Micronutrients

ADULT

ENTERAL

NUTRITION

MENU

Nutritional Science

Micronutrients

Back To Menu

Definition

Micronutrients is the name given to vitamins, minerals and trace elements required in the diet in very small amounts, unlike macronutrients, such as carbohydrates, protein and fat. Micronutrients are essential for the diet and are needed for the maintenance of health. The micronutrients needed in the human diet are listed below

Minerals	Vitamins
Sodium	Vitamin A
Chloride	Retinol
Potassium	B-carotene
Calcium	Vitamin D₃
Phosphorus	Vitamin E
Magnesium	Vitamin K
Iron	Vitamin C
Zinc	Thiamin (vitamin B₁)
Copper	Riboflavin (vitamin B₂)
Iodine	Niacin
Selenium	Folic acid
Manganese	Vitamin B₁₂
Chromium	Pantothenic acid
Molybdenum	Biotin
Fluoride	Choline
	Taurine
	Carnitine
	Inositol

Function

Below is a short non-exhaustive list of the function of some of the vitamins and minerals listed in Table 1 above.

Vitamin A is needed for the normal function of the visual system, and maintenance of cell function for growth, epithelial integrity, red blood cell production, immunity and reproduction.

Vitamin C is the major water-soluble antioxidant and acts as the first defence against free radicals in whole blood and plasma.

Vitamin C and vitamin E inhibit oxidation synergistically and act against oxidative stress as potent radical scavenging antioxidants.^1,2

Vitamin D is involved in bone health by maintaining calcium and phosphorus homeostasis and promoting bone mineralisation.⁴ Vitamin D is also implicated in a variety of non-skeletal activities including muscle function, immunity, inflammation and prevention of various diseases, such as certain cancers, autoimmune diseases, cardiovascular diseases and diabetes.^5-7Vitamin D deficiency is largely induced by factors such as high latitude (above 35°), seasonality (winter time) and an indoors lifestyle.

Zinc is an essential trace element that is a catalytic component of over 300 enzymes, and also has a role in the structural integrity of proteins and membranes.⁸ Zinc is required for DNA synthesis, immunity, and sensory functions.

Zinc (Zn) and selenium (Se) are trace minerals with antioxidant properties. They are co-factors of many enzymatic systems, such as the selenium-dependent glutathione peroxidase and the copper (Cu)-Zn superoxide dismutase pathways essential in antioxidative defence.^9,10

Calcium is one of the main mineral components of bone tissue and is therefore essential for adequate bone formation. Calcium participates in bone mineralisation, including formation and maintenance of the structure and rigidity of the skeleton.¹¹

Micronutrient deficiency

During acute and chronic illness, metabolic changes can occur which are caused by pro-inflammatory cytokines that canead to fever, loss of appetite, weight loss, and alterations in fat and trace element metabolism.¹² An adequate supply of micronutrients is needed to prevent unwanted clinical conditions due to deficiency or excess. Below is a non-exhaustive list of examples.

Vitamin A deficiency: generates ocular lesions that can lead to blindness.¹³

Vitamin D deficiency: Vitamin D deficiency is largely induced by factors such as high latitude (above 35°), seasonality (winter time) and an indoor lifestyle.

Iron deficiency: leads to anaemia.¹⁴

Iodine deficiency: gives rise to goitre and cretinism which is responsible for developmental delays and other health problems. Iodine deficiency is mainly observed in inland areas where lower quantities of marine foods are available.¹⁵

Role of micronutrients during illness

Infection and trauma cause inflammatory stress in patients which may result in tissue damage, enhanced inflammatory mediator production and suppressed lymphocyte function.

In critically ill patients, it has been shown that plasma micronutrient concentrations are low, as a result of increased losses, increased metabolic rate, low intakes and redistribution from plasma to tissue.¹⁶

The antioxidant vitamins are important not only for limiting tissue damage, but also in preventing increased cytokine production.¹⁷ Supplementation with antioxidants in the acutely ill and chronically ill patient should help improve the antioxidant defence and limit the extent of the inflammatory response.

