The type and amount of fat, carbohydrate, sugar, and salt in our food supply has changed over the years — for better and for worse.
Remember when packaged foods emblazoned with the words "fat free" seemed to be everywhere? Then came labels boasting "zero grams of trans fat." "Sugar free" and "low sodium" claims soon joined the chorus. These days, gluten-free foods are all the rage.
For the most part, these food industry trends echoed the nutritional mantras of the time and were designed to improve our health — especially cardiovascular health. Not only is heart disease the nation's leading killer, there's overwhelming evidence that better dietary choices could prevent many heart attacks and strokes. But just how successful have these efforts been?
"It's a mixed picture, but over all, I think we're going in a good direction," says Dr. Walter Willett, professor in nutrition and epidemiology at the Harvard T.H. Chan School of Public Health. The biggest change — and greatest success story — is removal of trans fats from processed foods, he says.
The trouble with trans fats
The main source of these harmful fats is partially hydrogenated oil, a longtime food industry favorite because it's cheap, it's easy to use, and it has a long shelf life. For decades, deep-fried fast foods, baked goods, crackers, chips, and margarine were made with partially hydrogenated oils.
But in the 1990s, researchers at Harvard and elsewhere began sounding the alarm on the adverse health effects of trans fats. Trans fats raise undesirable LDL cholesterol, make blood more likely to clot, and ramp up inflammation in the body — all of which raise heart disease risk. In 2003, the FDA began requiring manufacturers to list trans fat on the Nutrition Facts label to boost consumer awareness. As a result, many companies chose to stop using trans fats in their products.
In 2007, New York City pioneered a ban on trans fat in foods sold in public eateries, and the health benefits were apparent within just a few years. One recent study found lower rates of heart attacks and strokes in the urban counties that implemented the trans fat ban compared with other urban counties in the state that did not ban trans fats.
This healthful trend should be spreading throughout the country, thanks to a long-awaited FDA ruling to ban trans fats entirely from our food supply by June 2018. "At this point, about 85% of the trans fat has been removed from our food supply," says Dr. Willett. For the most part, healthier unsaturated fats (such as those found in olive, corn, canola, sunflower, and safflower oils) have replaced trans fats. Some products now contain small amounts of less-desirable saturated fat from coconut and palm oils. However, many reformulated products cut back on trans fat without increasing saturated fat, according to a survey of 83 major-brand grocery store products and restaurant dishes.
These changes jibe with the overall improvement in fat quality in the United States, Dr. Willett notes. This trend helps explain why people who eat higher-fat diets (especially those that include more unsaturated fats) are better off than those who eat low-fat diets, as a major study by Dr. Willett and colleagues found last year.
The carb calamity
The low-fat craze that took hold in the 1980s turned out to have unintended — and very unhealthy — consequences. Following the nutrition dogma of the day, food manufacturers cut fat from their products. But they often replaced it with refined carbohydrates, such as white flour and sugar. Americans also began eating more carbs (think pasta, white potatoes, white bread, and sugary desserts). Eating less fat, however, doesn't necessarily help you lose weight. And diets high in refined carbohydrates may contribute to weight gain and promote type 2 diabetes and heart disease.
Just as is true for fats, some carbohydrates are far healthier than others. The best choices include unprocessed or minimally processed whole grains, such as whole-wheat or rye bread, brown rice, bulgur wheat, oatmeal, popcorn, and corn tortillas. Recent diet surveys suggest a slow but steady increase in whole grains in American diets. They're great sources of heart-protecting nutrients such as fiber, vitamins, and minerals.
Going against the grain?
But some grains — including wheat, barley, and rye — also contain gluten, a protein that's been getting lots of attention in recent years. "Gluten-free diets have been a big trend lately, but there is no good evidence to support these diets for most people," says Dr. Willett. Exceptions include people with celiac disease, which affects about 1% of the population. In people with the disorder, gluten triggers the body's immune system to attack the small intestine, leading to gut inflammation, pain and other debilitating symptoms. Another small group of people who report feeling better when they eliminate gluten may have "gluten sensitivity," but this condition isn't well documented.
According to a survey by the Consumer Reports National Research Center, 63% of Americans believe that a gluten-free diet could improve their mental or physical health. And up to a third of are cutting back on it in the hope that it will improve their health or prevent disease.
In fact, the opposite might be true. A recent Harvard study found that people who avoid gluten may eat fewer whole-grain foods. Also, gluten-free packaged foods may have more sugar, fat, and salt than their gluten-containing counterparts. Gluten-free diets aren't inherently bad, but the way they've been translated into the average diet isn't necessarily healthy, says Dr. Willett. People who need or want to avoid wheat should be sure to eat gluten-free whole grains such as brown rice, oats, buckwheat, and quinoa.
Sugar: Good news, bad news
The carbohydrates that pose the greatest threat to heart health are the simple, refined ones — especially sugar. High-sugar diets have been linked to a higher risk of heart disease, even in people who aren't overweight. Sugar-sweetened beverages such as sodas, energy drinks, and sports drinks contribute most of the added sugar in the average American's diet. But recent data show that consumption of sugary drinks has dropped by about 25% in the United States over the past decade, thanks in part to education campaigns and bans on soda sales in schools. This encouraging trend also seems to be slowing the growing epidemic of type 2 diabetes, which is closely linked to heart disease, says Dr. Willett.
Unfortunately, other sugar-awareness efforts are on hold. In 2016, the FDA approved a revamp of the Nutrition Facts label that would require food manufacturers to list added sugars in their products, among other changes. The rule was originally slated to take effect in July 2018, but the agency announced earlier this year that it will postpone its implementation indefinitely.
One anticipated benefit of the label change was that companies would scale back the sugar in their products, similar to what happened with trans fats. In fact, some yogurt and beverage companies have already done so. It's too early to know if this strategy will prove successful, however. Some food companies that tried removing some sodium from certain products (such as soups and vegetable juices) have now reintroduced it, says Dr. Willett. "Their competitors didn't make the change, and the low-sodium products tasted different. We really need to create a level playing field," he says.
Salt: Still too high
In 2016, the FDA proposed voluntary guidelines for the food industry to slash the amount of sodium in our food supply. Excess sodium (which pairs with chloride to form salt) is linked to high blood pressure, heart attacks, and stroke. The average American eats about 50% more sodium than nutrition experts recommend, and much of is already in their food before it reaches the table.
Time will tell if the FDA guidelines will make a difference. But a recent study suggests that we've been moving in the right direction: the average amount of sodium that households acquired from packaged foods and beverages decreased by 400 milligrams per capita between 2000 and 2014. In the meantime, see "Choosing the healthiest supermarket products" for tips on reading labels and ingredient lists while you shop.
Choosing the healthiest grocery products
When shopping for processed foods — anything bagged, packaged, canned, or bottled — check the Nutrition Facts label. Note that the Daily Value (DV) is the recommended level of a given nutrient for a person eating 2,000 calories per day.
For saturated fat, look for a % DV of 5% or less.
The same goes for sodium: % DV 5% or less.
For sugar, there is no % DV, but experts recommend that women consume no more than 24 grams daily; men should limit intake to 36 grams per day.
When selecting breads, cereals, and grain-based foods, check the list of ingredients. The first ingredient should be a whole grain, such as whole wheat (not enriched wheat). "Multigrain" just means the product includes more than one grain — and they're not necessarily whole grains.
(Harvard Heart Letter)
