Looking for online advice about food and health? A quick Google search brings up plenty to choose from. But don’t assume that the top results are reliable. Here’s the lowdown on a half-dozen popular online myths.
MYTH: Some foods make you more energetic.
“Even though all foods give you energy, some foods contain nutrients that could help increase your energy levels and maintain your alertness and focus throughout the day,” says Healthline.com.
“Here’s a list of 27 foods that have been proven to help promote energy levels.”
To scientists, “energy” means “calories,” not alertness, focus, or how energetic you feel.
Only three of the 27 foods on Healthline’s list—coffee, green tea, and yerba maté—can make you more alert. That’s because they contain caffeine. (Dark chocolate has caffeine, but not as much.)
The proof for the other foods is flimsy, to put it mildly. A few examples:
- Bananas. “They’re an excellent source of complex carbs, potassium, and vitamin B6, all of which can help boost your energy levels,” says Healthline.
That’s it? No study measured alertness, focus, or get-up-and-go when people ate bananas?
A true deficiency of B vitamins or potassium—both rare—can cause fatigue. If you’re not deficient, though, don’t count on extra to boost energy.
- Brown rice. “Thanks to its fiber content, brown rice has a low glycemic index,” says Healthline. “Therefore, it could help regulate blood sugar levels and promote steady energy levels throughout the day.”
Oops.
Brown rice isn’t high in fiber, and it doesn’t necessarily have a low glycemic index (rices vary)...not that either attribute would be proof that brown rice, or any other food, makes you feel more energetic.1
- Yogurt. “The carbs in yogurt are mainly in the form of simple sugars, such as lactose and galactose,” says Healthline. “When broken down, these sugars can provide ready-to-use energy.”
So instead of steady energy levels from complex carbs, people should go for quick, “ready-to-use” energy from sugars? Which is it, Healthline?
Bottom Line: Don’t rely on foods—or supplements—to keep you alert. For a quick pick-me-up, try a bout of exercise.
MYTH: Alcohol prevents heart attacks and strokes.
“If you’re in good shape, moderate drinking makes you 25 percent to 40 percent less likely to have a heart attack, stroke, or hardened arteries,” says WebMD.com in its “Surprising ways alcohol may be good for you” slideshow.
Really?
In many studies that have tracked thousands of people for years, those who have one or two drinks a day do have a lower risk of heart disease and some types of stroke than non-drinkers or heavy drinkers. 2,3
But scientists were never sure if alcohol—or perhaps the healthier lifestyles of moderate drinkers—explained the link...until they studied genes that lead people to drink less.
“In East Asian populations, there are common genetic variants which alter the metabolism of alcohol,” explains Iona Millwood, senior epidemiologist at the University of Oxford.
When you drink alcohol, an enzyme converts it to acetaldehyde. In most people, the acetaldehyde is quickly broken down. But a genetic variant of the enzyme in many people of East Asian descent slows that breakdown, making the acetaldehyde build up. That can cause uncomfortable flushing.
A second variant causes flushing—though less so—by speeding up the conversion of alcohol to acetaldehyde.
“People with these variants have an unpleasant flushing reaction when they drink,” says Millwood. So they drink far less.
When her study in roughly 510,000 people in China used genes to estimate alcohol intake, the results were clear.4
“There were no protective effects of moderate drinking for stroke,” says Millwood.
And since genes, not lifestyle, determined how much the participants drank, the results “are due to alcohol itself,” she adds.
What about heart attacks?
In a similar study—on roughly 262,000 people of European descent—participants who had the second variant consumed 17 percent less alcohol per week and had a 10 percent lower risk of heart disease than those without the variant.5
“For some time, observational studies have suggested that only heavy drinking was detrimental to cardiovascular health, and that moderate consumption may actually be beneficial,” says co-author Michael Holmes, now an associate professor and clinical epidemiologist at Oxford.
In fact, “individuals with a genetic predisposition to consume less alcohol had lower, not higher, odds of developing coronary heart disease,” concluded the study.
Bottom Line: Don’t expect alcohol to protect your health.
MYTH: Omega-6 fats cause inflammation.
[Editor’s note: Since this article was written, MedicalNewsToday.com removed its discussion of omega-6 fats from the article titled “Foods that cause inflammation” on its website.]
“Excessive amounts of omega 6 fatty acids can cause the body to create pro-inflammatory chemicals,” said MedicalNewsToday.com.
