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Top 5 Nutrient Deficiencies

B6, B12, C, D, and Iron

31% of people in the United States are at risk for a deficiency in at least one vitamin or mineral essential for good health. It may be hard to imagine that we don’t get enough nutrition when we see an abundance of food available 24/7, but it’s true. A study from 2017 showed the top five nutrients many of us need more of.

If you eat well and exercise, should you be concerned about being low in one or two vitamins or minerals? In a word, yes. That’s because vitamins and minerals are essential for optimal health. Being low may not cause immediate symptoms, but it puts you at risk for many serious diseases that can affect your brain, heart, blood, immune system, metabolism, bones, mental health, etc. Nutrients are key pieces your body needs to maintain all of your systems in good working order. Missing just one or two pieces can throw off the delicate balance you need to be healthy and feel great. That’s because most nutrients don’t have just one vital role to play within the body, they are involved in numerous functions and pathways.

How would you even know if you’re at risk for a nutrient deficiency? It’s not always obvious. Sometimes symptoms aren’t felt for a long time and sometimes they’re very vague and non-specific. For example, fatigue, irritability, aches, and pains, decreased immune function, and heart palpitations can be signs of many things, including a nutrient deficiency. This article by Bird, et al goes over the five most commonly deficient nutrients, some of the more obvious symptoms, and foods that are high in each so you can get enough.

1 – Vitamin B6

The number one most common nutrient deficiency in the US was Vitamin B6. This vitamin is important for your blood, brain, and metabolism. Vitamin B6 helps the formation of hemoglobin in the blood (the part that carries oxygen around). It also helps to maintain normal levels of homocysteine (high levels of homocysteine are linked with heart disease). In addition, this vitamin plays an important role in the production of neurotransmitters (chemical messengers allowing nerve cells to communicate with each other). Not to mention the fact that it’s also involved with over 100 enzyme reactions in the body, mostly for metabolism.

Some of the main symptoms of a serious deficiency in Vitamin B6 include peripheral neuropathy, weakness, irritability, depression, insomnia, and anxiety.  Other symptoms include dermatitis, nausea, vomiting and even convulsions.  Carpal tunnel syndrome, premenstrual tension syndrome and atherosclerosis may also be related to B6 deficiency.  Homocysteine levels in serum may be elevated with B6 deficiency.  When homocysteine levels are higher than normal, and clients are already taking methyl folate and methyl B12, I often add B6 as well as B2 (Riboflavin) which are cofactors, that can help lower homocysteine.   

Vitamin B6 is found in all food groups. People who eat high-fiber cereals tend to have higher levels of the vitamin because cereals are often fortified with it. Vitamin B6 is also found in high quantities in nutritional yeast, Chickpeas, Banana, Potato, Wild Salmon, Chicken, Avocado, Cooked Spinach, Dried Plums and Hazelnuts.

2 – Vitamin B12

Like Vitamin B6, Vitamin B12 is also very important for your blood and brain. It is needed for the creation of healthy red blood cells and the formation of the outer coating of nerve cells (myelin) which is very important for their optimal functioning.

Vitamin B12 can be a bit difficult to absorb from your food. To improve absorption, it’s important to have adequate acid and digestive enzymes in the stomach. This is because the vitamin is very strongly bound to the proteins in food, and stomach acid and enzymes help to break those bonds and free the vitamin so your body can take it in.

Having a Vitamin B12 deficiency can be caused by a type of anemia called “pernicious” anemia. Pernicious anemia affects the stomach and reduces its ability to absorb Vitamin B12. A deficiency in Vitamin B12 can then lead to a different type of anemia called “megaloblastic” anemia. Low levels of Vitamin B12 can also cause neurological damage (due to impaired myelination of nerve cells). Other symptoms include shortness of breath, fatigue, weakness, irritability, sore tongue, decreased blood cell counts.

