Micronutrients are the smaller building blocks, such as minerals and vitamins, we need to sustain life and have optimal function. Micronutrient deficiencies (MNDs) are quite common worldwide. They occur due to insufficient intake or sufficient intake combined with impaired absorption due to infection, disease, or inflammation. In developing countries, food shortages are to blame, among other reasons. In industrialized countries, they are more likely due to poor diets based on low-quality processed foods. The universal recommendation of prenatal vitamins, including iron and folic acid, is testimony to our nutrient-poor diets. 

The Five Most Common MNDs

Iron, iodine, folate, vitamin A, and zinc deficiencies are the most common MNDs. They are responsible for perinatal complications, poor growth in children, and increased mortality and morbidity. 1 They can be just as devastating to adults. The following is a list of the deficiencies, their symptoms, and how to correct them.

Iron Deficiency

Without enough iron, we can't make hemoglobin and transport oxygen properly. As a result, fatigue is a common symptom of iron deficiency. Iron deficiency anemia may lead to a rapid or irregular heartbeat. In pregnant women, premature births and low birth weight babies can result. In children with low iron anemia, delayed growth, and development may occur. Additionally, iron deficiency anemia is associated with increased susceptibility to infections.

Other symptoms include:

• Weakness

• Pale skin

• Chest pain, fast heartbeat, or shortness of breath

• Headache, dizziness, or lightheadedness

• Cold hands and feet

• Inflammation or soreness of your tongue

• Brittle nails

• Unusual cravings for non-nutritive substances, such as ice, dirt, or starch

• Poor appetite, especially in infants and children with iron deficiency anemia 2

Sources: Red meat, pork, poultry, and seafood contain the most iron, with liver being the best source. Iron bound to hemoglobin and myoglobin is known as heme iron; all other forms are considered nonheme iron. Heme iron is the most highly absorbed. Dark green leafy vegetables are a good source of iron, but we don't absorb as much since it is in the nonheme form. Additionally, vegetables contain phytates, polyphenols, vitamin C, and calcium, all inhibiting iron absorption. 3 

Iodine

Without sufficient iodine, we can't produce enough thyroid hormone. With low thyroid hormones, we have less energy and can feel cold. Pregnant mothers with low thyroid can cause their babies to have brain and bone developmental problems. In extreme cases, miscarriages and stillbirths can occur. Stunted growth and other developmental delays can also happen. A condition called cretinism happens with some iodine deficiencies where the baby is severely intellectually compromised. 

Sources: Iodine is abundant in seawater, so people who live in coastal areas have less deficiency. Cod, tuna, shrimp, and other seafood are good sources of iodine, as is seaweed. Dairy is a good source as well. Of course, iodized salt is a great source of iodine, as the name implies. 4

Folic Acid/Folate

Too little folate, also called folic acid, can lead to anemia. In utero, folate is needed for proper nervous system development, and deficiencies can lead to spina bifida and anencephaly, a condition where the brain is severely underdeveloped. Folic acid, a supplemental form of folate, is given to pregnant mothers to avoid these terrible conditions in babies. Better forms (MTHF) of supplementation are available, but food is the best source. 

Symptoms of mild deficiency include:

•  fatigue

• gray hair

• mouth sores

• tongue swelling

• growth problems

• peripheral neuropathy

Symptoms of frank deficiency include:

• persistent fatigue

• weakness

• lethargy

• pale skin

• shortness of breath

• irritability 5

Sources: The best source of folate is beef liver. Additionally, eggs are a good source as well. Many vegetables contain folate, including dark leafy greens, legumes, asparagus, broccoli, oranges, and bananas. 6

Vitamin A

Vitamin A is also known as retinol. It is needed for vision, growth, cell division, reproduction, and immunity. Deficiency can cause acne, eczema, and other skin conditions. Related to the skin issues is poor wound healing. Eye problems starting with dry eyes in some cases and ending in night blindness initially and total blindness with severe deficiencies. Fertility can also be affected by low vitamin A. Lastly, upper and lower respiratory infections can occur with low vitamin A. 7

Sources: Vitamin A is highest in organ meats like liver and kidney. Fish, especially eel and caviar, have high amounts as well. Cheese, eggs, and butter also contain high levels of retinol, the active form. 8 No vegetables contain true vitamin A; they contain a preformed version called beta-carotene. It needs to be converted to retinol in our body. Many individuals do not possess enough enzymes for adequate conversion. Beta-carotene is found in colorful vegetables, especially orange and red ones. Carrots are a famous source of beta-carotene, hence, the name.

Zinc

Zinc, a mineral, is needed for healing injuries and creating DNA, fighting off infections, producing cells, growth, sexual development, and reproduction. Symptoms of deficiency include:

• unexplained weight loss

• wounds that won't heal

• lack of alertness

• decreased sense of smell and taste

• diarrhea

• loss of appetite

• open sores on the skin

Sources: Food sources of zinc are red meat, shellfish, dairy, and eggs. Legumes, seeds, nuts, and whole grains also contain zinc, but they are less available for the same reasons iron isn't- most plant minerals are often less bioavailable. In general, fruits and vegetables contain less zinc, although exceptions exist. Potatoes, for instance have a fair amount. 9

How to avoid MNDs

 As we saw in this post, the foods highest in the five micronutrients discussed today are animal-based. For this reason, four of the five most common MNDs are more common in vegetarians and vegans. Vegetarians often have lower iron storage than omnivores, although they have comparable total iron intakes. The bioavailability of iron and zinc in vegetarian diets is poor because of their higher content of absorption inhibitors such as phytate and polyphenols and the absence of animal-based foods. 10 Vegans appear to have an increased risk of low iodine status, deficiency, and inadequate intake compared with adults following less restrictive diets. 11

As I discussed earlier, retinol is the true form of vitamin A, and beta-carotene is inferior. Moreover, if eaten with fats, beta-carotene is more effectively absorbed. 12 Folate deficiency, one of the leading deficiencies, is rare in vegans. Although the best source is liver, it is plentiful in plant-based foods. My advice, as always, is to include animal-based foods in your diet. Organ meat, shellfish, seafood, eggs, and, if tolerated, fermented dairy. Although there is no guarantee that MNDs won’t happen, these foods contain the highest amounts of the most common nutrients deficient worldwide.