package of nutrients, not just one or two, that determines how good a particular food is for health.

There's no mercury to worry about, and flaxseed oil  does contain omega-3 fats...but not the best kind.

Troll the medical literature, and you'll come up with study after study showing that fish and fish oil are good for us, especially for our hearts but maybe also for our moods and immune systems. Various epidemiologic investigations have found that people who eat fish regularly are less likely to have heart attacks, suffer strokes, or die from sudden cardiac arrest. The definition of "regularly" varies, but it usually means at least a couple of times a week, although eating fish even once a month has been shown to make a difference.

Fish, and especially fish oil, have also been the subject of dozens of randomized clinical trials, most involving people with existing heart conditions. In large amounts (several grams a day), fish oil has been shown to nudge various cardiac risk factors ("good" HDL cholesterol, triglycerides, blood pressure) in the right direction.

Stop aiming for a particular amount of servings in each food category and focus on total daily intake.

Trying to hit the mark on a healthy diet can be challenging. You need to eat enough of the right foods to meet your body's vitamin and mineral needs.

Experts have tried to guide us over the years by recommending goals of daily food servings — such as five to eight servings of fruits and vegetables per day. But your idea of serving sizes may differ from someone else's. That's led to confusion and, now, change.