Dr. Neerja L. Bisht
What are Micronutrients?
The World Health Organization defines “micronutrients” as essential substances required in tiny amounts that enable the body to produce enzymes, hormones and other substances critical for proper growth and development .
Deficiency of Micronutrients
The micronutrient deficiency is not a problem of the developing world alone. Various populations in industrialized nations are at risk as well e.g. elderly, women and children, people on vegan diets etc.
WHO estimates this global burden affects more than 2 billion people. They suffer from dietary vitamin and mineral deficiencies with serious health consequences .
Micronutrient malnutrition can cause reduced resistance to infections, metabolic disorders, and delayed or impaired physical and psychomotor development.
What constitutes essential micronutrients?
(i) Essential Trace Elements and
(ii) Vitamins, that optimize health and prevent disease.
Why are some micronutrients called “Essential Micronutrients”?
- The body cannot produce these nutrients in adequate amounts and must be obtained from external sources like food
- Their absence is associated with several disease conditions.
- They are needed for normal growth and development.
What does Recommended Intake Value Mean?
Different people, e.g. lactating women, children etc. have different nutritional requirements. Therefore, the term recommended intake was coined so on average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%), healthy people.
Recommended Dietary Allowance (RDA): average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%), healthy people.
- Research has determined that the average intake of a micronutrient is a recommended intake value of y, the micronutrient for a person to remain healthy. The WHO declared iron deficiency anemia, zinc, and vitamin D deficiency to be a major source of micronutrient deficiency or micronutrient malnutrition on a global scale, but more so in the developing nations.
The following micronutrients consisting of elements and vitamins are considered essential for good health:
Iron: Diets low in meats and high in only cereals and legumes can cause low levels. Pregnant women and menstruating women including children with parasitic infections are particularly vulnerable. Fatigue and maternal morbidity and mortality are serious consequences.
Iodine: Low levels can cause thyroid gland dysfunction, loss of memory and thinking skills, birth defects, and increased risk of stillbirths to pregnant women.
Zinc: Persistent diarrhea in infants and children and infections can cause zinc deficiency leading to further infections, stunted growth, and delayed sexual development. In women, it can cause low-birth-weight infants.
Calcium: Low intake of dairy products can lead to decreased bone mineralization causing rickets in children and osteomalacia in adults.
Selenium: A deficiency has been associated with increased risk for cardiovascular disease and cancer.
Fluoride: A deficiency causes dental decay.
Vitamin A: Poor intake of milk and dairy products including eggs and vegetables can cause Vitamin A deficiency. Poor eyesight (night blindness) in children is caused by this deficiency.
Vitamin B3 (niacin): Pellagra is a condition caused by B3 deficiency. A diet that lacks eggs, beans, lean meats, and dairy products can cause this condition that results in inflamed skin conditions, digestive problems, and even mental disorders.
Vitamin B6: This deficiency is mainly seen in developing nations where a balanced healthy diet is not part of daily lives of most individuals. This is usually associated with other vitamin B deficiencies. A deficiency could produce neurological and skin disorders, and an elevated homocysteine level.
Vitamin B9 (folate): Genetic disorder to metabolize folate, or low intakes of meats, eggs, and dairy products balanced with vegetables and fruits can lead to an insufficiency. Megaloblastic anemia (this shows up in a blood film ordered for the cause of anemia) and should be further evaluated for a folate blood test (reference normal range: 2.5-17 ng/mL  ). Birth defects, poor pregnancy outcomes, malabsorption conditions (coeliac disease, tropical sprue, congenital malabsorption, inflammatory bowel disease, and such) and high homocysteine levels in the blood are some of the consequences.
Vitamin B12 (cobalamin): Presents with megaloblastic anemia and must be differentiated from folate deficiency to enable proper treatment. These persons will present with more neurological features: numbness and paresthesias in limbs occur first with some gait abnormalities. Values of less than 200 pg/mL indicate a vitamin B12 deficiency .
