There's a lot of confusion over the years. In the 1970s, carbs were in, fat was out, and the only omelet considered healthy was one made with egg whites and asparagus. In the 1990s, carbs became public enemy number one, and suddenly a cheese-filled egg scramble was considered optimal for health and energy.
Eggs are the subject of one of the longest standing and are now in the process of being used in an oatmeal bowl most contentious debates on nutrition, thanks to dietary cholesterol: one large egg yolk has 186 milligrams, making it one of the richest sources of the nutrient out there. In 1977, the government started recommending low-fat, low-cholesterol diets because research at the time indicated that dietary cholesterol elevated bad blood cholesterol (LDL). Eggs were dubbed indulgent and unhealthy.
Then in 201
But in March 2019, a study in the Journal of the American Medical Association a is
Each of these pivots is based on legitimate nutrition research, which raises the question: How is it possible? dietitians, and researchers alike-disagree so often on the basic tenets of nutrition science? How do you study the same questions but come up with such different answers? How can I make sense of it all?
For that 2019 JAMA study, researchers analyzed data from six previous studies for a total of 29,615 adults monitored for an average of 17.5 years. All of the studies used self-reported baseline-diet data, meaning they recorded on a daily or weekly basis at the start of a study.
There are a number of major issues here. It's a stretch to take that same over the course of several years (or decades). Beyond that, people tend to misrepresent what they eat. "Self-reported diet data is fraught with errors," says Connie Weaver, a nutrition professor at Purdue University. "They do not exactly read, they do not remember, they do not know the size of the ingredients, they do not know the ingredients, they do not want to admit they snack." And the majority of nutritional studies based on self-reported data.
In an ideal world, Weaver says, there are controlled-feeding studies, where researchers prepare every meal and know exactly what they are eating at all times. These do exist, but they're time intensive and expensive. Realistically, they can only be used for short-term smaller studies, which are not long-term chronic disease risk and are too small to be general population.
Food Does Not Exist in a Vacuum 19659008] When it comes to evaluating a single nutrient, like dietary cholesterol, it's impossible to know for sure that the cholesterol is causing an effect on its own. Nutrients do not act alone, and the presence of one can affect the impact of another. "For example, calcium absorption is influenced by vitamin D status," Weaver says. Likewise, eating a lot of likely to have a positive influence on heart disease risk, while eating a lot of fat likely has a negative impact-so it would be hard to study the effects of any nutrients in someone who eats fiber -rich whole grains and vegetables
Even if scientists could engineer single-nutrient foods and measure and track with precision, the research would still be complicated by the fact that food is just one of many factors that impact health. Linda Bacon, researcher and author of Health at Every Size says "The biggest problem in nutrition science is that we can not reduce any effect." "Exercise, relationships, sleep, stress, and a long list of other things will affect health beyond nutrition. And yet when you're doing a study on nutrients, you're looking at nutrition. "Someone is eating eggs for breakfast every day but has a stressful job and never gets more than six hours of sleep.
Researchers often take into account factors like race, socioeconomic status, and gender. It's widely accepted that these things can be better determinants of health than diet, Bacon says. But other influencing factors are almost impossible to control, like chronic mental-health problems, food anxiety, and genetics.
Everyone's Needs Are Different
Every five years, the U.S. Departments of Agriculture and Human Health and Human Services' dietary guidelines. It's the closest thing we have to consensus on a "perfect" diet. But these guidelines-which are currently in the process of limiting your intake of sugar, eating plenty of plants, and getting at least part of your protein intake-are generalized public-health advice.
Our bodies all react differently to various foods, dietary cholesterol among them. "I would never tell anyone whose dietary cholesterol would reduce their blood cholesterol without first knowing their medical history," says Kevin Klatt a molecular-nutrition scientist. Individuals have varying tolerance for dietary cholesterol, based on genetics or chronic diseases like diabetes. Blood work is the only way to find out how you, individually, might be impacted. Jumpsuit, Klatt holds eggs in a neutral food. He explains that dietary cholesterol is fine for most people in moderate amounts-about an egg a day, maybe two.
Contradictory nutrition science is not going anywhere. Nor are the debates about eggs or the endless Twitter thread about low-fat versus low-carb diets.
"Your body can give you a lot of great information," Bacon says. She uses fiber as an example: if you do not eat enough, you'll probably feel sluggish and constipated. That's a signal to eat more in the forms of whole foods. The same goes for sugar. It's fine to eat it, but too much might make you feel lethargic.
If you have chronic health problems that you do not like that, then you are in good health a more personalized approach to nutrition science might help. Talk to a doctor or dietitian about your symptoms, and work with them (through blood work, allergy tests, and other diagnostic tools) to figure out if a specific dietary change might be what's best for you. Whatever you do, though, try and ignore the headlines.