What to know about vitamin E

Although it may not have the same high profile as some other vitamins like C and D, vitamin E has certainly enjoyed its time in the sun.

As an antioxidant, vitamin E — which is in foods such as seeds, nuts and leafy greens — helps protect us from molecules called free radicals that can damage our cells. The body also uses vitamin E to bolster our immunity, so we can fend off disease.

“Vitamin E plays a role in monocyte production, which are large white blood cells that fight against viruses and harmful bacteria,” explains Julie Stefanski, a registered dietitian for Stefanski Nutrition Services in York, Pennsylvania, and a spokesperson for the Academy of Nutrition and Dietetics.

Given its beneficial properties, vitamin E has long held promise as a possible prevention powerhouse. Initial research even seemed to suggest that taking the vitamin in supplement form could help ward off everything from cancer to heart disease. But other studies have found that taking vitamin E, especially in higher doses, is unhelpful and even potentially harmful — raising the risk of bleeding, stroke and, in some men, prostate cancer.

Not surprisingly, such mixed research results have given way to a more cautious, circumspect approach to vitamin E. Many registered dietitians emphasize getting recommended levels of the vitamin through diet alone and don’t recommend vitamin E supplements for healthy individuals.

[READ: Everything You Need to Know About Vitamin D]

Sources of Vitamin E

“The recommended dietary allowance — the RDA — is 15 milligrams a day, and that’s for both males and females age 14 and over,” notes Hannah Kittrell, a registered dietitian and director of the Mount Sinai PhysioLab, a nutrition and exercise physiology clinic in New York City. The dietary recommendations are slightly higher for women who are pregnant or breastfeeding. Pregnant women need 15 mg per day, and lactating/breastfeeding women require 19 mg daily. Supplements aren’t routinely recommended for women who are pregnant or nursing.

Vitamin E intake recommendations vary for kids, depending on their age. For example, 5 mg is considered adequate for infants 0 to 6 months. Vitamin E is a normal component of breast milk, and infant formula is also commonly enriched with the vitamin. Older children ages 9 to 13 should get 11 mg of vitamin E from food daily.

Registered dietitians roundly agree that vitamin E is safe and beneficial when consumed in food. Great natural sources include:

— Wheat germ oil.

— Sunflower seeds.

— Almonds.

— Hazelnuts.

Spinach.

— Sunflower, safflower and corn oil.

— Peanut butter and other nut butters.

According to Department of Agriculture data, a single tablespoon of wheat germ oil — which is extracted from the germ of wheat grain — is enough to meet the recommended daily allowance for vitamin E.

“While many seeds contain vitamin E, sunflower seeds are clearly the winner,” Kittrell says. Just a handful, or about 2 ounces, has enough vitamin E to meet the 15 mg RDA for vitamin E.

Nuts and nut butters are also a great choice to get more vitamin E. Almonds, hazelnuts, pine nuts and peanuts are all good sources of vitamin E, she says. Vitamin E is also found in a range of other veggies and fruits, from avocado to kiwi.

Overall, eating a well-balanced diet is a safe bet for increasing vitamin E intake. But some registered dietitians and researchers say Western eating patterns that plate lots of processed foods (even though some like cereal are fortified in vitamin E) don’t meet the mark.

“When you talk about ‘What does the American diet look like?’ we’re not eating nuts and seeds and really healthy oils and lots of fruits and vegetables,” says Maret Traber, principal investigator and Ava Helen Pauling Professor at the Linus Pauling Institute at Oregon State University. She’s also a professor in the College of Public Health and Human Sciences.

“What we’re eating is lots of processed food,” says Traber, who runs a laboratory focused on vitamin E research at the Linus Pauling Institute. In addition to governmental funding, like from the National Institutes of Health, her lab has received some support from DSM Nutritional Products in Switzerland, which produces vitamin E supplements.

Most Americans should do more to change their diets so that they get the nutrients, like vitamin E, that they need, Traber says.

[See: How to Make Healthful Dietary Changes Last a Lifetime.]

Vitamin E Supplements

Even though deficiency of vitamin E at a blood-level (called frank deficiency) isn’t common, most people still don’t get the recommended amount of vitamin E in their diet. Yet most don’t have a vitamin E deficiency that causes health problems. “Frank vitamin E deficiency is rare,” and overt symptoms of deficiency symptoms haven’t been found in healthy people who get little vitamin E in their diets, the NIH notes, based on past research. Those with vitamin E deficiency can suffer from vision problems, muscle weakness, a degenerative disease of the nervous system called ataxia and impaired immune function, among other issues.