Vitamin C: A diet inadequate fresh vitamin C fruits such as lemons and oranges can lead to a deficiency. A severe lack of vitamin C leads to a condition called Scurvy that causes gums to bleed, anemia, and general weakness.
Vitamin D: The risk for vitamin D deficiency is higher in persons living in cold climates including areas where daylight hours are less, and the sunshine is not enough, or in cultures where their body is covered with clothing. Vitamin D deficiency causes rickets in children and osteomalacia in adults.
Prevention of micronutrient insufficiency
Micronutrient-rich foods provide a range of antioxidants and probiotic substances that are important for protection against selected non-communicable diseases and for enhancing immune function. It was advocated for individual countries to adopt food-based strategies to prevent micronutrient deficiencies. The goal was to produce the fastest improvement in the nutritional status of individuals. This was achieved by the following methods:
- Food fortification: by adding micronutrients to processed foods
- Nutrition education: providing appropriate education to mothers as a targeted population
- Applying food safety measures
- Supplementation: pills, capsules, or syrups providing adequate doses of micronutrients
What are the recommended dietary allowances for micronutrients?
The Recommended Dietary Allowance (RDA) is the average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people .
The Food and Nutrition Board, Institute of Medicine, National Academies RDA for elements are as follows:
|Age||Iron mg/day||Iodine µg/day||Zinc mg/day||Calcium mg/day||Selenium µg/day||Fluoride mg/day|
|Males 9-18 years||8-11||120||8-10||1300||40-55||2-3|
|Males 19-70 years||8||150||11||1000||55||4|
|Males >70 years||8||150||11||1200||55||4|
|Females 9-18 years||15||120||8-9||1300||40-55||2-3|
|Females 19-50 years||18||150||8||1000||55||3|
|Females 51-≥70 years||8||150||8||1200||55||3|
|Pregnancy and lactation||27||220-290||11-13||1000-1300||60-70||3|
Note how the requirements increase during pregnancy and lactation.
The Food and Nutrition Board, Institute of Medicine, National Academies RDA for vitamins are as follows:
|Age||Vitamin A µg/day||Vitamin B3 (Niacin) mg/day||Vitamin B6 mg/day||Vitamin B9 µg/day (Folate)||Vitamin B12 µg/day||Vitamin C mg/day||Vitamin D µg/day|
|Males 9-13 years||600||12||1.0||300||1.8||45|
|Males 14-≥70 years||900||16||1.3-1.7||400||2.4||75-90|
|Females 9-13 years||600||12||1.0||300||1.8||45|
|Females 14-≥70 years||700||14||1.2-1.5||400||2.4||65-75|
|Pregnancy and lactation||750-1300||17-18||1.9-2.0||500-600||2.6-2.8||750-1300|
In conclusion, although the amounts of micronutrients required by our body are minuscule, the body itself cannot synthesize these micronutrients. Therefore, eating a well-balanced diet consisting of meats, vegetables, and dairy products is crucial for the body to have a normal and healthy growth. People who are deficient in these micronutrients benefit from over the counter micronutrient supplements e.g.pregnant and lactating women where the needs become exaggerated. Sustained deficiency in one or more of these micronutrients can lead to ill health.
- Available at: http://www.who.int/nutrition/topics/micronutrients/en/. Accessed on 22 July 2015.
- Guidelines on food fortification with micronutrients. World health Organization and Food and Agricultural Organization of the United Nations. 2006.
- Available at: http://www.nlm.nih.gov/medlineplus/ency/article/003686.htm. Accessed 23 July 2015.
- Available at: http://www.nlm.nih.gov/medlineplus/ency/article/003705.htm. Accessed 23 July 2015.
- Available at: http://www.ncbi.nlm.nih.gov/books/NBK45182/. Accessed 24 July 2015.
- Available at: http://fnic.nal.usda.gov/dietary-guidance/dietary-reference-intakes/dri-tables-and-application-reports. Accessed 24 July 2015.