Micronutrients and Their Vitality to Good Health : Types, Functions, Benefits, and Toxicities

By Dr. Sonam Bhatia, Ph.D.

Micronutrients are essential nutrients that your body needs. Vitamins and minerals are important for healthy development, energy production, immune function, blood clotting, and other functions related to health (1). 

What are micronutrients?

Micronutrients are the class of vitamins and minerals required by our body in small amounts, hence referred to as "micro". However, their role in maintaining the physiology of our body is critical, and deficiency in any of them can lead to severe and deadly conditions. Food is the major source of micronutrients as your body can't produce vitamins and minerals, so they are also called essential nutrients. Vitamins are organic (containing carbon) compounds that are mainly synthesized in plants and animals and are resistant to physical/chemical degradation through the air, water, and acid (2). However, minerals are inorganic in nature, present in soil and water, and play an important role in enzymatic processes. Minerals are further categorized as macro and trace minerals, depending on their requirement (3). Hence, adequate consumption of micronutrients is certainly important to maintain proper health.

What's their importance?

Minerals play an important role in the production of enzymes and hormones and several other physiological processes. Though the body requires only small amounts of micro-nutrients but consuming a balanced amount is crucial. This article provides a basic overview of micronutrients, type, and how they impact your health during excess consumption and deficiency (4). 

 

Types and functions of micronutrients

Our diet should consist of the following four types of micronutrients:

1. Water-soluble vitamins: Vitamin B complex and Vitamin C are readily soluble in water, hence falling under the category of water-soluble vitamins. These vitamins have a short retention time and easily get excreted in the urine; therefore, you required a good amount. There are a total of eight different vitamins in the vitamin B complex with a role to act as coenzymes during enzymatic function and carry out important cellular processes. Vitamin C majorly acts as an antioxidant and protects our body against infective pathogens.

The function of water-soluble vitamins are listed as (5):

Vitamin B complex

Thiamine (Vitamin B1): Production of energy from carbohydrates through the process of glycolysis

Riboflavin (Vitamin B2): Production of energy in the body and role as antioxidant towards free radicals.

Niacin (Vitamin B3): Conversion of fuel (carbohydrates) into energy (ATP)

Pantothenic acid (Vitamin B5): carry out the production of fatty acid molecules

Pyridoxine (Vitamin B6): Helps proper functioning of carbohydrates, proteins, and fats in the body along with the development of the brain, nerves, skin, etc.

Biotin (Vitamin B7): Plays a vital role in the metabolism of bio-molecules and the proper functioning of enzymes.

Folate (Vitamin B9): role in the production of healthy red blood cells and is required in conditions of rapid growth development such as during pregnancy and fetus growth.

Cobalamin (Vitamin B12): it is essential for nerve tissue growth, production of RBCs, and absorption of iron in the blood.

Ascorbic acid (Vitamin C): Plays a major role in maintaining the health of skin, cartilage, teeth, bone, and blood vessels. In addition, it also protects the body from various infections by enhancing the body’s immunity towards the antigen.

 

2. Fat-Soluble Vitamins

Vitamin A, D, E, and K have been categorized under fat-soluble vitamins as they are readily soluble in fats/lipids due to their hydrophobic nature. Their bioavailability in the blood is enhanced if they are co-administered along with a source of fat. These vitamins can be stored in the body for a longer time in the liver and fatty acid tissues (adipose) for future requirements (6).

The type and function of fat-soluble vitamins are listed as:

·      Vitamin A: required for good eyesight (vision).

·      Vitamin D: The body produces this vitamin on sun exposure. It is critical for maintaining proper bone and tooth function also helps in calcium absorption. 

·      Vitamin E: also called “Beauty Vitamin” and chemically known as tocopherol. It acts as a powerful antioxidant and helps in the maintenance of muscle tone and fertility.

·      Vitamin K: Plays an essential role in blood clotting and bone metabolism.

3. Minerals: Minerals are generally categorized into two classes depending on their requirement in the body (7):

Macrominerals: They are required in more amount in comparison to trace minerals as they are linked to a variety of physiological processes.

The various type of macrominerals and their amount and function are listed as:

·      Calcium: required in the structural framework of bones and teeth and their functioning. It is also required for a strong heart, muscles, and nerves.

·      Phosphorus: It is an important constituent of the cell membrane, also assists in bone and muscle development.

