14 Most Common Vitamin Deficiencies

Posted by Kevin Garcia on

10% of the U.S. population has a vitamin deficiency; learn why the most prevalent deficiencies occur.

Vitamins Deficiency

According to the 2015-2020 Dietary Guidelines, “Although the majority of Americans consume sufficient amounts of most nutrients, some nutrients are consumed by many individuals in amounts below the Estimated Average Requirement or Adequate Intake levels. These include potassium, dietary fiber, choline, magnesium, calcium, and vitamins A, D, E, and C. Iron also is underconsumed by adolescent girls and women ages 19 to 50 years.”

It’s important to remember that a vitamin or mineral deficiency is an extreme state. It’s entirely possible to have inadequate levels of vitamins or minerals without having an overt deficiency showing clinical symptoms. However, insufficient states are rarely measured, studied or addressed in traditional medical practice, leaving many people unaware of the fact that they have a problem.  

Common Reasons Behind Vitamin/Mineral Deficiencies

One of the most common reasons behind vitamin and mineral deficiencies and subclinical nutrient levels is an inadequate diet. Many times, this stems from a lack of knowledge about nutrition and healthy cooking, from a general dismissal of the important reasons behind eating a well-balanced diet, or because of convenience factors (i.e. rushing home from work to put dinner on the table for the family may result in frozen pasta, but no vegetables). 

Other common reasons for nutrient deficiencies include disease and illness (such as malabsorption syndromes), food insecurity (poverty), and cultural, religious or philosophical practices (veganism).

In the case of vitamin D deficiencies, environmental factors are also a major cause, as a significant portion of vitamin D is obtained through sunshine. In climates that don’t experience as much sunlight, residents are likely to have a vitamin D deficiency (though this is not only climate-related — more on that later).

Vitamin A

According to data from the National Health and Nutrition Examination Survey (NHANES), less than 1% of Americans have a vitamin A deficiency, which would technically classify it as a rare deficiency. However, it’s possible that a much larger number of people aren’t getting adequate dietary vitamin A. Elliot Reimers is a NASM Certified Nutrition Coach, who says he commonly sees Vitamin A deficiencies — and it’s a problem. “It’s something our body desperately needs in order to do basic things such as fight illness, and protect epithelial tissues, including the skin, keeping it healthy,” he says.

The National Institutes of Health (NIH) says that “Vitamin A is important for normal vision, the immune system, and reproduction. Vitamin A also helps the heart, lungs, kidneys, and other organs work properly.”

Symptoms of a vitamin A deficiency include:

  • Dry skin and other skin issues

  • Dry eyes

  • Night blindness

  • Immune insufficiency

  • Fertility issues

  • Slow wound healing

  • Stunted growth (in children)

Foods rich in vitamin A are easy to come by, and include:

  • Green, orange, or yellow vegetables (carrots, squash, broccoli, leafy greens)

  • Orange fruits (mangos, oranges, cantaloupe, apricots)

  • Salmon

  • Fortified dairy products (milk, yogurt, cheese)

  • Fortified breakfast cereals

  • Some organ meats (such as liver)

Vitamin B6

While the NIH lists vitamin B6 deficiency as “uncommon,” NHANES data would disagree. 

According to the Second Nutrition Report, about 10.5% of Americans are deficient in vitamin B6, making it one of the more common vitamin deficiencies in the United States. Part of this disparity could be attributed to individual medical diagnoses that prevent absorption, such as those with severely decreased kidney function, autoimmune disorders, and alcohol dependence.

Vitamin B6 is critical “for more than 100 enzyme reactions involved in metabolism. Vitamin B6 is also involved in brain development during pregnancy and infancy as well as immune function.”

