A1.8~A1.14

Difference between Minerals and Vitamins

Minerals ： inorganic elements in ionic form – e.g. sodium (Na⁺), potassium (K⁺) and iodine (I^–)

Vitamins: organic compounds made by plants or animals – e.g. retinol (vitamin A) and calciferol (vitamin D)

How do we determine the recommended daily intake of vitamin C ?

Retrospective Research:

Ä An older method used was to: identify sufferers of vitamin C diseases and determine their levels of vitamin C.

Ä Unfortunately, this was an inexact method for determining dietary requirements as it was based on preventing disease, not promoting any further more cellular functions.

Clinical Trials:

Ä More recent attempts at determining the recommended daily intake of vitamin have involved through experimental studies

Ä This has included testing cell cultures, guinea pigs and finally humans.  

Ä The purpose of these tests are to identify cellular function and disease onset at different daily amount of vitamin C

How much vitamin C does an adult need to consume per day?

Higher intake gives protection against upper respiratory tract infections, and the danger of rebound malnutrition

Common sources of vitamin C: fruits, orange juice and vitamin C tablets

The recommended daily allowance (RDA) of vitamin C will be different between gender and age

The recommended daily intake (RDI) of vitamin C has been set at 65 – 90 mg

However, there is significant debate as to whether the daily intake should be higher (> 1000 mg), in order to achieve beneficial effects.

Some claim that higher doses of Vitamin C may boost the immune system, speed recovery from injury and protect against upper respiratory tract infections

Others suggest that taking larger doses would promote rebound malnutrition: the body changes to a larger intake and responds poorly whenever dosages drop back to normal levels

Vitamin D in human diets:

Cereal (fortified)

Oily fish (e.g. tuna)

Milk (fortified)

Egg (specifically yolk)

Liver

Yogurt

Balancing the risks from sunlight:

Ä UV light causes the skin to synthesize vitamin D, where it is stored in the liver for when UV levels are low

Ä Insufficient sun exposure may lead to skeletal deformities

Ä However high levels of UV light can damage skin cells and cause skin cancers

Ä Using sun block and covering skin with clothing will prevent UV radiation reaching the skin, inhibiting vitamin D production

Ä Certain diets (e.g. vegans, vegetarians) are lack of vitamin D, so that such people need more exposure to sunlight

Ä Individuals with darker skin pigmentation produce vitamin D more slowly, but protected the skin better

Ä Some people may be at a greater risk of vitamin D deficiency due to cultural or religious practices

Ä Having vitamin D in the diet can reduce the risk of vitamin D deficiency without requiring sun exposure

Vitamin D Deficiency Causing Rickets

A.1.13  The benefits of artificial dietary supplementation to prevent malnutrition

Ä Artificial supplementation ensures a group of people has sufficient access to essential nutrients, even when the natural dietary supply may be limited

Ä Iodine is necessary for thyroxine production and an iodine deficiency will enlarged thyroid and mental retardation

Ä Dietary supplementation is usually achieved through the production of iodised salt, as few foods are rich in iodine (like seafoods)

A.1.14  The importance of fibre

Dietary fibre is an important part of a balanced diet as it plays an important role in human health:

Ä It provides bulk in food, ensuring the continuous passage of materials through the digestive tract

Ä Stimulates peristaltic contractions to make the digestive system to pass food

Ä Helps regulate blood sugar and reduces blood cholesterol

Ä Lowers risk of appendicitis and intestinal cancer

Ä Helps prevent constipation