Vitamins A and E: Why they can do more harm than good

There are many important supplements that benefit people with specific disabilities or certain health conditions. but research shows, and experts say, that some synthetic vitamins can do more harm than good.

“Everyone is always looking for that magic pill that will give them great health, but nutritional supplements just aren’t because the benefits often don’t outweigh the risks,” says JoAnn Manson, chief of preventive medicine at Brigham and Women’s Hospital. Boston, Massachusetts.

That’s not to say that certain groups of people don’t need certain nutrient supplements at certain points in their lives; it’s just that most people don’t need to supplement with every vitamin they can think of.

“In general, I don’t recommend taking vitamin supplements unless there’s a specific reason to do so,” says Walter Willett, professor of epidemiology and nutrition at Harvard’s TH Chan School of Public Health.

Such advice is especially true for fat-soluble vitamins.

Water soluble vs. fat soluble

Water-soluble and fat-soluble nutrients are absorbed differently in the body.

Water-soluble vitamins, which include vitamin C and all eight B vitamins, are rapidly dissolved, processed and metabolized in the body and are not stored for later use.

“Excess amounts of water-soluble vitamins are excreted in the urine,” explains Alice Lichtenstein, director of the Cardiovascular Nutrition Team at Tufts University’s Jean Mayer US Center for Human Nutrition Research.

On the other hand, the fat-soluble nutrients, vitamins A, D, E, and K, are stored in the liver and adipose (adipose) tissue throughout the body for later use. While this helps build up vitamin D during the summer sun to compensate for less exposure to sunlight in the winter months, it also means that these vitamins can build up to potentially toxic levels.

That’s why Tolerel Upper Intake Level (UL) safety guidelines are provided by the National Academies of Sciences, Engineering, and Medicine to indicate the maximum amount of certain vitamins that can be safely consumed without adverse health effects.

“Fat-soluble vitamins tend to have a lower UL compared to water-soluble vitamins, which emphasizes the need for caution when using them,” explains Jen Messer, registered dietitian and president-elect of the New Hampshire Academy of Nutrition and Dietetics.

Among the four fat-soluble vitamins, experts say vitamins A and E require more caution than the others.

Vitamin A concerns

Vitamin A is important for vision, growth, reproduction and immune health. When consumed through natural food sources such as beef liver, sweet potatoes, spinach, carrots, or pumpkin pie in the recommended amounts of 900 mcg per day for adult men and 700 micrograms per day for adult women, vitamin A is considered safe and important.

The upper limit of the maximum daily intake of vitamin A has been set at 3000 mcg, although it is important to note that such intakes include consumption or absorption of vitamin A. all sources of vitamin A, including foods, supplements, and creams/lotions that contain retinol. (For context, consider that 3 ounces of roast beef liver contains 6,582 micrograms of the vitamin.)

Exceeding the UL is dangerous, and “one large dose of it can contribute to toxicity,” explains Yufang Lin, MD, a primary care physician at the Cleveland Clinic’s Center for Integrative Medicine. Such toxicity can cause problems such as joint pain, liver damage and birth defects.

“Vitamin A is necessary for normal fetal development, but too much of it can harm both the mother and the developing fetus, raising the risk of birth defects in the eyes, heart, organs and central nervous system,” says Messer. .

Even in moderate amounts and outside of pregnancy, “vitamin A supplements are associated with increased risk of skin irritation and bone fractures,” says Manson.

Research published earlier this year suggests that vitamin A toxicity can also occur from topical vitamin A (retinol), which is used to treat acne and psoriasis.

There have even been problems with including vitamin A in multivitamins. “At one point there was concern about the amount of vitamin A in multivitamin supplements and bone loss in older women,” Lichtenstein explains. He says that’s why some multivitamin brands now only include vitamin A as an ingredient in the form of beta-carotene. (Studies show that beta-carotene is converted to vitamin A in the body, but carries fewer risks than other forms.)

