My sister-in-law was once a diabetic. She's not any more. This was not due to some miracle cure, but a common-sense change in her diet - she ate a lot more veg and a heap less sugar. The pounds dropped off, and she eventually reached the point where she no longer needed her insulin. While diabetes cannot be "cured", it can be sent into remission by a healthy diet. This is just one example of food-as-medicine, a subject that has interested me for almost as long as I've been cooking professionally.

A couple of months ago, I went to Westminster Kingsway College to observe a group of doctors learning to cook. They ranged from an elderly psychiatrist to a young, not-quite-qualified GP, all self-selected medics attending the first module of the first course of its kind in the UK. An Introduction to Culinary Medicine is led by a young GP called Rupy Aujla, author of the popular cookbook The Doctor's Kitchen, and whose aim is a relatively straightforward one: he is determined to get his fellow medics to realise that improving diet and lifestyle would help a lot of their patients. If only doctors knew how much medicine there is in the average supermarket vegetable rack, he says, we'd all be a lot better off.

This month, Bristol Medical School is running a full month's course, designed by Dr Aujla, on culinary medicine. It will include modules on weight management and portion control, fats, the "Mediterranean" diet, vegetarian diets, protein diets, paediatric and geriatric diets. It is a specialist option for third-year medics and will partner each student with a patient who will have some medical problem (perhaps obesity, kidney disease, an eating disorder, or high blood pressure). The students and patients will devise diets and recipes to help their conditions.

Although we largely seem to have forgotten this, nature provided a good deal of medication before we got hooked on pills.

Our great-grandmothers knew that fish was good for you, for instance. They didn't know why, and they'd never heard of omega-3s, the little miracle-worker found in oily fish, but they knew it was important. Today, we know more about why, but we don't always put this knowledge to use. Professor John Stein, of the Institute for Food, Brain and Behaviour, says our brains contain five grams of DHA, the long-chain omega-3 fat that "oils" the brain for rapid thinking. Another omega-3, EPA, also from fish, helps to reduce inflammation, which can lead to hardening of the arteries, high blood pressure and heart attacks. Omega-3 also reduces the chances of depression. For children, increasing intake of omega-3s can improve reading, and help those with ADHD and autism cope better.

And that's just fish, and just some of its health benefits. If we ate more fish, a lot of fruit and veg and whole foods, and a little good-quality protein, we'd be doing ourselves a favour. But there's still a long way to go.

Dr Aujla needs the buy-in of doctors or nurses, because they are the ones in touch with the patients, who can persuade them to give healthy eating a go. He's quick to admit that our already overstretched GPs are too busy to give personal cooking lessons to patients, or even to spend much time counselling them on diet. But his hope is that, by themselves becoming clued-up about nutrients and proficient in the kitchen, family doctors will be the catalysts for change in their patients' lifestyle.

It seems he is pushing at a half-open door: the Royal College of General Practitioners has already accredited four of his modules for inclusion among the optional courses doctors can take for their continuing professional development (CPD).

Culinary medicine is a discipline in its infancy in the UK, but in the US, it's far more well-established. The field was pioneered by Dr Tim Harlan at the Goldring Centre for Culinary Medicine at Tulane University, which was founded in 2012. Almost a quarter of medical schools now teach culinary medicine courses, where the 20 accredited modules include education around treating problems such as impaired renal function or congestive heart failure through diet. Dr Aujla is slowly adapting them all for the UK.

At the cooking session I witnessed, there was no shortage of enthusiasm. Lizzie, one of the participants, will join a Brighton practice in the autumn. She has already identified a community kitchen where she will organise cookery courses for her patients. Another participant could see the benefit for his diabetic patients and thinks he might persuade the local authority to support courses for them in the local college. A third told me how important this sort of relaxed, enjoyable intervention with food could be for his patients with eating disorders. "It would be like AA [Alcoholics Anonymous]," he said, "with patients becoming a mutual support group."

If reaction to this single course is anything to go by, it won't be hard to convince doctors to embrace culinary medicine as part of their CPD. Arguably, though, to make the biggest difference, the subject must be taught at medical school, as it is in the US, and as Bristol Medical School is trying this year.

With the ever-increasing demands on teaching time, squeezing in another course would be far from easy, even if the gains are obvious. But if doctors don't lead the way on this, then who will?