Zoe Saldana has Hashimoto’s thyroiditis. What is it?

Zoe Saldana attends the premiere of Paramount Pictures' "Star Trek Beyond" at Embarcadero Marina Park South on July 20, 2016 in San Diego, California. Kevin Winter/Getty Images/AFP

Last week, Star Trek: Beyond and Guardians of the Galaxy star Zoe Saldana announced that she has Hashimoto’s thyroiditis.

Also known as autoimmune thyroiditis, Hashimoto's thyroiditis is an autoimmune disease that affects the thyroid, a small gland in the neck that helps control the body's metabolism.

The first symptom of the disease, says the US Department of Health and Human Services (HHS), is usually an enlarged thyroid, or goiter.

The HHS adds that the disease is also the most common cause of an underactive thyroid, or hypothyroidism, in the US, though not everyone with Hashimoto's disease develops this condition.

An underactive thyroid causes many of the body's functions to slow down. Symptoms of hypothyroidism, reports the American Thyroid Association, "include extreme fatigue, depression, forgetfulness, and some weight gain." The US Health Department also adds joint and muscle pain, constipation, irregular periods and problems getting pregnant to the list.

Hashimoto's Disease is believed to be caused by any of several factors that include genetics, too much iodine, and pregnancy. Women are about seven times more likely to have the disease than men, says the HHS.

Many people with thyroid problems treat their disease by changing their diet, pointing to gluten (proteins found in common grains such as wheat) as making the problem worse.

Saldana, who says that both her mother and her sister also suffer from the disease, has shifted to a gluten-and dairy-free diet as a result of her diagnosis.

“Your body doesn’t have the energy it needs to filter toxins, causing it to believe that it has an infection, so it’s always inflamed,” Saldana told Net-a-Porter magazine. “You create antibodies that attack your glands, so you have to eat clean.” — BM, GMA News