Our understanding of nutrition is always expanding and shifting. Here’s a look at the top nutrition revelations of the past decade.
1. Our genes and diet are related
The completion of the Human Genome Project helped give rise to nutrigenomics, the science of how the nutrients we consume impact our genes.
“We now know that certain cancers, cardiovascular disease and other chronic diseases that accompany aging can be prevented or delayed by matching our diets to our individual genomes,” says Patrick J. Stover, Ph.D., professor and director of the Division of Nutritional Sciences at Cornell.
But before you go running to your doctor or dietitian for a genetically prescribed diet, know that “there are still many challenges in classifying people by their genotype and designing a food system that can provide an individualized prescriptive diet,” says Stover.
2. Not all fat is bad fat
Today, research suggests that avoiding all fat isn’t a great idea. The type of fat matters, though.
At the end of the 20th century, “low fat” seemed to be the ubiquitous mantra, but today, research suggests that avoiding all fat isn’t a great idea.
“Cutting too much fat out of your diet can raise triglycerides and decrease healthy HDL cholesterol, which are both risk factors for heart disease,” says Penny Kris-Etherton, Ph.D., R.D., a distinguished professor of nutrition at Pennsylvania State University. “Instead, aim for about 30 percent of fat from calories.”
The type of fat matters, though. For optimal health, experts now recommend choosing mostly unsaturated fats (think: liquid vegetable oils, nuts and avocados).
3. A calorie isn’t just a calorie
You’ve heard it a million times: to stay weight-stable, calories in must equal calories out. Now we’re learning that may not always be the case.
In a recent Food & Nutrition Research study, researchers asked volunteers to eat either a sandwich made with multigrain bread and Cheddar cheese or one made with white bread and processed cheese, and found that the volunteers used nearly twice as many calories to break down the multigrain sandwich.
The reason: our bodies handle processed and unprocessed carbohydrates differently.
“When you use a machine to strip away the bran, husk and fiber from carbohydrates, that machine is essentially expending energy that your body would normally use to break down those food components,” says study co-author Jonathan Wright, Ph.D., a professor of biology at Pomona College.
4. Food sensitivities aren’t all in our head
Twenty years ago, if you told your doctor that eating foods like bread made you feel sick, he or she would likely have told you it was all in your head.
Today we know roughly one percent of Americans have celiac disease, an autoimmune disorder that causes the small intestine to be damaged by gluten in grains like wheat, barley and rye. And some estimates suggest that up to 20 million Americans (six percent) suffer from gluten sensitivity, which can cause abdominal bloating, concentration difficulties and fatigue.
5. We need more vitamin D than we thought
While we once thought vitamin D deficiency was only a problem for people living in northern latitudes, experts now estimate that three out of four Americans don’t get enough vitamin
D. Michael F. Holick, Ph.D., M.D., director of the vitamin D, skin and bone laboratory at Boston University School of Medicine, recommends a three-pronged approach for most people.
First, eat D-rich foods, such as wild-caught salmon, UV-exposed mushrooms and fortified dairy and orange juice. Second, get 10 to 15 minutes of sun on your arms and legs sans sunscreen three times a week during spring, summer and fall.
Finally, take a supplement of 1,500 to 2,000 IU of vitamin D3 each day.
6. There’s one more reason to avoid BPA
The synthetic chemical bisphenol-A (BPA) can be found metal food-can linings, food-storage containers, recycled paper and cash-register receipts. Science has linked BPA to early puberty, reproductive irregularities and cardiovascular and neurological damage.
Now, a growing body of research suggests it may be making people heavier.
Experts suspect that BPA promotes weight gain by stimulating the pancreas to rev up its production of insulin, leading to increased blood sugar levels and decreased insulin sensitivity.
7. How we get our nutrients matters
Recent research reveals dietary supplements can’t match the disease-preventing power of food.
“In their natural form, nutrients in food—like vitamins, minerals and phytochemicals—are present in specific, balanced concentrations and work together in a highly synergistic way,” says Manuel Villacorta, M.S., R.D., author of Eating Free.
Consider avocados: they’re rich in heart-healthy fats as well as vitamin E, a nutrient that requires fat for absorption. While you could get vitamin E from a pill, you can’t absorb it without the fat that nature conveniently packaged in the avocado.
8. Dietary cholesterol isn’t so evil
Years ago, if you had a cholesterol problem you were under strict orders to avoid cholesterol-rich foods like eggs and shrimp. Today, we know these foods are fine to eat in moderation.
We know now that limiting saturated fat is far more important than axing all cholesterol from your diet. Keep your numbers in check by eating seven percent or less of your calories from saturated fat (that’s 16 grams daily for a 2,000-calorie diet).
The American Heart Association recommends limiting cholesterol from foods to 300 milligrams a day (that’s one and a half large eggs or, if you can believe it, 34 medium shrimp).
If you have—or are at risk for—heart disease, cap cholesterol at 200 milligrams and saturated fat at five to six percent of your total calories.
9. We’re eating too much sugar
Too much sugar spells bad news for our waistlines—and our health. Banish all sweetened drinks and any processed foods high in added sugars.
In the past 40 years, the amount of added sugars in our diets has skyrocketed. All that sugar spells bad news for our waistlines—and our health.
Although experts aren’t sure of the exact mechanism, sugar has been linked to an increased risk of diabetes, high blood pressure, metabolic syndrome and heart disease. No wonder leading health organizations, such as the AHA, World Health Organization and USDA, have started urging us to slash the added sugar in our diets.
The easiest way to trim your added-sugars intake? Banish all sweetened drinks and any processed foods high in added sugars.
10. Our bodies don’t want us to lose weight for good
If you’ve ever lost weight only to gain it back again, you’ll be glad to know it might not be your willpower that’s the problem.
We now know that when you diet, "your body tries to tell you to eat more by altering production of hormones that control hunger,” says Villacorta, the Eating Free author.
Losing weight impacts your hunger hormones in two ways: it triggers a decrease in hormones that suppress appetite and boosts production of hormones that tell you to eat, like ghrelin.
The good news is you can eat to outsmart those hormones.
“Skipping or delaying meals causes ghrelin, and your appetite, to increase,” says Villacorta. “Eating every three to four hours will help control your appetite.”
At least that’s news we like to hear.
From EatingWell, © Meredith Corporation. All rights reserved. Used with permission.