Micronutrients
- needed in small amounts
- measured in mg or μg per day (recommended daily intake)
- even though in small amounts, deficiency consequences are severe
- includes vitamins and trace minerals (Fe, Cu, Zn, I, Se, Mn, Mo, Cr, Co, B)
Macronutrients
- needed in large amounts
- provides energy in body to build and maintain structure
- includes carbohydrates, proteins and lipids
- and some minerals needed on larger scales (Na, Mg, K, Ca, P, S, Cl)
B.5.2 Compare the structures of retinol (Vitamin A), calciferol (Vitamin D) and ascorbic acid (Vitamin C).
B.5.3 Deduce whether a vitamin is water-soluble or fat-soluble from its structure
Examples
Water-soluble: Vitamins B and C
Fat-soluble: Vitamins A, D, K
Vitamins
- needed in small amounts
- not synthesized in body, hence need in diet
- broken down
- some fat-soluble (slower absorption, excess stored in fat tissue - can have some serious side effects; mostly non-polar, with long hydrocarbon chains or rings)
- some water-soluble (directly transported in blood, excess filtered by kidneys and excreted; has polar bonds and forms h-bonds with water)
- difference in structure determines their solubility
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| Source: IB Chemistry Textbook |
B.5.4 Discuss the causes and effects of nutrient deficiencies in different countries and suggest solutions.
Malnutrition: unbalanced/ irregular supply of nutrients
- especially in underdeveloped countries, but also high consumption of processed, energy-dense but micronutrient poor food
- resulting chronic diseases e.g. obesity, diabetes (so also prevalent in industrial countries)
Iodine
- needed for synthesis of hormone thyroxine (regulates metabolic rate)
- in most seafood/ some vegetables
- lack of: swelling thyroid gland (goitre); in children, largest cause of preventable mental retardation
- solution: add to salt (low cost)
Vitamin A (retinol)
- needed for healthy skin (acne treatment), good eyesight, protection against some damaging effects of toxins (anti-oxidants)
- orange and yellow fruits/vegetables, spinach, egg yolks
- lack of: xerophthalmia (dry eyes and night blindness)
- solution: fat-soluble, so its added to margarine (Vitamin A fortification); inexpensive, has reduced levels of xero. in many parts of the world; possibly rice for Vitamin A fortification
Iron
- most prevalent micronutrient deficiency
- essential for hemoglobin (which is responsible for blood transporting oxygen around the body)
- lack of: anemia, symptoms include fatigue, brittle nails, poor endurance and lowered immunity
- source: red meat, green leafy veg, nuts and seeds
- solution: iron supplementation may increase susceptibility to malaria (also widespread)
- iron fortification best when added with vitamin C to cereal flour and milk products.
Other micronutrient deficiencies and diseases
Niacin (Vitamin B3)
- Pellagra: dermatitis, diarrhea, dementia
Thiamin (Vitamin B1)
- Beriberi: weight loss, fatigue, swelling
Vitamin C
- Scurvy: bleeding gums, lowered resistance to infection and dark spots on skin
Vitamin D
- Rickets: softened, deformed bones
Selenium
- Kashin-Beak disease: atrophy and degeneration of cartilage (happens esp. in northern Russia and China, where the soil is Se deficient)
Macronutrient deficient
Protein
- when prolonged is life threatening
- Marasmus: mainly in infants from developing countries at the time of weaning; failure to gain weight, then weight loss and emaciation (weak and thin)
- Kwahiorkor: similar to Marasmus, affects young children whose diet is high in starch and low in protein
- especially in underdeveloped countries, but also high consumption of processed, energy-dense but micronutrient poor food
- resulting chronic diseases e.g. obesity, diabetes (so also prevalent in industrial countries)
Iodine
- needed for synthesis of hormone thyroxine (regulates metabolic rate)
- in most seafood/ some vegetables
- lack of: swelling thyroid gland (goitre); in children, largest cause of preventable mental retardation
- solution: add to salt (low cost)
Vitamin A (retinol)
- needed for healthy skin (acne treatment), good eyesight, protection against some damaging effects of toxins (anti-oxidants)
- orange and yellow fruits/vegetables, spinach, egg yolks
- lack of: xerophthalmia (dry eyes and night blindness)
- solution: fat-soluble, so its added to margarine (Vitamin A fortification); inexpensive, has reduced levels of xero. in many parts of the world; possibly rice for Vitamin A fortification
Iron
- most prevalent micronutrient deficiency
- essential for hemoglobin (which is responsible for blood transporting oxygen around the body)
- lack of: anemia, symptoms include fatigue, brittle nails, poor endurance and lowered immunity
- source: red meat, green leafy veg, nuts and seeds
- solution: iron supplementation may increase susceptibility to malaria (also widespread)
- iron fortification best when added with vitamin C to cereal flour and milk products.
Other micronutrient deficiencies and diseases
Niacin (Vitamin B3)
- Pellagra: dermatitis, diarrhea, dementia
Thiamin (Vitamin B1)
- Beriberi: weight loss, fatigue, swelling
Vitamin C
- Scurvy: bleeding gums, lowered resistance to infection and dark spots on skin
Vitamin D
- Rickets: softened, deformed bones
Selenium
- Kashin-Beak disease: atrophy and degeneration of cartilage (happens esp. in northern Russia and China, where the soil is Se deficient)
Macronutrient deficient
Protein
- when prolonged is life threatening
- Marasmus: mainly in infants from developing countries at the time of weaning; failure to gain weight, then weight loss and emaciation (weak and thin)
- Kwahiorkor: similar to Marasmus, affects young children whose diet is high in starch and low in protein
SUMMARY
Micronutrient
deficiencies include:
•
iron—anemia
•
iodine—goitre
•
retinol (vitamin A)—xerophthalmia, night
blindness
•
niacin (vitamin B3)—pellagra
•
thiamin (vitamin B1)—beriberi
•
ascorbic acid (vitamin C)—scurvy
•
calciferol (vitamin D)—rickets.
Macronutrient
deficiencies include:
•
protein—marasmus and kwashiorkor.
Some
causes of malnutrition may be discussed
here.
Solutions
include:
•
providing food rations that are composed of
fresh
and vitamin- and mineral-rich foods
•
adding nutrients missing in commonly
consumed
foods
•
genetic modification of food
•
providing nutritional supplements
•
providing selenium supplements to people
eating foods
grown in selenium-poor soil.
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