·      Magnesium: It acts as a co-factor of many enzymes, helps the proper functioning of enzymes and other cellular process.

·      Sodium: for maintaining the blood osmolarity and acting as an electrolyte which aids in fluid balance and blood pressure maintenance.

·      Chloride: Chloride ions coexist with sodium in the body and it also helps in maintaining fluid balance and synthesis of digestive juices such as bile.

·      Potassium: an important in the proper functioning of Na+/K+ pump in the body which regulates nerve transmission.

·      Sulfur: It is a part of sulfur-containing amino acids (cysteine, methionine, etc.) and glutathione.

4. Trace minerals: These minerals are required in an amount less than 100 mg per day.

The list of trace minerals and their function are:

·  Iron: an important part of hemoglobin and required for oxygen binding during its transport to the cells, required for the proper functioning of RBCs.

·  Manganese: It is a cofactor and helps in the enzymatic metabolism of carbohydrates, amino acids, and cholesterol in the body.

·  Copper: It plays a role in the growth and development of connective tissues of the brain and nervous system.

·  Zinc: Necessary for normal tissue growth, immune system, and healing of wounds.

·  Iodine: aids in the production of thyroid hormone.

·  Fluoride: required for strong bones and good teeth texture.

·  Selenium: produces antioxidant enzymes in the body which prevents cell damage.

Food sources of the micronutrients and their RDA (Recommended Dietary Allowance) as per age and gender (8):

The detail regarding food source and quantity of micronutrients required by an individual is presented as:

Nutrient	Source	RDA (above > 19 years)
Vitamins		Male	Female
Water Soluble
Thiamine (Vitamin B1)	Fortified breakfast cereals, Pork, Fish, Beans, lentils	1.2 mg	1.1 mg
Riboflavin – Vitamin B2	Dairy Milk, Yogurt, Cheese, Eggs	1.3 mg	1.1 mg
Niacin – Vitamin B3	Red meat: beef, beef liver, pork, Poultry, Fish	16 mg	14 mg
(Vitamin B5	Mushrooms, Avocado, Nuts, Seeds, Dairy Milk, Yogurt	5 mg	5 mg
Vitamin B6	Beef liver, Tuna, Salmon, Fortified cereals	1.3 mg	1.2 mg
Vitamin B7	Beef liver, Eggs (cooked), Salmon, Avocados	30 mcg	30 mcg
Vitamin B9 (folate)	Beans, Peanuts, Sunflower seeds, Fresh fruits, fruit juices, Whole grains	400 mcg	400 mcg
Vitamin B12	Fish, shellfish, Liver Red meat, Eggs	2.4 mcg	2.4 mcg
Vitamin C	Citrus (oranges, kiwi, lemon, grapefruit), Bell peppers, Strawberries, Tomatoes	90 mg	75 mg
Vitamin A	Retinol (liver, dairy, fish), carotenoids (sweet potatoes, carrots, spinach)	900 mcg	700 mcg
Vitamin D	Cod liver oil, Salmon, Swordfish, Tuna fish	600 IU daily for men and women	600 IU daily for men and women
Vitamin E	Wheat germ oil, Sunflower, safflower, and soybean oil, Sunflower seeds, almonds	15 mg (or 22 international units, IU)	15 mg (or 22 international units, IU)
Vitamin K	turnip greens, kale, spinach, broccoli, Brussels sprouts, cabbage, lettuces	120 micrograms (mcg)	90 micrograms (mcg)

Food Sources and recommended intakes of the minerals are (8)

Minerals	Source	RDA (above > 19 years)		Upper Limit
Macrominerals		Male	Female
Magnesium	Almonds, peanuts, cashews, Pumpkin seeds, Peanut butter, beans (black, kidney)	400-420 mg	310-320 mg	500 mg
Calcium	Milk products, leafy greens, broccoli	1,000 mg	1,000 mg	2,500 mg
Chloride	Seaweed, salt, celery	2.3 gm	2,3 gm	Not known
Sodium	Salt, processed foods, canned soup	1500 mg	1500 mg	Not known
Phosphorus	Salmon, yogurt, turkey	700 mg	700 mg	4,000 mg
Potassium	Lentils, acorn squash, bananas	3000 mg	2300 mg	Not known
Sulfur	Garlic, onions, Brussels sprouts, eggs, mineral water	Not reported	Not reported	Not known
Trace minerals
Iron	Oysters, white beans, spinach	8 mg	18 mg	45 mg
Manganese	Pineapple, pecans, peanuts	1.8 mg	2.3 mg	11 mg
Copper		900 mcg	900 mcg	10,000 mcg
Zinc		8 mg	11 mg	40 mg
Iodine		150 mcg	150 mcg	1,100 mcg
Selenium		55 mcg	55 mcg	400 mcg
Fluorine		3 mcg	4 mcg	10 mcg

