Option B.5 – Micronutrients and Macronutrients
B.5.1 – Outline the difference between micronutrients and macronutrients
Micronutrients
These are substances that are only required in very small amounts. They usually form co-factors of enzymes. Examples include vitamins and minerals (B, Co, Cr, Cu, F, Fe, I, Mn, Mo, Se, Zn)
Macronutrients
These are substances that are required in relatively large amounts for use within the body, including carbohydrates, fats, proteins and minerals (Ca, Cl, K, Mg, Na, P, S)
B.5.2 – Compare the structures of retinol (vitamin A), calciferol (vitamin D) and ascorbic acid (vitamin C)
Vitamins are soluble in either fat or water, depending on their structure. The fat-soluble ones will have long, non-polar hydrocarbon chains and are stored in fatty tissue in the body. Those that are water-soluble, on the other hand, tend to have hydrogen bonding due to a hydrogen atom attached to oxygen or nitrogen atoms. Since they are not able to be stored in fatty tissue, they must be consumed regularly to maintain a sufficient supply.
Retinol
Retinol is a fat soluble molecule due to the hydrocarbon chain and ring. The alcohol group does not have significant effect on the polarity, making it non-polar. It is important for vision at low light intensities.
Calciferol
This is fat soluble due to the non-polar hydrocarbon rings. It has a similar structure to cholesterol. It is important for stimulating the uptake of calcium ions into cells and the health of bones and teeth.
Ascorbic Acid
The alcohol groups are able to form hydrogen bonds, making the molecule water soluble. This forms a cofactor for many enzymes, helping with the repair of tissue after injury and resistance to diseases.
B.5.3 – Deduce whether a vitamin is water- or fat-soluble from its structure
Water soluble vitamins are polar molecules, with multiple -OH groups that can form hydrogen bonds.
Fat soluble vitamins are non-polar molecules, and are made up of hydrocarbon chains and rings.
B.5.4 – Discuss the causes and effects of nutrient deficiencies in different countries and suggest solutions
Malnutrition comes in two forms. The first is a lack of essential nutrients required for the functioning of the body. The second is when too much food is consumed that lacks nutrients, leading to obesity and related health issues. In both cases, the person lacks balance in their diet.
Iodine is used to synthesise the hormone thyroxine to regulate metabolism. When the body is deficient in iodine, the thyroid gland begins to swell, called goitre. It can also lead to mental retardation in children. These days, iodine is added to salt to increase consumption.
Vitamin A is important for healthy skin, good eyesight and protection from some toxins, since it acts as an antioxidant. When people are deficient, they have dry eyes and night blindness. Today, vitamin A is added to fatty products in the process of vitamin A fortification like margarine, as well as rice.
Iron is the part of the haemoglobin of red blood cells that binds to the oxygen and transports it to cells. Without it, the person experiences fatigue, brittle nails and lowered immunity. Iron supplements lead to susceptibility to malaria, so iron fortification is used instead. It is added with vitamin C to flour and milk products.
Insufficient macronutrients, such as proteins, can also lead to disease and death.
The key factors that contribute to malnutrition are:
- Distribution of global resources
- Nutrient-depleted soil and water
- Lack of education about health and diet
- Food processing
- Chemical treatments in food production
Malnutrition may be solved using the following methods:
- Eating fresh food that is rich in essential vitamins and minerals
- Adding micronutrients to commonly consumed foods through fortification
- Genetically modified food
- Providing nutrition supplements
- Labelling foods with the contents
- Education about eating well and having a balanced diet