Most of us know that our nails can tell us a lot about our state of health. But do we know how?

Charlotte Vohtz nails the subject in her book, Naturally Gorgeous, Essential Health and Beauty Secrets.

Here are eight tips from the book.

1. White spots or flecks on nails indicate a zinc deficiency, which may have many causes — too much alcohol or even side effects from taking the contraceptive pill.

2. Ridged or brittle nails may highlight a calcium deficiency or lack of vitamin A.

3. Cracked or broken nails — in the absence of any other reason such as heavy manual work — may show up a lack of fluids. Dehydration can cause many conditions including blocked sinuses.

4. Nails which split easily may indicate a lack of fatty acids in the diet.

5. Dryness and very rounded and curved ends could be a lack of vitamin B12, which may be linked to an iron deficiency.

6. For super-healthy nails make half your diet consist of fresh fruit and vegetables, some raw. This will boost your intake of vitamins, minerals and enzymes.

7. Add foods rich in sulphur and silicon, like fish, broccoli and onions. Also foods high in biotin, such as soya and whole grains.

8. Foods like wild seaweed (kelp tablets will do), which contain iodine for the thyroid gland, an organ that plays a part in the growth of nails, hair, skin and teeth.