Micronutrient in Enteral Nutrition

Antioxidant vitamins and trace minerals may improve patient outcome, especially in burns, trauma, and critical illness requiring mechanical ventilation.^18,19

Vitamin C and E supplementation of enteral feeds has recently been shown to reduce oxidative stress, thereby reducing the incidence of organ failure and shortening the length of hospital stay.²¹

Supplementation with zinc, selenium and copper has been shown to improve zinc and selenium status, improve leukocyte count and shorten hospital stay.²² Supplementation of enteral feeds is justified due to the important roles they play in the defence against oxidative stress, and during catabolic stress.

References

Sies H, Stahl W. Vitamins E and C, beta-carotene, and other carotenoids as antioxidants. Am J Clin Nutr 1995;62:S1315-21.
Niki E, et al. Interaction among vitamin C, vitamin E, and beta-carotene. Am J Clin Nutr 1995;62:S1322-6.
Burton GW, Joyce A, Ingold KU. Is vitamin E the only lipid-soluble, chain-breaking antioxidant in human blood plasma and erythrocyte membranes? Arch Biochem Biophys 1983;221:281-90.
De Luca HF. Overview of general physiologic features and functions of vitamin D. Am J Clin Nutr 2004;80:S1689-96.
Holick MF. Vitamin D: a D-Lightful health perspective. Nutr Rev 2008;66:S182-94.
Samuel S, Sitrin MD. Vitamin D's role in cell proliferation and differentiation. Nutr Rev 2008;66:S116-24.
Van Etten E, Stoffels K. Regulation of vitamin D homeostasis: implications for the immune system. Nutr Rev 2008;66:S125-34.
Hambidge M. Human zinc deficiency. J Nutr 2000;130:S1344-9.
Foster LH, Sumar S. Selenium in health and disease: a review. Crit Rev Food Sci Nutr 1997;3.
Meister A, Anderson ME. Glutathione. Ann Rev Biochem 1983;52:711-60.
Bueno AL, Czepielewski MA. The importance for growth of dietary intake of calcium and vitamin D. J Pediatr 2008;84:386-94.
Gariballa S, et al. Riboflavin status in acutely ill patients and response to dietary supplements. JPEN 2009;33:656-61.
World Health Organisation. Global prevalence of vitamin A deficiency in populations at risk 1995–2005. WHO Global Database on Vitamin A Deficiency2009.
World Health Organisation. Worldwide prevalence of anaemia 1993-2005. WHO global database on anaemia2008.
Lancet T. Iodine deficiency—way to go yet. Lancet 2008;372:88.
Berger M, Shenkin A. Update on clinical micronutrient supplementation studies in the critically ill. Curr Opin Clin Nutr Metab Care 2006;9:711-6.
Grimble RF. Effect of antioxidative vitamins on immune function with clinical applications. Int J Vit Nutr Res 1997;67:312.
Berger MM, Spertini F, et al. Trace element supplementation modulates pulmonary infection rates after major burns: a double-blind, placebo-controlled trial. Am J Clin Nutr 1998;68:365-71.
Nathens AB, Neff MJ, et al. Randomized, prospective trial of antioxidant supplementation in critically ill surgical patients. Ann Surg 2002;236:814-22.
Taylor BE, McClave SA, et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (ASPEN). Crit Care Med 2016;44:390-438.
Crimi E, et al. The beneficial effects of antioxidant supplementation in enteral feeding in critically ill patients: a prospective, randomized, double-blind, placebo-controlled trial. Anesth Analg 2004;99:857-63.
Berger MM, et al. Cutaneous copper and zinc losses in burns. Burns 1992;18:373-80.
Gengenbacher M, et al. Low biochemical nutritional parameters in acutely ill hospitalized elderly patients with and without stage III to IV pressure ulcers. Aging Clin Exp Res 2002;14:420-3.