Zinc is a hugely important, though lesser-known, mineral in our diets. It is essential for the function of many enzymes which catalyse biological reactions in our bodies. It is also crucial to our immune system, critical for reproductive health and assists in efficient wound healing.

Daily recommended amounts (US) are 11mg for men and 8mg for women (12mg when breastfeeding). The elderly, children, vegetarians, alcoholics and low-income groups are more vulnerable.

If you find yourself living in rural China, eating a local diet for any length of time, it is worth being more zinc-aware. Reliance on plant-based foods has resulted in up to 25 percent of some population groups being deficient in certain areas.

On the whole, animal proteins are better zinc-providers. For those feeling lavish oysters are the best option, indeed the common perception of oysters as an aphrodisiac may relate to their high zinc content given its role in reproduction. Half a dozen Eastern oysters contain a whopping 85mg. Red meat is another good option - a 200g sirloin steak contains around 10mg; with the same amount of pork tenderloin containing 4mg. A decent-sized carp fillet, contains 3.5mg. Dairy foods also contribute, with a cup of yogurt containing 1.5mg, and a glass of milk around 1mg.

Vegetarian zinc sources include nuts, seeds, whole grains and breakfast cereals. Cereals are usually fortified and their zinc content outlined in the nutrition panel on the box. Two tablespoons of pumpkin seeds contain 2.5mg of zinc and a handful of almonds, 1 mg. Soybeans are a good seasonal option, and are delicious boiled in the pod, lightly salted and eaten as a snack. A cup of beans (without pod) provides 2.5mg.

The higher the protein intake in the overall diet, the more zinc is absorbed. This applies not only to animal protein but also to that from vegetarian sources.

Early signs of actual zinc deficiency are a muted sense of taste, poor immune reactions and skin problems. Other symptoms include hair loss, diarrhea, delayed sexual maturation and impotence, eye and skin lesions, and loss of appetite. These symptoms are quite generalized so it is important to see a doctor to diagnose your symptoms.

This nutrition-related column is written by Nina Lenton, a qualified dietitian living in Beijing and working at Bayley and Jackson Medical Center. Contact her at nina.lenton@bjhealthcare.com.

(China Daily 08/10/2007 page14)