Symptoms of a vitamin B6 deficiency include:

  • Anemia

  • Skin issues, such as rashes or scaly skin on the lips

  • Cracking at the corners of the mouth

  • Swollen tongue

It’s not difficult to get vitamin B6 through the foods rich in this essential vitamin: 

  • Potatoes

  • Beef

  • Milk

  • Ricotta cheese

  • Eggs

  • Fortified cereals

  • Salmon

  • Tuna

  • Carrots

  • Spinach

Vitamin B12

The prevalence of vitamin B12 deficiency varies greatly, depending on which source you’re reading. The NIH lists prevalence as being between 1.5% and 15% of the American population. A 2017 study of U.S. and U.K. residents landed on 6% for people under the age of 60, and 20% for those over the age of 60.

Vitamin B12 is an important nutrient that “helps keep the body’s nerve and blood cells healthy and helps make DNA, the genetic material in all cells. Vitamin B12 also helps prevent a type of anemia called megaloblastic anemia that makes people tired and weak.” In order for the body to absorb it properly, it must first be separated from food protein via hydrochloric acid in the stomach, and must eventually bind to intrinsic factor (secreted by the stomach) in order to be absorbed in the GI tract. There are a variety of things that can interfere with optimal absorption of vitamin B12, and our ability to properly absorb B12 decreases as we age. 

A vitamin B12 deficiency can manifest in many different ways, including:

  • Fatigue

  • Physical weakness

  • Constipation

  • Weight loss

  • Megaloblastic anemia

  • Tingling hands or feet

  • Trouble with balance

There are many ways to get vitamin B12 as part of a balanced diet. Vitamin B12 is naturally found in animal products, including: 

  • Fish

  • Red meat

  • Poultry

  • Eggs

  • Milk

  • Cheese

  • Other milk or dairy products 

However, vitamin B12 is generally not present in plant foods, and therefore vegans must supplement their diet with vitamin B12.

Vitamin C

Vitamin C is a nutrient that acts as an antioxidant inside the body to protect against potential damage from free radicals, in addition to performing other essential functions, such as assisting in collagen production, helping the body absorb iron, and supporting the immune system. The percentage of people in America who have a vitamin C deficiency may be about 7% and research shows that it is increasing because people aren’t eating enough fresh fruits and vegetables. 

Severe vitamin C deficiency is called scurvy and is characterized by the following symptoms: 

  • Gum inflammation (which can include swelling or bleeding)

  • Fatigue

  • Red or purple spots on the skin

  • Joint pain

  • Slow wound healing

  • Corkscrew hairs

  • Depression 

There are many ways to get vitamin C from foods, such as:

  • Bell peppers

  • Potatoes

  • Tomatoes

  • Berries

  • Kiwi 

  • Citrus fruits

  • Pineapple

  • Leafy greens

  • Broccoli 

  • Brussels sprouts


Calcium is a mineral crucial for strong teeth and bones, as well as healthy muscles, brain function, hormone secretion and nerve transmission. While the prevalence of calcium deficiency varies, the 2015-2020 Dietary Guidelines acknowledge that calcium is under-consumed in the United States.

Calcium deficiency can be a difficult problem to catch because if the body isn’t getting the required amount of calcium in food, it will start to “steal” it from bones, causing an increased risk of osteoporosis, osteopenia, and bone fractures. When a deficiency becomes more severe, symptoms can include:

  • Tingling or numbness in the fingers

  • Abnormal heart rhythms

  • Muscle spasms

  • Seizures 

  • Dental problems

  • Fatigue and depression

The most common ways Americans get calcium is through the following foods:

  • Dairy products

  • Leafy greens and cruciferous vegetables

  • Fortified foods


Zinc is a vital nutrient that plays a role in many functions, such as growth and development, immune system support, protein and DNA production, wound healing, eye health and supporting taste and smell. Exact data on prevalence of zinc deficiency in America is difficult to ascertain, but an estimated one-third of the world’s population is thought to be deficient — largely in Southeast Asia, Sub-Saharan Africa, and parts of the Middle East.

