Nutritional science seems to churn out a perennial crop of research demonstrating the health benefits of consuming a decent daily quota of vegetables, especially the brassica class, such as broccoli, cabbage and cauliflower. Research suggests that one specific constituent of brassica vegetables, indole-3-carbinol, has some capacity to protect against several types of cancer, including those of the breast and prostate. In a very recent study, indole-3-carbinol was also found to have the ability to inhibit the herpes simplex virus - the organism that causes cold sores.

Once contracted, the herpes virus lies dormant in the body, where it is normally kept in check by the immune system. However, in certain circumstances, such as when we are run-down and our immune system is weakened, the herpes virus can enjoy a resurgence and erupt on to the surface of the skin in the form of a cold sore.

The replication of the herpes virus is aided and abetted by the amino acid arginine, two rich sources of which are chocolate and peanuts. Chocolate peanuts would seem to be one food worth avoiding by those wishing to counter cold sores in the long term. While arginine tends to aggravate the herpes simplex virus, another amino acid, lysine, has the opposite effect. Like indole-3-carbinol, lysine inhibits the herpes virus and works by helping to scupper its attempts to replicate in the body. While eating foods rich in lysine (such as bananas) has the theoretical capacity to help prevent cold sores, a more aggressive approach tends to work better in practice. Taking 1,000mg of lysine in supplement form each day often proves effective in reducing the risk of cold-sore outbreaks. However, a larger dose is generally called for, should signs of an eruption - such as discomfort, numbness or tingling in the skin - threaten. Taking 1g of lysine three times a day for a few days at the first signs of trouble can often stop an attack in its tracks.

Even if a cold sore has established itself, lysine may still offer relief, as supplementation with this nutrient also appears to reduce the severity of cold sores and speed their resolution.

Another natural agent that tends to work well alongside lysine is vitamin C, which has both immune-stimulating and antiviral properties. A daily dose of 1g of vitamin C is a useful prophylactic, though upping this to a three-times-a-day dose is recommended if a full-blown cold sore or impending symptoms are in evidence.

For topical relief, those afflicted with cold sores may like to use creams or ointments containing aloe vera or propolis (a natural antimicrobial agent extracted from beehives). Both these substances have been found to help reduce the discomfort of cold sores and hasten their healing.

For cold-sore sufferers, experience shows that natural remedies offer a great deal in the way of lip service.