Despite the fact that we’re more aware of our nutritional needs than ever before, nutrient deficiencies are a very real problem—even in developed nations like the United States. In fact, an estimated 92 percent of the U.S. population is deficient in at least one vitamin or mineral, according to CDC research.

Several potential factors likely contribute, including our increased consumption of processed foods, says The Vitamin Shoppe nutritionist Rebekah Blakely, R.D.N. “The recommended amounts of necessary nutrients are mainly found in fruits and vegetables,” she explains. “And, even when we do eat produce, the soil in which we grow food has been depleted over time in some areas from modern agricultural practices.”

Another factor: “More and more people are eating restricted diets, for various reasons like health, food allergies, and personal preference, which often means eliminating food groups rich in key nutrients,” Blakely says.

Read More: 3 Ways Restrictive Diets Can Mess With Women’s Hormones

Additionally, there’s a high prevalence of medical conditions (and associated medications) that affect nutrient absorption and needs. One of those medial conditions: chronic stress. Research published in the journal Advanced Nutrition shows stress can deplete the body’s micronutrient concentrations. This is often a double-whammy, since many Americans take medications to combat rising stress levels that also impact their nutrient absorption, adds Dr. Josh Axe, D.N.M., C.N.S., D.C., founder of Ancient Nutrition and member of The Vitamin Shoppe Wellness Council.

Luckily, there’s plenty you can do to correct your own nutrient deficiencies and support more optimal health. If you’re wondering what nutrients you might be low in, here are the most common nutritional deficiencies in the U.S.

Vitamin D

Exposure to sunlight is our body’s primary way of getting vitamin D, which is why it often goes by the nickname “the sunshine vitamin.” Given the fact that the majority of us spend more time indoors than ever before, it’s no surprise that an estimated 35 percent of adults in the U.S. are deficient in the nutrient, per a study published in The Journal of Steroid Biochemistry and Molecular Biology.

“Vitamin D plays a critical role in several body functions, including calcium absorption, immune system function, cardiovascular health, and mood balance,” says Axe. “Since an estimated 90 to 95 percent of most people’s vitamin D comes from casual sunlight exposure, it’s important to try to get at least 10 to 15 minutes of direct sunlight, without sunscreen, daily.”

Read More: 7 Signs You Have A Vitamin D Deficiency

When you can’t get in the sun, for whatever reason, Axe recommends reaching for cod liver oil, wild-caught salmon, pastured eggs, fortified dairy products, fortified nut milks, and mushrooms exposed to UV light—all of which can help support vitamin D levels. You can also take 1,000 to 2,000 IU of a high-quality vitamin D3 supplement per day, he suggests.

Vitamin B12

Also known as cobalamin, this water-soluble vitamin plays a role in producing red blood cells and supporting brain function. However, up to 15 percent of the general population is deficient in it, per the National Institutes of Health.

“Because vitamin B12 is primarily found in meat, dairy, and eggs, those following a plant-based diet are especially at risk for deficiency,” says The Vitamin Shoppe nutritionist Brittany Michels, R.D.N. “Same goes for the elderly, who start losing the ability to absorb vitamin B12 in their gut through the aging process.” Since vitamin B12 influences mental health, nervous system function, and red blood cell formation, symptoms of deficiency tend to include low mood, a prickling sensation in your extremities, and/or fatigue from poor oxygen transport.

In addition to eating foods rich in vitamin B12, such as wild-caught salmon, grass-fed beef, eggs, cottage cheese, and nutritional yeast, Axe recommends taking a probiotic supplement, which can help the body absorb the nutrient properly. “If you choose to take a B12 supplement, aim for 200 milligrams twice daily, taken in combination with 25 billion cultures from a probiotic supplement,” he says.

Vitamin B6

Our bodies can’t produce vitamin B6 on their own. Fortunately, though, it’s naturally present in a variety of different foods, such as pork, poultry, bananas, chickpeas, tuna, salmon, and beef, per the NIH.

“Vitamin B6 aids in melatonin, serotonin, and dopamine production, so it’s essential for mood regulation and sleep,” says Michels. ‘It also helps decrease levels of homocysteine, an amino acid that, in high levels, can influence heart, brain, and eye health.”

Since it’s so abundant in foods, stress and inflammation are the more likely causes of low B6 levels, Michels adds.

If you’re not getting enough vitamin B6 through your diet or are concerned that stress could be impacting your levels, Michels recommends taking a multivitamin or a B-complex that includes B6.

Iron

Iron deficiency is a problem worldwide, not just in the United States. In fact, an estimated 10 million Americans are deficient, including five million who suffer from iron deficiency anemia, per research published in Cold Spring Harbor Perspectives in Medicine.

A result of their monthly menstrual cycles and higher iron needs during pregnancy, women are more likely to be deficient than men, notes Blakely. “People with chronic bleeding issues (like an ulcer) are also more prone to anemia, as are those who do vigorous exercise due to more rapid breakdown of red blood cells,” she adds.

Those following a vegan and vegetarian diet may also be prone to iron deficiency, since the foods highest in iron are animal proteins. If you are plant-based, Blakely stresses the importance of intentionally incorporating high-iron foods (such as beans, lentils, soy, peas, and dark leafy greens) and pairing them with foods high in vitamin C to increase absorption.

“A daily multivitamin can supply some or all of your iron needs, which are eight milligrams for men, 18 milligrams for women, and 27 milligrams for pregnant women,” she adds.

Iodine

According to the CDC, Americans’ iodine levels have been decreasing since before 200. Blakely believes this is most likely due to changes in food production. “Many processed foods and restaurants no longer use iodized salt,” she says. “This has been a primary source of iodine in many people’s diets since it was introduced in the 1920s to help eliminate iodine deficiencies.”

If you don’t use iodized salt in your cooking at home or don’t consume high-iodine foods—such as seafood, milk, yogurt, and eggs—regularly, Blakely recommends a multivitamin that contains it.

Read More: Could You Have A Thyroid Issue?

Men and women need 150 micrograms daily, while pregnant women need 220. “Be careful not to over-supplement with iodine, however, as too much can also cause problems, especially for those who already have thyroid issues,” she adds. When in doubt, stick to your multi and check in with your doctor or a dietitian.

Omega-3s

Finally, you’ve probably heard about these good-for-you fats. Omega-3s play a key role in heart and brain health, which are incredibly important in aiding our overall health and longevity, Michels says.

Despite the importance of omega-3s, though, few Americans eat the two servings of fatty fish per week necessary for adequate intake. Plus, those with certain health conditions who work out at high intensities and consume a lot of sugar, alcohol, and/or processed foods may have higher needs.

Michels recommends consuming foods high in omega-3s, such as nuts, seeds, eggs, and fish like salmon and sardines. Or, supplement with 1.1 grams daily.