Key takeaways:
Vitamin D is the number one vitamin deficiency in the U.S. A simple blood test can determine your vitamin D level.
Many adults are also not getting enough potassium, calcium, iron, and iodine from their diets.
If you have a vitamin deficiency, it doesn’t necessarily mean you need a supplement. You can often get what you need from the right mix of fruits, vegetables, grains, dairy, and protein foods.
If you find it difficult to eat a balanced diet, you are not alone. In fact, most people in the U.S. find doing taxes, exercising regularly, and cooking Thanksgiving dinner easier than eating healthy. But eating a variety of whole foods every day can help prevent nutritional deficiencies. So, here we talk through the most common nutrient deficiencies and actionable tips to get more of them in your diet.
1. Potassium
Potassium is an essential mineral for your health — but most people are not getting enough of it. Potassium acts as an electrolyte that helps with fluid balance, heart health, and muscle function. It’s important to get enough potassium from your diet as it helps to lower blood pressure and can balance out the sodium in your diet.
How common is potassium deficiency?
A whopping 98% of people in the U.S. aren’t getting enough potassium.
What are the symptoms?
Low potassium can increase your risk of high blood pressure, kidney stones, and osteoporosis.
But serious potassium deficiency is somewhat rare. Hypokalemia is the medical term for low blood potassium. And it’s usually not caused by not getting enough potassium in your diet. It’s often caused by losses from the kidneys or the gastrointestinal (GI) tract.
How do you know if you have potassium deficiency?
In most healthy adults, a blood test for potassium will rarely be out of range as your body closely regulates potassium levels.
People at risk of potassium deficiency include those with:
Chronic diarrhea
Any condition that causes repeated vomiting
Diuretic use
High blood sugar
Chronic kidney disease
Low magnesium intake
How to get more potassium in your diet?
Most adults should get 4,700 mg of potassium per day. Potassium is found in fruits, vegetables, cow’s milk, yogurt, meat, some fish, beans, and peas.
Potassium-rich foods include:
Dried apricots
Lentils
Acorn squash
Baked potatoes
Kidney beans
Bananas
Cow’s milk
It’s important to note that supplements contain very little potassium because getting too much potassium can also be unsafe. It’s important to talk with your healthcare team before taking any supplement with potassium. This is especially true for anyone with kidney conditions.
2. Vitamin D
Vitamin D is a fat-soluble vitamin that primarily comes from sun exposure and a few foods. It helps with bone health, energy, immunity, blood sugar management, and mood. Because vitamin D has such a wide range of health benefits, 6 in 10 adults are trying to get more of it.
How common is vitamin D deficiency?
Nine in 10 adults in the U.S. don’t get enough vitamin D in their diets.
What are the symptoms?
Oftentimes people don’t notice the symptoms of vitamin D deficiency. That’s because many of the symptoms are things people feel all the time, or can happen for a number of different reasons. These symptoms include:
Hair loss
Weakness
Memory or concentration issues
Changes in mood
Vitamin D deficiency can also lead to osteoporosis, which doesn’t cause any symptoms until it leads to a bone fracture.
How do you know if you have vitamin D deficiency?
If you’re concerned about a possible vitamin D deficiency, talk with a healthcare professional about getting a blood test. A normal range is anything between 30 ng/mL and 100 ng/mL.
People at higher risk for vitamin D deficiency include:
Anyone with limited sun exposure, like those who live in northern climates
Older adults, who don’t make as much vitamin D from sunlight
People with darker skin
Those who don’t consume milk, or those who follow a vegan diet
Breastfed infants
How to get more vitamin D in your diet?
Most adults should get at least 600 IU of vitamin D per day. But it can be difficult to get enough vitamin D from your diet because not many foods are high in vitamin D. This is why many people choose to take a vitamin D supplement.
Foods high in vitamin D include:
Cow’s milk (most yogurts and cheeses don’t contain high amounts of vitamin D)
Plant-based milk alternatives that are fortified with vitamin D
Fatty fish
Egg yolks
Mushrooms
Beef liver
3. Calcium
Some of the nutrients on this list can fly below people’s radar — but calcium isn’t one of them. Most people in the U.S. know the importance of calcium for bone health. That’s why 6 in 10 people are trying to incorporate more calcium in their diets. Getting enough calcium is important for more than just bones. It’s also important for teeth, muscle and nerve function, blood vessel relaxation, and hormone secretion.
How common is calcium deficiency?
One in 3 men and 6 in 10 women don’t get enough calcium in their diets.
What are the symptoms?
Early calcium deficiency will likely have no symptoms. Longer periods of calcium deficiency — also called hypocalcemia — may cause:
Tingling in hands and feet
Muscle spasms
Irritable or low mood
Fatigue
Coarse hair, brittle nails, or dry skin
And like vitamin D deficiency, calcium deficiency can lead to osteoporosis over time.
How do you know if you have calcium deficiency?
A blood test for calcium may not show the true picture of calcium status in your body. Roughly 98% of calcium in your body is stored in your bones and teeth. Because of calcium’s important role in regulating heart rhythm, your body will take calcium from your bones to make sure you have enough in your blood. This means your body may be taking calcium from your bones without you knowing it.
People at risk of calcium deficiency include those who:
Are postmenopausal
Avoid dairy products
Have low levels of parathyroid hormone
Have vitamin deficiency
Take certain medications, like diuretics and tamoxifen
How to get more calcium in your diet?