A zinc deficiency can manifest in many different ways, including:

  • Weight loss

  • Hair loss

  • Diarrhea 

  • Decreased sense of taste or smell

  • Slow wound healing

  • Poor alertness

There are many foods that are rich in zinc, including:

  • Oysters

  • Meat, poultry, seafood

  • Legumes

  • Oatmeal and granola

  • Dairy products

  • Nuts and seeds

  • Dark chocolate

Vitamin D

According to NHANES data, about 8.1% of Americans are vitamin D deficient — a number that may seem low if you test your patients regularly for this vitamin level. Of course, this will also depend on where you live and how outdoorsy your patients are. 

“The most common vitamin deficiency we see is Vitamin D,” says Dr. John A. Robinson, NMD. “We test for it consistently and it is almost always low or suboptimal. A major reason is that most people do not go out into the sun long enough to generate Vitamin D. And if they do supplement with Vitamin D, it is often too low of a dose to be effective.”

There is also the factor that sunscreen is recommended at all times when a person is outdoors — even if it’s overcast on that particular day. Sunscreen blocks vitamin D production in the body, which increases the possibility that a given person will have a vitamin D deficiency, especially if they’re adhering to these guidelines. 

Robinson says that vitamin D is the deficiency he looks out for the most, because not only is it crucial for multiple functions within the body, it’s also “easy to test for it and easy to correct.”

“Vitamin D operates like a hormone in your body and is needed for proper immune function,” says Robinson. Vitamin D plays a major role in “pain regulation, brain function, mood balancing, weight loss, insulin and blood sugar control, and much more.”

In fact, research has shown that adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis. The reason for this is that vitamin D is crucial for calcium absorption. 

Vitamin D deficiency is often missed (unless tested for) because its symptoms share so many similarities with other diagnoses. Symptoms include:

  • Fatigue

  • Muscle weakness, aches, or cramps

  • Bone pain

  • Mood changes

  • Frequent illness

  • Skin problems

It’s difficult to get all the vitamin D the body needs through food alone, but there are some foods that are good sources of vitamin D that can be incorporated into a healthy diet:

  • Cod liver oil

  • Salmon

  • Tuna

  • Foods fortified with vitamin D, such as orange juice, milk, yogurt, and cereal

“While ‘food first’ is a general rule, sometimes supplementation is warranted based on each individual’s needs and abilities,” says Manju Karkare, MS RDN LDN CLT FAND. “For example, vitamin D supplementation is very easy, inexpensive and much better than sun exposure for someone who may have genetic predisposition to skin cancer. Plus, sunscreen is essential for all of us. If adequate intake is not possible for any intolerance to good food sources, that is also a good reason to use to supplement.”

Folate/Folic Acid

According to NHANES data, having a folate deficiency is rare in the United States, with numbers coming in at under 1%. The number of people (especially women) with a folate deficiency or insufficiency decreased dramatically across multiple races and ethnicities between 1998 and 2006 because of a public health push to ensure that women who were pregnant (or trying to become pregnant) were getting enough folate in their diets, or supplementing with folic acid. 

In 1998, FDA began requiring that folic acid be added to all enriched cereals and grains. The reason for this is that folate plays a major role in cell division and growth, making it vital for pregnant women and infants. Research has shown time and time again that adequate folate may reduce a woman's risk of having a child with a brain or spinal cord birth defect. 

Symptoms of a folate deficiency include:

  • Megaloblastic anemia

  • Fatigue

  • Weakness 

  • Shortness of breath

  • Trouble concentrating

  • Headaches

  • Heart palpitations

  • Open sores inside the mouth

  • Changing the color of hair, fingernails, or skin

  • Mental and emotional disorders

  • Agitation and irritability

In addition to FDA’s push for adding folic acid to fortified foods, this vitamin is found in many food sources, such as:

  • Cantaloupe

  • Citrus and tropical fruits (like bananas and mangos)

  • Vegetables (especially asparagus, brussels sprouts, and leafy greens)

  • Beans & legumes

  • Nuts & seeds

  • Enriched grains, bread and pasta

  • Fortified breakfast cereals

NHANES data, however, does not take into account the latest genetic research showing that a large part of the population (40-60%) has a genetic variant that may significantly affect the conversion of folic acid or folate they consume into the active methylfolate the body can use.  Why is this important? Because methylation is required for many biochemical reactions that regulate the activity of our cardiovascular, neurological, reproductive, and detoxification systems and activated methylfolate is needed for the methylation process.

