Iron is particularly important for menstruating and pregnant women, also for vegetarians and vegans. It is a component of blood cells which, among many other uses, transports oxygen from lungs to the rest of the body. Hence, low iron levels may result in fatigue as well as reduced immunity and anaemia.

Food sources include:
Meat, especially red meat e.g. beef, lamb, and ostrich.

Plant sources of iron are poorly absorbed in comparison to animal sources, vitamin C aids absorption,  vegetarians and vegans will need to increase:
Spirulina and chlorella
Pumpkin seeds
Dark green leafy vegetables