Most adults should get at least 1,000 mg of calcium per day. Adults over the age of 50 years should aim for 1,500 mg per day. Calcium-rich foods include:
Yogurt
Cow’s milk
Cheese and cottage cheese
Soy milk and other calcium-fortified plant-based beverages
Fish without the bones removed
Cooked spinach, turnip greens, or kale
4. Iron
Iron is an important mineral that helps your body make red blood cells. These are the cells that carry oxygen throughout your body. It also helps make hormones and protect brain health, and plays an important role in child development and growth. So it’s no surprise that close to half of people in the U.S. try to include iron in their diets.
How common is iron deficiency?
Many people have iron deficiency, but they don’t know it. That’s because iron deficiency is often not diagnosed until it starts to affect blood counts. (This is called iron-deficiency anemia.) Up to 1 in 3 adults have low iron stores.
What are the symptoms?
Like with vitamin D deficiency, the symptoms of iron deficiency can be hard to recognize. They can be vague, and/or similar to symptoms people feel for many different reasons. These include:
Fatigue and weakness
Restless legs
Hair loss
Headaches
Difficulty concentrating
Increased infections from low immune function
How do you know if you have iron deficiency?
You need a blood test to know if you are iron deficient. But this is not as simple as measuring your iron levels, like you can do with vitamin D. In fact, many healthcare professionals don’t even know that the best way to know if your iron stores are low is to check a ferritin level in the blood.
Causes of iron deficiency include inadequate intake from food, decreased iron absorption, and blood loss. People at risk of iron deficiency include:
Breastfed babies between 7 and 12 months of age
Pregnant women
Women of reproductive age who menstruate
People with gastrointestinal issues that affect nutrient absorption
People with cancer
People who donate blood
People with heart failure
How to get more iron in your diet?
The amount of iron you need each day depends on a few factors. Here’s a quick guide:
Men: 8 mg
Women: 18 mg
Women who are pregnant: 27 mg
Women who are lactating: 10 mg
Men and women older than 51 years: 8 mg
The highest quality iron comes from meat and seafood sources. Some iron can be found in nuts, beans, vegetables, and fortified grains. Food sources of iron include:
Lean meat including beef
Whole-grain breakfast cereals
Fortified infant cereals
Boiled lentils
Boiled spinach
Tofu
Kidney beans
Infant formula is fortified with iron, but breastmilk is a low source of iron.
5. Iodine
Iodine is crucial for healthy thyroid function. This is why it was added to salt in the 1920s — to prevent widespread iodine deficiency. Even mild to moderate iodine deficiency during pregnancy can affect fetal development and reduce a baby’s future intelligence quotient (IQ).
How common is iodine deficiency?
Most people in the U.S. are getting enough iodine. But intakes are declining because of the way food processing has changed over the years. Most people had a 50% reduction in iodine levels between the 1970s and 1990s.
What are the symptoms?
Iodine deficiency impacts your body by reducing thyroid function. When your thyroid function gets low, it can lead to hypothyroidism. Symptoms of hypothyroidism include:
Fatigue
Depression
Dry skin and hair loss
Digestive problems
Weight gain
Irregular periods
An enlarged thyroid gland in the neck, called a goiter
How do you know if you have iodine deficiency?
Testing for iodine status is done with urine samples. But urinary iodine levels change rapidly and may not be an accurate way to know someone’s overall iodine status.
Many times, iodine deficiency is assessed through lab tests for thyroid function. But there are additional tests that a healthcare professional can check to look for iodine deficiency.
Talk with your healthcare team if you’re concerned about your iodine intake or thyroid health. Because of their higher nutrient needs, pregnant and lactating women are at risk of iodine deficiency. People who avoid dairy products or don’t use iodized salt are also at risk of iodine deficiency.
How to get more iodine in your diet?
Most adults need 150 mcg per day. Women who are pregnant need 220 mcg per day, and women who are lactating need 290 mcg.
It’s important to note that processed foods with salt don’t use iodized salt. Good sources of iodine include:
Cod
Dairy products including milk, cheese, and yogurt
Eggs
Seaweed products
If you do use salt, opt for iodized salt over sea salt .
The bottom line
Many people in the U.S. are missing out on nutritious foods in their diets. Because of this, they’re missing out on key nutrients, such as vitamin D, potassium, calcium, iron, and iodine. Incorporating a variety of protein foods and eating the full rainbow of fruits and vegetables throughout your week can help you ensure you’re getting a variety of nutrients in your diet. A registered dietitian can help you see where you might be missing out on certain nutrients and help you fill those gaps.
Why trust our experts?
References
Cogswell, M. E., et al. (2012). Sodium and potassium intakes among US adults: NHANES 2003–2008. The American Journal of Clinical Nutrition.
Hoy, M. K., et al. (2022). Potassium intake of the U.S. Population: What we eat in America, NHANES 2017-2018. Food Surveys Research Group Dietary Data Briefs.
International Food Information Council. (2025). IFIC Food & Health Survey.
Office of Dietary Supplements. (2025). Calcium: Fact sheet for health professionals. National Institutes of Health.
Office of Dietary Supplements. (2024). Iodine: Fact sheet for health professionals. National Institutes of Health.
Office of Dietary Supplements. (2025). Iron: Fact sheet for health professionals. National Institutes of Health.
U.S. Department of Agriculture. (2020). Dietary Guidelines for Americans, 2020-2025.
