Concerns about nutrient deficiencies have become increasingly common with health influencers frequently promoting supplements, powders and injections that promise to do everything from boosting wellness to preventing nutritional shortfalls. While some nutrients, such as fiber, vitamin D and certain minerals can be difficult for Americans to get enough of, true vitamin deficiencies remain relatively uncommon among healthy adults.

That’s especially true of vitamin K, a nutrient that has recently gained a lot more attention online. “Most people get enough vitamin K from food, body stores and gut bacteria synthesis,” says Jen Messer, a researcher, registered dietitian and president of the New Hampshire Academy of Nutrition and Dietetics.

Even so, some people are looking to increase their vitamin K intake in hopes of supporting bone and heart health and overall wellness. While many individuals focus on eating more vitamin K-rich foods such as leafy greens, others turn to supplements, and, increasingly, vitamin K injections.

Here’s what to know about this important nutrient, why it matters and whether vitamin K shots are actually safe or effective.

What is vitamin K? Why is vitamin K important?  

Vitamin K is a fat-soluble vitamin that plays an essential role in blood clotting and bone health, says Messer. Without enough of it, she says, “even small cuts could bleed longer than normal.” The nutrient also helps regulate how calcium is used in the body, directing it toward bones and teeth while also helping limit calcium buildup in blood vessels and other soft tissues.

There are two main forms of vitamin K. Vitamin K1 is found primarily in leafy green vegetables, while vitamin K2 is present in certain animal products and fermented foods and is also produced by beneficial bacteria in the gut.

Because vitamin K is fat-soluble, it is absorbed alongside dietary fat and stored in the body’s tissues. That means “the body doesn’t flush excess vitamin K out right away the way it does water-soluble vitamins,” explains Yasi Ansari, a registered dietitian nutritionist and Los Angeles-based certified sports dietetics specialist. This is one reason deficiency is relatively uncommon among healthy adults.

When vitamin K deficiency does occur, Ansari says it is usually linked to conditions that impair fat absorption, such as certain digestive disorders, liver disease or prolonged use of certain medications, including antibiotics.

Symptoms of vitamin K deficiency include easy bruising, nosebleeds, bleeding gums, delayed blood clotting and, in severe cases, weakened bones or internal bleeding.

What are fat-soluble vitamins? If you take daily vitamins you should know the difference

What are vitamin K shots?

Vitamin K shots are injections that deliver vitamin K directly into the body. “They are usually administered in the thigh muscle and go straight into the bloodstream and are fast and long-lasting,” says Messer.

Vitamin K shots are unlike dietary vitamin K or oral supplements, which must be swallowed and then absorbed through the body’s digestive process. For that reason, vitamin K shots are generally reserved for specific medical situations such as when deficiency needs to be corrected quickly.

The most common use of vitamin K shots is in newborns. “Newborns are more prone to vitamin K deficiency because they are not yet able to produce vitamin K through their intestines and don’t usually get enough vitamin K during pregnancy,” explains Ansari. As a result, they face an increased risk of a rare but potentially life-threatening condition known as vitamin K deficiency bleeding (VKDB). To prevent this, the American Academy of Pediatrics recommends a single vitamin K injection shortly after birth.

Adults may also receive vitamin K injections when a healthcare provider determines they have a significant deficiency or when rapid vitamin K replacement is medically necessary.

What is vitamin K? Benefits of vitamin K how to know if you’re getting your daily dose.

Are vitamin K shots safe?

When administered under medical supervision, “vitamin K injections are generally considered safe and effective,” says Ansari. Serious side effects are uncommon, but the most common reactions are temporary soreness, redness or swelling at the injection site.

As vitamin K injections are most often recommended for babies, some parents have expressed concerns about a possible link between newborn vitamin K shots and childhood cancer because of a 1990 study that first raised the question. “But many large follow-up studies have found no evidence of this connection,” says Messer.

Vitamin K injections may also be used to counteract the effects of certain blood-thinning medications that interfere with vitamin K activity, and are also sometimes suggested for people with certain medical conditions and diagnosed deficiencies.

Beyond such medically established uses, some wellness influencers also promote vitamin K shots as a way to support detoxification, longevity or anti-aging. However, there is little evidence to support these claims, and vitamin K injections are not recommended by credible medical organizations for such purposes.

“The adequate intake for vitamin K is 120 micrograms per day for adult men and 90 micrograms per day for adult women,” says Messer. She explains that most adults can meet such needs through a balanced diet that includes foods such as spinach, kale, broccoli, Brussels sprouts and a variety of other foods, making routine supplementation unnecessary for most people.

But if you are considering vitamin K supplementation – and especially if you’re considering vitamin K injections – Messer recommends speaking with your healthcare provider first.

This article originally appeared on USA TODAY: What are vitamin K shots? Benefits, risks explained.