Micronutrient deficiencies and toxicities

While consumed in smaller quantities than macronutrients, micronutrients are equally important for the physical and mental development of wellbeing. Iron, zinc, calcium, iodine, vitamins A, B, C, and D are some essential micronutrients, which if consumed in deficient amounts can lead to malnutrition. Micronutrient deficiencies hamper the overall growth of the body including poor physical and mental development in children, vulnerability or exacerbation of the disease, mental retardation, blindness, and general losses in productivity and potential. Health impacts of micronutrient deficiency are not as visible as those of energy-protein undernourishment; therefore, the term 'hidden hunger' is sometimes used interchangeably. The World Health Organization (WHO) estimates that more than two billion people suffer from micronutrient deficiencies worldwide (9), these deficiencies can be diagnosed by taking a vitamin panel blood test.

Toxicities

The number of reported micronutrient toxicity cases is less common than their deficiencies.

But still, they are likely to occur with the consumption of a large amount of particularly fat-soluble vitamins A, D, E, and K, as these vitamins are not water-soluble tend to remain for a longer duration in the body.

It is also noteworthy that micronutrient toxicity generally develops by using supplements in excess— they hardly seem to be toxic if consumed using food sources. The severity and toxicity profile of each nutrient is different and hence need to have proper monitoring (10).

One study performed on pyridoxine (vitamin B6) suggest in animal models at a dose of 25mg/day, it can lead to neuronal degeneration and neurotoxicity (11).  In another study, it was found that subjects living in selenium-rich areas complained of brittle hair, new hair with no pigments, and thickened and brittle nails with spots and streaks, this condition is called "selenosis", which is gain a toxic implication of selenium (12).

In addition, it is essential to have your micronutrient intake in line with prescribed requirements and under the supervision of a physician.

Conclusion

Vitamins and minerals come under the category of micronutrients and are needed by the body for essential physiological functions. Hence, one should aim to get the proper quantity of micronutrients for maintaining good health. Food and dietary supplements are the two major sources of micronutrients, but one should be vigilant in consuming their daily recommended quantities as their deficiencies lead to various disorders in the body, and consumption above the upper limits can lead to toxic implications.

References

1. Shenkin, A., 2006. The key role of micronutrients. Clinical nutrition, 25(1), pp.1-13.

2. Brinkevich, S.D., Sverdlov, R.L., Lagutin, P.Y. and Shadyro, O.I., 2011. Effects of B vitamins on the radiation-induced transformations of hydroxyl-containing organic compounds. High Energy Chemistry, 45(5), pp.380-385.

3. https://www.news-medical.net/health/Macrominerals-and-Trace-Minerals-in-the-Diet.aspx

4. Park, K., 2015. Role of micronutrients in skin health and function. Biomolecules & Therapeutics, 23(3), p.207.

5. Said, H.M., 2015. Water-soluble vitamins. Nutrition for the primary care provider, 111, pp.30-37.

6. Stevens, S.L., 2021. Fat-soluble vitamins. Nursing Clinics, 56(1), pp.33-45.

7. Miller, D.D., 2017. Minerals (pp. 627-679). CRC Press.

8.https://www.hsph.harvard.edu/nutritionsource/

9. Neumann, C., Harris, D.M. and Rogers, L.M., 2002. Contribution of animal source foods in improving diet quality and function in children in the developing world. Nutrition Research, 22(1-2), pp.193-220.

10. http://www.healthofchildren.com/M/Mineral-Toxicity.html

11.Schaumburg, H., Kaplan, J., Windebank, A., Vick, N., Rasmus, S., Pleasure, D. and Brown, M.J., 1983. Sensory neuropathy from pyridoxine abuse: a new megavitamin syndrome. New England Journal of Medicine, 309(8), pp.445-448.

12. Yang, G.Q., Wang, S.Z., Zhou, R.H. and Sun, S.Z., 1983. Endemic selenium intoxication of humans in China. The American journal of clinical nutrition, 37(5), pp.872-881.