“Mayonnaise and salad dressings often have omega 6 fatty acids. Some oils such as corn, safflower, sunflower, and peanut oil can also contain the substance.”
And inflammation, said the website, “is commonly present in people with heart disease and stroke and may have a link to plaques forming in the arteries.”
One source of the claim: omega-6 fats like linoleic acid can be converted to arachidonic acid in the body.
“And arachidonic acid can get converted to prostaglandins, which can set off inflammatory responses,” notes Frank Sacks, professor of cardiovascular disease prevention at the Harvard T.H. Chan School of Public Health.
But hardly any linoleic acid actually gets converted to arachidonic.6
“Although the pathway is there, it’s not active unless there’s a deficiency of omega-6 fats,” says Sacks.
And the body keeps a tight control on arachidonic acid levels.
“When you eat omega-6s, you’ll see an increase in linoleic acid, but you won’t see an increase in arachidonic acid or prostaglandins,” notes Sacks.
That may explain why studies find no increase in inflammatory markers when people are given foods rich in omega-6s.7
And when researchers tracked roughly 69,000 people from 30 studies, those with the highest blood levels of linoleic acid had a lower risk of cardiovascular disease.8 (The analysis was partly funded by mayo and margarine maker Unilever. Both foods are rich in omega-6 fats.)
What’s more, when people were randomly assigned to eat more omega-6 fats instead of saturated fats, they had a lower risk of heart disease.9
“There is no good clinical research that shows adverse effects for omega-6 fats,” says Sacks. “In fact, studies actually show beneficial effects.”
Bottom Line: Researchers still don’t know which foods cause inflammation, but there’s no good evidence that omega-6 fats are to blame.
MYTH: Glucose monitors help you lose weight.
“Glucose is your key to weight loss,” says Signos.com, one of a handful of companies that sell continuous glucose monitors (CGMs).
“This slim wearable device provides continuous glucose monitoring and tracking 24/7.”
Many people with type 1 diabetes—they produce no insulin—wear CGMs to let them know if their blood sugar is too high or low.
But it’s not clear if anyone else needs the devices, especially if weight loss—not controlling blood sugar—is the goal.
(The FDA has approved CGMs only for people with diabetes, but doctors can write an “off label” prescription for anyone. “Rest assured, an independent physician will handle the prescription for you,” says Signos, which charges $99 to $299 a month depending on how many months you sign up for.)
How accurate are CGMs?
Clearly, CGMs are accurate enough to detect dangerously high or low glucose levels.
But “companies are promising to unlock your unique solution for a healthy metabolism by measuring your glucose responses,” says Kevin Hall of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
How well can the devices measure glucose responses in people without diabetes? “We often found very different glucose responses to the same meals when people simultaneously wore two CGMs,” says Hall.
His study tested the Dexcom G4 Platinum and the Abbott Freestyle Libre Pro in 16 volunteers who lived at an NIDDK lab for four weeks.10
Hall’s team also looked at one CGM’s results for the same meal eaten by the same person on two days roughly a week apart. The results were similar but far from identical.
“Are these devices sufficiently accurate and precise?” asks Hall. “I don’t think we know yet.”
Do CGMs help with weight loss?
“Certain foods can cause your glucose to spike beyond your current energy needs,” says Signos. “Your body then converts this excess glucose into fat.”
But there’s no good evidence that people gain more—or lose less—weight if a meal causes a spike in glucose.
“We saw much lower glucose levels on CGMs after meals when we fed people a low-carbohydrate diet as compared to a high-carbohydrate diet,” says Hall.11
“But these differences in CGM glucose didn’t translate to the predicted differences in body fat. In fact, people lost more body fat on the diet that produced the greatest glucose spikes.”
Bottom Line: CGMs can help people with diabetes control their blood sugar. But there’s no good evidence that CGMs help people lose weight.
MYTH: Coconut oil is a superfood.
“The unique combination of fatty acids in coconut oil may have positive effects on your health, such as boosting fat loss, heart health, and brain function,” says the Healthline article “Top 10 evidence-based health benefits of coconut oil.”
But is it good evidence?
- Coconut oil raises good cholesterol? The fats in coconut oil “raise HDL (good) cholesterol in your blood, which may help reduce heart disease risk,” says the article.
But raising HDL may not matter.