The naturally occurring vitamin is fat soluble — that is to say, vitamin E is absorbed and stored by fat in our bodies. Certain medical conditions make it harder to absorb fat and, therefore, more likely a person may not absorb enough of the fat-soluble vitamin. People at higher risk for developing a vitamin E deficiency include those with cystic fibrosis, which affects the digestive system, irritable bowel syndromes like Crohn’s disease, pancreatitis and celiac disease, an immune condition that can lead to damage in the small intestine if a person eats gluten (including wheat).

For those who have concerns that they may be vitamin E-deficient, experts advise having a blood test done to check for deficiency. Then discuss with a doctor whether dietary changes and supplementation are warranted, as well as any potential benefits and risks associated with supplementation.

True vitamin E deficiencies are rare, Stefanski says. However, they can occur in these groups of people:

— Individuals who don’t absorb fat very well.

— Premature babies.

— People who follow an extremely low-fat diet.

“It’s more likely that someone would have a mild deficiency that can be corrected by some dietary changes rather than supplementation,” Stefanski says.

Possible Risks of Too Much Vitamin E

Generally speaking, taking a vitamin E supplement if you’re healthy isn’t recommended.

For adults who do take a supplement, it’s advised that you not exceed 1,000 mg — or the equivalent of 1,500 IU, or international units — of vitamin E a day, which is what’s considered the tolerable upper intake level, or UL. That’s the maximum amount a person can take that’s unlikely to cause adverse health effects.

However, some studies indicate there may even be risks associated with taking less vitamin E. For example, while research suggests a vitamin E supplement may help protect against prostate cancer, particularly for men who smoke, other research indicates that taking 400 IU of vitamin E daily could increase prostate cancer. Similarly, some research suggests taking 400 IU of vitamin E daily could increase stroke risk.

It’s worth noting that much of the data comes from studying middle-aged and older patients, so it’s not entirely clear whether other factors, like having chronic disease or taking various supplements (besides just vitamin E), may have contributed to some of the increased risk patients faced. The upper limit remains at 1,000 mg per day.

Still, many registered dietitians urge taking a cautious approach with vitamin E supplementation in general. That means also talking with your doctor about any other supplements or medications you’re taking. For example, taking vitamin E if you’re on a blood thinner, including warfarin (Coumadin), clopidogrel (Plavix) or aspirin, could increase your risk of bleeding.

It’s important to keep in mind that water-soluble vitamins, like vitamin C, aren’t stored in your body. Any excess is excreted in urine. In contrast, vitamin E is fat soluble. This means any excess is stored in the body’s fat tissue and liver, so your body isn’t able to get rid of excess fat-soluble vitamins as quickly or readily.

[Read: Top Pharmacist-Recommended Vitamins and Supplements.]

Side Effects of Too Much Vitamin E

In rare instances, taking more vitamin E than recommended can increase the risk of side effects.

According to the Mayo Clinic, possible side effects include:

— Nausea.

— Diarrhea.

— Intestinal cramps.

— Fatigue.

— Weakness.

— Headache.

— Blurred vision.

— Rash.

— Gonadal dysfunction.

— Increased concentration of creatine in the urine.

If you’re taking vitamin E and experience one or more of these symptoms, stop taking the supplement and call your health care provider.

Research sponsored by the National Eye Institute indicates vitamin E, taken with vitamin C, beta-carotene and zinc, slows the progression of age-related macular degeneration. And, generally speaking, vitamin E is known to protect cells in the eyes (as well as other cells in the body) from damage and therefore could help prevent vision loss. But the precise role this vitamin might play in prevention and management of a range of conditions still isn’t clear.

“Whether vitamin E can prevent cancer, heart disease, dementia, liver disease and stroke still requires further research,” according to the NIH. In the meantime, a safe bet is to improve your diet to get more of the antioxidant — something research has never shown to be harmful.

More from U.S. News

Best Vitamins and Minerals for Older Adults

Foods High in Vitamin K

Summer Superfoods List: From Leeks to Beets

What to Know About Vitamin E originally appeared on usnews.com

Update 03/18/21: This article was previously published and has been updated with new information.

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