Fat-soluble vitamins: A, D, E and K
There are four fat-soluble vitamins: A, D, E and K. Because the body can store them, taking them in every single day is not essential.
| Vitamin | What it is for | Deficiency symptoms |
|---|---|---|
| A | Forming the visual pigments needed for sight · keeping the skin clear and healthy | Night blindness · Bitot's spots in the eye · dry skin · rough spots on the elbows and knees · respiratory illnesses |
| D | Controlling the absorption of calcium and phosphorus | Tooth decay · bone fractures in adults (osteoporosis) |
| E | Growth of tissues and cells | Premature births · faster breakdown of red blood cells · weakness in cell division · weaknesses related to reproduction |
| K | Forming the components needed for blood clotting | Delayed blood clotting |
Vitamin D and calcium
In section 1.6 you learned that calcium is needed for bone growth. But calcium is not absorbed without vitamin D. So even with enough calcium, a shortage of vitamin D leaves bones weak. It is a good example of how nutrients depend on each other.
Vitamin K and blood clotting
Calcium also matters for blood clotting. So healing a wound draws on vitamin K, calcium and vitamin C together.