Dr John Briffa: I can't believe in no butter

For as long as I can remember, a debate has raged over the relative merits of butter and margarine. Food purists contend, as far as flavour is concerned, that butter wins hands down. But doctors and dietitians have been quick to point out that butter is rich in artery-clogging saturated fat, which puts it firmly in a nutritional no-go area. At the same time, slick advertising campaigns have been extolling the virtues of margarine's cholesterol-reducing and heart-healthy effects. However, despite margarine's apparent pedigree, I have for a long time had difficulty reconciling how a heavily processed, chemicalised food could really have a healthy edge over what is essentially a natural and untainted one.

Most margarines are made of vegetable oils treated in a way which forms chemical entities known as trans fatty acids (also known as partially hydrogenated fats). These are essentially damaged fats, the like of which have only been seen in the human diet in appreciable quantities over the last half-century. Research increasingly suggests that trans fatty acids actually increase the risk of heart disease, and perhaps other conditions, including cancer. Increasing concerns about 'trans fats' have led some margarine manufacturers to look for alternative ingredients. As a result, some spreads are now based on what is known as 'interesterified' fats. Essentially fats that have been chopped up chemically and re-assembled, their long-term effect remains unknown. But personally, I'm nervous about eating any food that is fundamentally new to the human diet.

In recent times, margarine manufacturers have also been lacing their products with plant-based substances known as stanols and sterols. These help block the absorption of cholesterol in the gut, and can therefore help reduce cholesterol levels in the blood. But though the admen are keen to shove this fact down our throats, it seems that cholesterol reduction is not the panacea we've been led to believe it is. While drug therapy for high cholesterol may have significant benefits, not one study has found that taking dietary steps to lower cholesterol has brought a reduction in overall risk of death.

Meanwhile, butter's predominant fat is saturated, and saturated fats, we are told, can only help speed our demise through heart disease. However, a close look at the scientific literature fails to bear this out. Many studies show no relationship between saturated fat intake and heart disease. And no research into reducing saturated fat in the diet has found that it reduces funeral rates. So despite its bad press, the evidence reveals that the saturated fat on which butter is based is not nearly the dietary spectre it's made out to be. To my mind, the science suggests what our taste buds knew all along: butter really is better.

Nutrition news

Over the last decade scientists have become interested in the effect of phytoestrogens on the risk of breast cancer. These plant substances act similarly to, and are known to block the action of, the hormone oestrogen in the body. As many cases of breast cancer are believed to be related to stimulation of breast tissue by oestrogen, this has led to the theory that phytoestrogens might reduce the risk of breast cancer. As soya products such as soya milk and tofu are particularly rich in them, they are often recommended as part of a breast cancer prevention package.

However, some scientists claim that the oestrogen-like activity of phytoestrogens in soya might actually increase breast cancer risk. To settle this argument, researchers have recently examined eight studies into the association between soya and breast cancer risk. Five of these found soya intake to be associated with a reduced risk of breast cancer, while the other three showed no effect. Clearly, the bulk of the evidence supports the idea that soya products may offer some protection against breast cancer.

Dear John

I have been suffering from splits at the sides of my mouth on and off for a year or so. Do you know of anything that might help?
Bernard Bristow, Chichester

The medical name for cracking at the corners of the mouth is angular stomatitis. This condition is often painful, and can make talking and eating quite uncomfortable. In my experience, it is often related to nutritional deficiency, particularly in the mineral iron. While iron deficiency is relatively uncommon in men, it may still be worthwhile having this checked out by your doctor. The best test to determine how much iron you have in your body is to measure what is known as your serum ferritin level.

If this is low, then iron supplementation may help resolve your symptoms.

Another nutritional factor which is common in angular stomatitis is a deficiency in the B group vitamins, particularly vitamins B2 and B6. I would advise you to eat more foods which are rich in iron, B2 and B6, including wholemeal bread, green leafy vegetables, eggs, fish and meat. In addition, take a B complex supplement each day containing 25-50mg of the major B vitamins B1 to B6.

This will almost certainly clear your problem up within a few weeks.

· If you have any issues you would like Dr John Briffa to address in this column, please contact him by email on john.briffa@observer.co.uk. Please note that Dr Briffa cannot enter into any personal correspondence.

Thanks to guardian.co.uk who have provided this article. View the original here.