Vitamin B12 isn’t naturally present in most plant-based foods, except it is found in some nutritional yeast products. It is naturally found in Clams, Beef Liver, Mussels, Mackerel, Crab, Trout, Salmon, Beef and Eggs.

If you are consuming Vitamin B12 supplements or eating foods that are fortified with Vitamin B12, your levels of stomach acid and digestive enzymes aren’t as critical as they are for the absorption of the vitamin directly from foods. This is because when adding Vitamin B12 to foods and supplements, it’s not tightly bound to their proteins, and this makes it much more easily absorbed.

If you have one or more copies of the MTHFR genetic variant, you will need the methylated form of B12 along with Methyl folate, B6 and B2 to help clear homocysteine.

3 – Vitamin C

Vitamin C is important for wound healing (via a protein called collagen), the production of neurotransmitters, metabolism, and the proper functioning of the immune system. Vitamin C also acts as an antioxidant to reduce the damage caused by free radicals that can worsen several diseases such as certain cancers and heart disease. Vitamin C also helps your body absorb the essential mineral iron, which is one of the top five nutrient deficiencies also included in this research article.

Collagen is a vital component of connective tissue and this describes some of the symptoms of its deficiency disease, scurvy. Symptoms of scurvy include weak connective tissue such as bleeding, wounds that won’t heal, and even the loss of teeth.

You can get Vitamin C from many fruits and vegetables. Sources high in Vitamin C include Rose Hip (you will often see this in supplements), Red Bell Peppers, Strawberries, Orange and Orange Juice, Kiwi, Green Bell Peppers, Broccoli, Brussels Sprouts, Grapefruit and Tomato.  If supplementing Vitamin C, start with 500mg and titrate up to the highest tolerated amount without causing gastrointestinal distress and diarrhea.  For individuals with chronic kidney disease or otherwise compromised kidney function, do not supplement high doses of Vitamin C to consume high amounts of Orange Juice.

When choosing foods for Vitamin C, choose the freshest options because levels of the vitamin naturally reduce over time the longer the food is stored. Try, as much as possible, to eat Vitamin C-rich foods raw. If you do cook them, then choose steaming and microwaving instead of prolonged boiling because the vitamin is destroyed by heat and is water-soluble.

4 – Vitamin D

Vitamin D, also known as the “sunshine vitamin,” is very important for your bones, weight management, mood, immune health, inflammation, and even sex hormones. It promotes the absorption of the mineral calcium. When your body has enough calcium, it can maintain normal bone mineralization and prevent problems in the muscles that lead to cramps and spasms. Getting enough Vitamin D and calcium can also help protect against osteoporosis. In addition to all of these bone and muscle impacts, Vitamin D helps to reduce inflammation and modulate both immune function and sugar metabolism.

Without enough Vitamin D bones can become thin, brittle, or misshapen. Vitamin D prevents these issues known as rickets (in children) and osteomalacia (in adults).

Your skin makes Vitamin D when it’s exposed to the ultraviolet rays of the sun and very few foods naturally contain it. The few Vitamin D-rich foods include fatty fish and fish liver oils (e.g., salmon, trout, cod liver oil). Other foods that naturally contain small amounts of Vitamin D include egg yolks, beef liver, and cheddar cheese. Some mushrooms can contain Vitamin D—particularly those exposed to UV light.

Most of the dietary Vitamin D that people in the US get is from fortified foods and beverages. These include some dairy products (mainly milk), certain plant milks (e.g., soy, almond, or oat milks), various breakfast cereals, and a few types of orange juice. Be sure to look at the nutrition labels to see if and how much Vitamin D is in each serving of the food or beverage.  Optimal levels of Vitamin D are closer to 60, however the “normal” lab value range is very wide at 30-100.  If you are below 50 consider supplementation and retest values in 30-60 days.  Vitamin D is a fat soluble vitamin, so choose a supplement that is a liquid gelcap vs a white powder tablet, that does not contain a fat.