Furthermore, although some studies suggest that vitamin A from a balanced diet may reduce the risk of certain types of cancer; The NIH Office of Dietary Supplements states that its supplement form can growth the risk of certain cancers because of vitamin A’s role in regulating cell growth and differentiation.

“Long-term, high-dose vitamin A intake can also lead to liver disease, elevated blood lipids, bone and muscle pain, and vision problems,” says Kate Zeratsky, a registered dietitian nutritionist at the Mayo Clinic in Rochester, MN. “Early signs of vitamin A toxicity can include dry skin, nausea, headache, fatigue, enlarged liver and hair loss, among other possible symptoms.”

Vitamin E concerns

Vitamin E is an even more controversial fat-soluble supplement.

When it occurs naturally in foods such as wheat germ oil, avocados, fish, seeds, and nuts such as almonds, hazelnuts, and peanuts, vitamin E is a powerful antioxidant that protects human cells from free radical damage and improves skin health. and eye health.

But the nutrition department at Harvard’s Chan School of Public Health notes that the safety profile of its synthetic form is a matter of controversy among scientists; harmful and even increases the risk of death.”

One of the points of controversy and confusion surrounding vitamin E is that the nutrient comes in many forms, some of which are more studied than others.

“Vitamin E has eight naturally occurring chemical forms, while most vitamin E supplements are synthetic alpha-tocopherol,” Lin explains. It is this form of alpha-tocopherol that carries more risks than other forms of vitamin E. “This is an argument that it is better to eat foods rich in vitamin E than to take synthetic supplements.”

Zeratsky agrees. “I think there is a need to better understand how the different forms of vitamin E work and interact in our bodies,” he says.

There is also some confusion about how much vitamin E can be safely consumed. The recommended dietary allowance (RDA) for vitamin E is 15 milligrams for both adult men and adult women, but the upper limit of daily intake is 1,000 milligrams. The NIH Office of Dietary Supplements states that “taking vitamin E supplements even below these upper limits may cause harm.”

Indeed, clinical research shows that taking just 268 milligrams of vitamin E per day can increase men’s risk of prostate cancer by 17 percent. The form used in supplements has also been linked to lung cancer.

“And you don’t have to reach toxic levels to experience the downsides,” Manson adds. “Randomized trials of vitamin E have documented problems even in moderate amounts.”

Higher doses of vitamin E supplements can also interfere with blood clotting, which can cause bleeding, says Jessica Rose, MD, a bariatric dietitian at Upper Chesapeake Health University in Maryland.

Because of these and other issues, research published by the American Heart Association suggests that supplemental vitamin E is no longer recommended at the higher levels needed to protect against chronic diseases such as cancer, arthritis, and cataracts.

“Ultimately, it’s about weighing the balance between potential risks and benefits,” explains Messer.

Lack of regulation of food additives

Another area of ​​concern for experts that affects both water- and fat-soluble vitamins is that nutritional supplements are not regulated by the US Food and Drug Administration (FDA) using the same standards as foods and drugs.

This can lead to false claims and even labels that misrepresent the ingredients in every supplement bottle. “According to a recent independent analysis of 57 dietary supplements, 84 percent did not contain the required amount of ingredients, while 40 percent of supplements did not contain any of the claimed ingredients,” says Messer. “Furthermore, 12 percent of the supplements contained undeclared ingredients, which are prohibited by the FDA.”

So the onus is on consumers to choose reputable supplement brands and buy products that have been tested and labeled by approved third parties. “And be very wary of any supplement that claims it can cure a disease, because supplements are not allowed to make such claims,” ​​Lynn says.

It’s also important to check daily dosage recommendations and upper limits for dietary supplements and make sure that one supplement you take won’t interfere with another. “Talk to your doctor or a nutritionist to help determine the specific nutrients you need,” Rose suggests.

“It’s a common misconception that vitamin supplements are good for everyone,” says Messer. “They may be beneficial for certain individuals in certain situations, but they are not universally necessary, can be expensive, and are not entirely risk-free.”