If enough active methylfolate is present, the methylation cycle will work efficiently. But folate from the diet or folic acid from supplements must be converted to the active form before it can be used in the body in the methylation cycle.

The best supplement brands put only active methylfolate (5-MTHF) in their multivitamins instead of folic acid because we now know that many people cannot efficiently convert folic acid to the methylfolate the body needs.  

Fiber (Dietary)

There’s quite sufficient evidence to suggest that most Americans aren’t getting enough fiber in their diets. The average American consumes between 10 and 15 grams of dietary fiber per day, but the USDA recommends 25 grams for women, and 38 for men. 

Fiber is a vital nutrient for many digestive functions in the body. According to Nutritional Epidemiologist Nicola M. McKeown, “research shows too little fiber can also lead to increased risk of developing Type 2 diabetes and cardiovascular disease,” in addition to being a leading cause of Americans’ number one gastrointestinal complaint: constipation. Gut health is crucial to overall health, and fiber is a significant contributing factor to a healthy microbiome. 

Symptoms that you’re not getting enough fiber in your diet can manifest in a few different ways: 

  • Constipation

  • Food cravings and overeating

  • Frequent hunger

  • Weight gain

  • Unstable blood sugar

  • Fatigue

Fortunately, there are plenty of ways to get dietary fiber from widely available foods, such as:

  • Beans & other legumes

  • All vegetables

  • Most fruits

  • Whole grains

  • Nuts & seeds


According to NHANES data, 9.5% of American women ages 19-45 have an iron deficiency. Iron is important for many functions, including the production of “hemoglobin, a protein in red blood cells that carries oxygen from the lungs to all parts of the body, and myoglobin, a protein that provides oxygen to muscles.”

An iron deficiency does not become immediately apparent. As with calcium, the body has stores of iron it can steal from- like muscles, the liver, spleen, and even bone marrow. But as stores run low, anemia sets in and more obvious symptoms present themselves, such as:

  • Weakness

  • Fatigue

  • Restless legs

  • Trouble sleeping

  • Shortness of breath

  • Hair loss

  • Trouble concentrating 

  • Trouble retaining information

  • Weakened immune system

  • Body temperature fluctuations

Iron is naturally found in foods such as:

  • Lean meat

  • Organ meat

  • Shellfish

  • Poultry

  • Fortified cereals

  • Beans

  • Legumes

  • Lentils

  • Leafy greens

  • Broccoli

  • Tofu

  • Nuts

  • Seeds

  • Raisins

  • Molasses 

  • Quinoa


According to the Second Nutrition Report, magnesium is under-consumed in the United States, but is not listed as an extreme concern (perhaps a bit surprising, considering how important this mineral is to the body). Magnesium plays a role in 300 biochemical reactions in the human body and is critical for proper muscle function, immune support, bone health, and cardiovascular health.

The trouble with magnesium deficiencies is that most people don’t know they have a deficiency until they’re sick enough to visit the emergency room or urgent care. The symptoms are similar to many other ailments, and the severe symptoms warrant medical attention. The most common symptoms of a magnesium deficiency are:

  • Fatigue

  • Weakness

  • Decreased appetite

  • Nausea

  • Muscle cramping

  • Mood changes

  • Osteoporosis

  • Irregular heartbeat

  • High blood pressure

  • Numbness

  • Tingling

  • Seizures

  • Low blood calcium and potassium levels

Magnesium is widely distributed in both plant and animal foods, but more highly concentrated in plant foods. If the food contains fiber, it likely contains magnesium. But when foods are processed (like white flour and white rice), it strips the magnesium out. That’s why a healthy diet of whole natural foods supplies the most magnesium. 

