Dr Stuttaford’s replies cannot apply to individual cases and should be taken in a general context. Please consult your GP if you suffer from any health or special conditions.

It is very important when patients are depressed, and therefore usually have a very poor appetite, that they don’t suffer vitamin and mineral lack. I would, therefore, suggest one of the multivitamin and mineral supplements. There are a large number on the market and they are all much of a muchness.

I’m glad to hear that your sister is taking antidepressants. These have been one of the great revolutionary introductions to medicine in the last 50 years. It is important to remember that it is necessary to take them for some months, and after this time they must be tailed off very slowly. Some depressed patients, only a small but still appreciable minority, may need to take antidepressants for many years. This doesn’t mean that they are addicted to them. I mention this, as there was a very, I thought, one-sided exposition of antidepressants on Panorama on Sunday.

Since reading Barry Groves’s Eat Fat Get Thin and the Montignac method, I have been following a low-carbohydrate diet for the last four months. My diet consists of meat, vegetables, fruit and dairy products, with very little or no bread, rice, pasta and cereals, and sugar only in the form of fructose. Although not overweight at the start, I have lost 4kg and feel very healthy and energetic (I am a 36-year-old female). What is your view of this type of “diet for life”'? Are there any health concerns I should be aware of, such as possible high cholesterol (I eat plenty of full-fat milk products, yoghurt, cheese, eggs, etc)? Should I also be taking a vitamin supplement? Name and address withheld

A balanced diet is ideal. We must all remember that when diabetic patients were treated with a very low carbohydrate diet, and derived most of their energy from fats, they suffered in time from a larger increase in cardiovascular disease than could be explained by their diabetic state. I would have thought, and I think the Montignac diet would agree, that rice, pasta, beans and peas would be an ideal addition to your diet. Fructose is a very refined sugar and so does have some disadvantages.

I certainly think that you should have your cholesterol measured regularly, and should pay particular attention to your low density lipoprotein cholesterol (the LDL), as this is the sinister blood fat which can cause cardiovascular diseases. Congratulations on losing the weight. Now perhaps the time has come to return to a more standard balanced diet.

While the recommended doses of the most common of vitamins such C, B and A vary from country to country, is there a common maximum amount? Also, what are the dangers and symptoms of taking too large a dose of any of them? David Gregg, Glasgow

This is a very good question. There is a wide variety of opinion about the maximum levels of vitamins and minerals which should be taken. There isn’t a common agreement about the maximun amount that is considered safe. In this country, many of our recommended daily intakes of both vitamins and minerals was determined during the war at the time of rationing, and has never been adequately reassessed. If we take, for instance, one of the vitamins you mention - vitamin B6 - we see that the recommended daily intake varies from 2mg in the US to 1.4mg in the UK and 1.5mg in Europe.

I’m a believer in vitamin supplements myself, as I think so many people have inadequate diets because they live a rushed life, with no time to have the standard traditional meals. There is no doubt that a well-balanced menu containing organic foods freshly harvested from your own garden is an ideal way of life. As it is, most of us live in cities, the vegetables on the costermonger’s barrow or even on the shelves of the best shops are days old before we eat them, and the vitamin content has suffered accordingly.

You ask about toxicity. Vitamin C is interesting; once it reaches a certain threshold it is excreted by the kidneys but, even so, it can give rise to diarrhoea and abdominal pain if taken in excess. It is also said to encourage the formation of oxalate stones; it is unlikely that these form in the kidney, and this risk is probably more theoretical than real.

A few trials have shown that excessive doses of vitamin C, rather than improving life expectancy in people with cancers and heart diseases, may actually reduce it. Most people would say that 500mg a day is a wise upper limit. Others would recommend not more than a gram a day. Those who believe in megadoses of vitamin C will take many times this amount, and I have regularly seen patients who are doing this and swear that this is why they are still alive despite some dread disease.

Vitamin A is well known for being toxic when taken in excess. This is one of the classically known hazards of vitamin overindulgence. A regular intake of more than 7.5-9mg a day of vitamin A can cause headaches, nausea, loss of appetite, and loss of balance. There is evidence of liver damage and calcification in the soft tissues of the musculoskeletal system, as well as over-thickening of the long bones. The skin becomes excessively dry and the hair may even drop out. Too much vitamin A is certainly not to be recommended.