Oysters are not only delicious, they're very light: only 70kcal per 100g (8 oysters).

Oysters are first and foremost an excellent source of minerals, mainly iron, which aids the absorption of oxygen, and zinc, which aids growth and repair of tissue. Copper aids the absorption of iron into your system and plays an important role in the production of tissue, fibres in the nervous system, the bones and skin pigmentation. Oysters also contain magnesium, potassium and calcium. 

Oysters are rich in Vitamin B12, which helps to regulate the level of red blood cells in the body, maintain balance in the nervous system and in the intestines, and is also rich in Vitamins A, C, E, D and B3. Oysters are reviving and refreshing, being rich in iodine.  

They're even rumoured to be an aphrodisiac...