Some common magnesium-rich foods include:

  • Dark leafy greens 

  • Bananas

  • Nuts

  • Avocados

  • Beans, peas and other legumes

  • Potatoes (with skin)

  • Seeds

  • Soy products (such as tofu and soy-milk)

  • Salmon 

  • Halibut

  • Whole grains and oats

  • Milk & yogurt

  • Dark chocolate

However, only  30% to 40% of the dietary magnesium you consume is typically absorbed and used by the body, which explains the reason why many Americans are deficient in magnesium despite a balanced diet.  Experts recommend supplementing your diet with additional magnesium.


Some estimates put potassium deficiency at 98% of Americans. While that figure may be extreme, the Dietary Guidelines included potassium on their list of serious concerns for a reason — the human body uses potassium for nearly every function it performs, “including proper kidney and heart function, muscle contraction, and nerve transmission.”   

Part of the concern could be stemming from the possible causes for potassium deficiency that are quite common, such as depletion due to certain medications (like laxatives or diuretics) and malabsorption due to IBD (like Crohn’s disease and ulcerative colitis). 

Symptoms of a severe potassium deficiency include: 

  • Muscle aches, stiffness, or weakness

  • Fatigue

  • Muscle cramps or spasms

  • GI issues

  • Heart palpitations

  • Tingling or numbness of the extremities

  • Difficulty breathing

  • Mood changes

  • Increased blood pressure

  • Decreased calcium in bones

Fortunately, potassium is very easy to come by, and found in most fruits, vegetables and dairy products, and many favorite foods, including:

  • Apricots

  • Prunes

  • Raisins

  • Bananas

  • Oranges

  • Honeydew 

  • Cantaloupe 

  • Squash

  • Eggplant

  • Pumpkin 

  • Zucchini 

  • Potatoes

  • Leafy greens

  • Tomatoes 

  • Milk

  • Yogurt

  • Poultry

  • Fish 


Much like potassium, choline consumption was called out as a particular area of concern in the most recent Dietary Guidelines. While it’s not clear how prevalent choline deficiency is, it’s generally agreed upon in the medical community that most people are under consuming this important nutrient. The brain and nervous system use choline to regulate memory and mood, support muscle control, and furthermore, choline is vital for the formation of membranes that surround cells. 

Symptoms of a choline deficiency include:

  • low energy levels

  • memory loss

  • cognitive decline

  • muscle aches

  • nerve damage

  • mood changes

While eggs are the richest source of choline in the American diet, other main dietary sources of choline consist primarily of animal-based products —meat, poultry, fish and dairy products.  Some plant-based foods also contain choline. Here is a list of choline rich foods:

  • Meat

  • Poultry

  • Fish

  • Dairy products

  • Cruciferous vegetables (Brussels sprouts, broccoli, cauliflower)

  • Potatoes 

  • Navy, kidney and soybeans & peas

  • Nuts

  • Seeds

  • Whole grains

How to Address Vitamin Deficiency

Ideally, daily nutritional needs would be met by eating a healthy, well-balanced diet rich in fruits, vegetables, and protein. However, the standard American diet does not always (or almost ever) supply all the vitamins and minerals a person needs. Our lifestyles are often too fast-paced and overbooked to cook healthy meals at home, and we often end up relying upon takeout or frozen meals.

Robinson always focuses on food first with his patients. “The foundation of proper nutrition is the diet. Supplements are just that — supplements to the diet,” he says. “Nutritional supplements can be very effective, but need to be high in quality in order to provide the expected results.”

Even healthy people can benefit from a high-potency daily multivitamin, as it may help support vitamin and mineral deficiencies they don't even know they have. A high quality multivitamin can provide more nutrients than diet alone, which can be helpful for achieving optimal wellness.

Share this post

← Older Post Newer Post →