5 – Iron

Iron is a mineral essential for healthy blood so that it can transport vital oxygen throughout your body every second of every day. This happens via a compound in your red blood cells called “hemoglobin.” Iron also supports your muscles (like Vitamin D) and your connective tissue (like Vitamin C). Having adequate iron is necessary for physical growth, neurological development, hormone production, and the function of your cells.

A deficiency in iron is commonly known as “anemia.” Menstruating women tend to be lower in iron simply because of their regular loss of blood – but don’t be confused by this – men can be deficient as well due to a lack of absorption.  The best way to check iron status is a lab called “Ferritin” which checks for iron storage.  This is the amount of iron you have available to use if needed.  Ferritin values below 80 should be supplemented with 20-60mg Iron plus vitamin C.  A dairy free diet can impact iron absorption due to the low intake of lactoferrin.  If you are on a dairy-free diet for whatever reason, and have low iron, consider supplementing with an iron that contains Vitamin C and Lactoferrin.

Most iron in the body is in the blood, but there is some stored in the liver, spleen, bone marrow, and muscles. This is why iron deficiency progresses slowly from depleting your stores (mild iron deficiency), to reducing the number of red blood cells (marginal iron deficiency), before you get to full-out iron deficiency anemia.

Iron is naturally found in many foods in one of two forms: heme and nonheme. Animal-based foods contain the more absorbable heme form. Plant-based foods naturally contain nonheme iron. This is where Vitamin C comes in. Vitamin C helps your body absorb the nonheme iron from plants, which is why, if plants are a main source of iron in your diet, it’s important to combine iron-rich plants with Vitamin C-rich plants in the same meal.

Some of the best sources of iron include fortified cereals, oysters, white beans, dark chocolate, beef liver, lentils, spinach, and tofu.

Final Thoughts

According to the article by Bird, et al 2017, the most common nutrient deficiency is Vitamin B6, but there are also many people deficient in vitamins B12, C, and D, as well as the mineral iron. Vitamins and minerals are essential nutrients because everybody needs them on a regular basis for good health. Lacking in any one nutrient can have far-reaching consequences.

Eating a nutrient-rich diet with a variety of foods can help everyone achieve their health and nutrition goals.  With up to one-third of people in the US are at risk for at least one nutrient deficiency, Micronutrient testing can be a very useful took for checking the intra-cellular status of these nutrients.  Serum levels in the blood may be normal, but that doesn’t mean the nutrient is getting into your cells – this is impacted by absorption and in some cases, genetics.

To know if you’re at risk for a nutrient deficiency, schedule a consult so that we can review your foods and supplements, and if necessary, consider Micronutrient Testing. 


Bird, J. K., Murphy, R. A., Ciappio, E. D., & McBurney, M. I. (2017). Risk of Deficiency in Multiple Concurrent Micronutrients in Children and Adults in the United States. Nutrients, 9(7), 655.

National Institutes of Health Office of Dietary Supplements. (2020, February 28). Iron fact sheet for health professionals.

National Institutes of Health Office of Dietary Supplements. (2020, February 4). Vitamin B6 fact sheet for health professionals.

National Institutes of Health Office of Dietary Supplements. (2020, March 30). Vitamin B12 fact sheet for health professionals.

National Institutes of Health Office of Dietary Supplements. (2020, February 27). Vitamin C fact sheet for health professionals.

National Institutes of Health Office of Dietary Supplements. (2020, October 9). Vitamin D fact sheet for health professionals.

Ueda, N., & Takasawa, K. (2018). Impact of Inflammation on Ferritin, Hepcidin and the Management of Iron Deficiency Anemia in Chronic Kidney Disease. Nutrients10(9), 1173.

Ueland, P. M., McCann, A., Midttun, Ø., & Ulvik, A. (2017). Inflammation, vitamin B6 and related pathways. Molecular aspects of medicine53, 10–27.