“Changes in HDL cholesterol caused by diet or drug treatments can no longer be directly linked to changes in CVD,” says the American Heart Association.9 (CVD is cardiovascular disease.)
- Coconut oil is good for your brain?
“May boost brain function in Alzheimer’s disease,” says the article.
“May” is right. Healthline’s two “trusted sources” refer to “preliminary” studies reporting that when Alzheimer’s patients were given medium-chain triglycerides (MCTs), only some of them did better on cognitive tests.12,13 (In one study, some did worse.) But coconut oil is only about 14 percent MCTs.
“Research is still preliminary, and no evidence suggests that coconut oil itself combats this illness,” says Healthline.
Good to know.
- Coconut oil leads to weight loss? “As some of the fatty acids in coconut oil can reduce appetite and increase fat burning, it may also help you lose weight,” says the article, which cites two studies as evidence.
One was a 2011 pilot study on 20 people that had no control group.14 (Yet Healthline still calls it a “trusted source.”)
In the second study, 40 women given coconut oil lost no more weight than those given soybean oil.15 (The authors claimed that waist size fell by ½ inch in the coconut oil eaters, but didn’t test to see if the difference between groups was statistically significant.)
What Healthline missed: When a 2018 study randomly assigned 91 people to consume roughly 4 tablespoons a day of extra-virgin coconut oil, butter, or olive oil for four weeks, none of the groups lost weight—or waist.16
“Coconut oil is still high in calories, so you should use it sparingly,” says Healthline. Got it.
Bottom Line: Ignore claims that coconut oil is a superfood.
MYTH: Eggs are good for your heart.
“They’re heart healthy,” says the WebMD slideshow “Health Benefits of Eggs.”
“In a recent Chinese study, people who ate about an egg a day were almost 20% less likely than non-egg eaters to develop heart disease,” added WebMD.
But other studies disagree.
“Combining data from nearly 30,000 people in six U.S. studies, we found a 6 percent higher risk of cardiovascular disease for each half egg eaten per day,” says Linda Van Horn, professor of preventive medicine at the Northwestern University Feinberg School of Medicine.17
But those “observational” studies can’t be sure that it isn’t something else about egg eaters that affects their risk.
“More convincing” are feeding studies that serve people diets that are higher or lower in eggs, said a 2020 American Heart Association advisory on high-cholesterol foods like egg yolks.18 (Van Horn served on the AHA panel that wrote the advisory.)
“Eggs can increase blood cholesterol levels,” says Van Horn. “So it’s best not to assume that you can eat as many as you want.”
The AHA’s advice:
- Healthy people can eat up to one egg a day.
- Vegetarians can eat more than one egg a day since they’re not getting cholesterol from meat, poultry, or seafood.
- Older people with normal cholesterol levels can eat up to two eggs a day if they eat a healthy diet overall.
- People with high LDL (“bad”) cholesterol should “be cautious” about eating eggs, especially if they have diabetes or are at risk for heart failure.
“If you have elevated cholesterol, if you have diabetes, or if you have over-weight or obesity, you’re already at higher risk for developing cardiovascular disease,” cautions Van Horn.
And that’s not just a few of us, she notes.
“We have a population that has increasing rates of obesity. And that raises the risk of cancer, cardiovascular disease, type 2 diabetes, you name it.”
Bottom Line: Stick with the AHA’s advice on eating eggs...and its advice to eat a diet rich in fruits and vegetables, with beans, whole grains, seafood, poultry, low-fat or fat-free dairy, nuts, and oils.
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2JAMA 289: 579, 2003.
3BMJ 2011. doi:10.1136/bmj.d671.
4Lancet 393: 1831, 2019.
5BMJ 2014. doi:10.1136/bmj.g4164.
6J. Lipid Res. 46: 269, 2005.
7J. Clin. Endocrinol. Metab. 104: 6207, 2019.
8Circulation 139: 2422, 2019.
9Circulation 136: e1, 2017.
10Am. J. Clin. Nutr. 112: 1114, 2020.
11Nat. Med. 27: 344, 2021.
12Neurobiol. Aging 25: 311, 2004.
13Ann. N Y Acad. Sci. 1367: 12, 2016.
14ISRN Pharmacol. 2011. doi:10.5402/2011/949686.
15Lipids 44: 593, 2009.
16BMJ Open 8: e020167, 2018.
17JAMA 321: 1081, 2019.
18Circulation 141: e39, 2020.