biology

An ideal human diet contains Fats, proteins, carbohydrates, vitamins, minerals, water and fibre in correct proportions.

They are an energy source. Respiratory substrate oxidised to release energy for active transport, synthesis of macromolecules, cell division and muscle contraction. Digested in mouth and small intestines and is absorbed as glucose.

Rice, potatoes, wheat and other cereal grains.

They are an energy source, highly reduced and can be oxidised to release energy. Very important in cell membranes and as a componet of steriod hormones which are fat based. Digested in the small intestine and absorbed as fatty acids and glycerol.

They have no structure or function, but are essential in  small amounts to use other dietary components effiectly. Their absence results in deficiency diseases such as scurvy and rickets.

Known as roughage it is manily cellulose from plant cell walls. Found in vegetables and cereals. Provides enough energy so that there is no constipation.

Provides energy for the performance of metabolic work although the energy could be in any form.

1/7 fat, 1/7 protein, and 5/7 carbohydrates. 

They are building blocks for growth and repair of body tissue, as enzymes, as transport systems, as hormones and as antibbodies

Meat,fish and eggs.They must contain eight essential amino acids, since humans can not synthesis them. Digested in the stomach and absorbed as amino acids.

Marasmus or Kwashiorkor

Every chemical reaction in the body reguires water. A human needs 2-3 dm3 a day.

They have a range of specfic roles, and there absence may cause deficiency diseases such as poor growth, teeth and anaemia.

Diets rich in sugars

Damages tooth enamel and cause tooth decay.

Diets rich in saturated fats and cholesterol

Can cause heart disease. Fatty compouunds block up arteries which supple glucose and oxygen to heart muscle.

Diets in salt

Causes blood pressure to rise.

Diet low in dietary fibre

Causes constipation and cancer of colon.

Diets too high in energy content.

Causes obesity the extra mass and volume causes joint damage, increase of heart disease and circulatory diseases, increase diabetes, infections of the lungs as breathing becomes difficult.