Biochemistry and nutrition
Biochemistry is the chemistry of life. Nutrition is how the body uses food. Biochemistry explains what happens to each nutrient inside the cell.
Two sciences, one goal
Nutritional biochemistry joins the two. It follows each nutrient from the plate to the cell.
How biochemistry helps nutrition
- Digestion and absorption: enzymes such as amylase, pepsin and lipase break food into small units the gut can absorb.
- Metabolism: shows how glucose, fatty acids and amino acids are broken down to give ATP (adenosine triphosphate, the cell's energy currency).
- Vitamins and minerals: B vitamins work as coenzymes (enzyme helpers); zinc, iron and magnesium act as cofactors.
- Deficiency diseases: explains why lack of a nutrient causes disease, e.g. thiamine and beriberi, niacin and pellagra.
- Diet therapy: gives the reason behind special diets in diabetes, phenylketonuria (PKU), lactose intolerance and heart disease.
- Nutritional assessment: blood glucose, haemoglobin, serum albumin and lipid profile are all biochemical tests.
Nutrition problems explained by biochemistry
| Problem | Biochemical reason |
|---|---|
| Beriberi | No thiamine, so no TPP for pyruvate dehydrogenase; glucose cannot be fully used for energy |
| Pellagra | Low niacin, so less NAD+ for the many oxidation reactions |
| Lactose intolerance | Low lactase enzyme in the gut, so milk sugar is not digested |
| Phenylketonuria (PKU) | Phenylalanine hydroxylase is missing; treated with a low-phenylalanine diet |
| Iron deficiency anaemia | Iron is needed for haemoglobin and for the cytochromes that make energy |
Every deficiency disease is a biochemical defect first. Low thiamine blocks energy release from glucose (beriberi), and low iron lowers haemoglobin and cytochromes (anaemia and tiredness). Biochemical tests often pick up a deficiency before clinical signs appear.
2 marks: “Define biochemistry.” Biochemistry is the study of the chemical constituents of living cells and the reactions they undergo. It is often called the chemistry of life.
5 marks: “Explain the relationship between biochemistry and nutrition.” Show how biochemistry explains digestion, metabolism, the coenzyme role of vitamins, deficiency diseases and diet therapy, with one example each.
Nutrition asks what we eat; biochemistry asks what happens to it inside the cell.