The increasing popularity of cosmetic surgery in the UK and of body make-over shows on TV point to our increasing preoccupation in allaying the visible signs of ageing. My experience is that there is considerable interest in approaches that might ward off the internal effects of the ageing process, too.

I quite commonly see individuals in practice who complain that they are not as mentally sharp as they used to be. Some fear their loss of mental edge may represent the first steps on the road to a brain-drain condition, such as Alzheimer's.

There has been considerable interest recently in the potential part played in brain-function deterioration by the substance homocysteine. Excesses of this natural blood constituent appear to have the capacity to damage the lining of the arteries and predispose to atherosclerosis - the process responsible for the gradual furring up of our arteries that is common in ageing. Atherosclerosis may end up compromising blood supply to the brain and is a recognised risk factor for diminishing brain function and dementia in later life.

Studies have found that high blood levels of homocysteine are associated with an increased risk of dementia. One study, published in this month's American Journal of Clinical Nutrition, discovered that high homocysteine levels were linked with increased risk of Alzheimer's, even in individuals unaffected by compromise to the blood supply to their brains. This finding suggests that in addition to increasing the risk that the brain will be starved of blood, homocysteine may be toxic to brain tissue as well.

Scientists have now started to put forward the idea that quelling homocysteine levels may help to preserve brain function. Nutrients known to help reduce levels of homocysteine include folate, vitamin B12 and vitamin B6. Interestingly, the recent AJCN study found that low levels of folate were found to be a risk factor in Alzheimer's. Also, another study in the journal found that a low level in any of the nutrients folate, B12 or B6 appeared to increase the risk of general brain function decline.

Foods rich in folate include oranges and green leafy vegetables. Vitamin B6 can be found in liver, avocado, bananas and fish, and B12 in meat, fish and eggs. I'd also recommend supplementing with 800-1,000mcg of folic acid, 10mg of vitamin B6 and 400mcg of vitamin B12 each day. For those keen to do what they can to preserve brain function, ensuring a good intake of these nutrients is certainly worth thinking about.

Dear John

I suffer from heat or even 'burning' in my feet. It's not too bad in the day, but can be very uncomfortable at night. My GP can find nothing wrong, but has suggested that I take a low-dose antidepressant at night to help ease my symptoms. I may try this, but would like to try something more natural first. What might help?
BD

'Burning feet syndrome' can be puzzling - although the symptoms can be very severe, usually there are no abnormalities to find with regard to the circulation or nerve supply to the feet. My experience is that this is very often related to a deficiency of vitamin B5 (pantothenic acid). What's more, I find that higher intakes of this nutrient almost always relieve this symptom within a few weeks. To begin with, increase your consumption of nuts, which are rich in vitamin B5. However, to get really useful quantities of nutrient, start by taking 250mg of vitamin B5 twice a day until your symptoms subside. After this, take a B complex supplement with at least 20mg of vitamin B5. This should help prevent any recurrence of your uncomfortable symptoms.

· If you have any issues you would like Dr Briffa to address in his column, please email him on john.briffa@observer.co.uk. Please note that Dr Briffa cannot enter into any correspondence. You can also visit www.drbriffa.com. Before following any recommendations in this column, you should consult your own medical adviser about any medical problems or special health conditions

Nutrition news

The omega-3 fats that are found in oily fish, such as salmon, trout, mackerel and sardines, have a number of potentially beneficial effects in the body, including an ability to reduce the risk of cardiovascular-related problems, such as heart disease and heart attacks. Recently, researchers in Edinburgh assessed whether fish-oil supplementation might be of benefit to individuals undergoing coronary artery bypass grafting. This procedure, though usually effective in improving blood supply to the heart muscle, is also known to have the potential to damage the heart muscle around the time of the operation. In this study, published in the journal Prostaglandins, Leukotrienes and Essential Fatty Acids, individuals were treated with 8g of fish oil or placebo (inactive medication) each day for six weeks prior to surgery.

Individuals in the study had the extent of heart-muscle damage assessed through measurement of a substance known as troponin 1 (higher levels of which signify damage to the heart muscle). One day after surgery, troponin 1 levels were found to be significantly lower in the fish oil-treated group compared with those taking the placebo.