The Effect of Vitamin E on the Thyroid

Your thyroid is a small, butterfly-shaped gland that sits at the front of your throat. It uses the mineral iodine (obtained through the diet) and the amino acid tyrosine (which your body makes on its own) to produce two primary thyroid hormones. These are known as triiodothyronine (T3) and thyroxine (T4). These hormones influence the rate at which your body uses energy, also called your metabolic rate.

If your thyroid doesn’t make enough of these hormones, you have a condition called hypothyroidism, also known as an underactive thyroid. If it makes too much, you have hyperthyroidism, or an overactive thyroid.

The effects of dietary vitamin E or vitamin E supplementation on the thyroid have not been extensively studied in people. But some animal studies suggest a possible role for vitamin E in treating certain thyroid problems.

Function of Vitamin E in the Body

Vitamin E is a fat-soluble nutrient that has antioxidant effects in your body. Antioxidants protect your cells from the potential damage of unstable molecules known as free radicals. Vitamin E is also involved in immune function and cardiovascular health, according to the National Institutes of Health (NIH) Office of Dietary Supplements.

Food sources of vitamin E include nuts, seeds, vegetable oils, green leafy vegetables, and fortified cereals. Vitamin E deficiency is rare. But people who have problems absorbing fat in the digestive system may need supplemental vitamin E.

Lower Rates of Subclinical Hypothyroidism

One study that did involve people suggested that a higher intake of dietary vitamin E is linked with lower prevalence rates of subclinical hypothyroidism and autoimmune thyroiditis among males. No significant link was observed among females.

Subclinical hypothyroidism occurs when thyroid-stimulating hormone (TSH) levels are elevated but levels of thyroxine (T4) are normal. It may or may not cause symptoms, and it may or may not require treatment, according to Cleveland Clinic.

In autoimmune thyroiditis, or Hashimoto’s disease, the immune system attacks healthy cells in the thyroid, usually leading to hypothyroidism, according to Mayo Clinic.

The study used data from the National Health and Nutrition Examination Survey database and included 7,773 adults in its analysis.

Preserved Cell Function in Hyperthyroidism

An animal study looked at the capacity of vitamin E supplementation to protect mitochondria from oxidative damage in hyperthyroidism.

Mitochondria are often referred to as the “powerhouses” of the cell. That’s because they generate energy in the cells, in addition to contributing to many processes central to cellular function and dysfunction, according to Britannica. Mitochondria both produce and are targeted by reactive oxygen species, a type of free radical.

The study found that vitamin E supplementation to hyperthyroid animals limits the thyroid hormone–induced increases in mitochondrial reactive oxygen species and oxidative damage. It also, through other mechanisms, preserves cell function.

Some older, smaller studies suggest that people with hyperthyroidism have lower levels of vitamin E than the general population. This could help to explain why vitamin E supplementation may be beneficial in those who have the condition.

Dosage and Precautions

If you’re considering taking vitamin E supplements for any reason, including the health of your thyroid, discuss it with your doctor first.

According to Cleveland Clinic, vitamin E supplements can increase your bleeding risk if you are taking blood thinners — medications that stop or slow the formation of blood clots. The supplements can also interfere with statins and niacin (taken to improve cholesterol levels) and with some chemotherapy agents (used to treat cancer).

The recommended daily amount of vitamin E for adults is 15 milligrams (mg) a day, or about 22 international units (IU). Most vitamin E supplements contain much more than that. To avoid vitamin E toxicity, adults are cautioned not to take more than 1,000 mg per day, 1,500 IU of d-alpha-tocopherol (natural vitamin E) per day, or 1,100 IU of dl-alpha-tocopherol (synthetic vitamin E) per day.