In the second of our occasional series on academics and food, reproductive biologist Roger Gosden suggests a little healthy eating. John Davies reports. On his return from a day in London to his home outside Leeds, Roger Gosden called on a local supermarket. He bought a bottle of Italian red wine, some fresh basil, pine nuts, and pasta - which he proceeded to turn into a simple and quick dish for his wife and himself.

The dish that he served the day before we met was, as it happened, a good illustration of his "ideal diet" - one that would follow the eating habits of most Mediterranean countries. "There's a lot to be said for it on the basis of health," says Gosden, a professor in Leeds University's school of clinical medicine. "If I had to choose a particular type of diet for the rest of my life it would have to be Mediterranean.

"Polyunsaturated as opposed to animal fats, fresh fruit and vegetables - together with a combination of pulses and nuts - will give you a pretty well-balanced amino-acid pool. But it would have to be taken with a drop of wine to fully enjoy it, because all the evidence now suggests a modicum of alcohol is actually good for us."

Not that Roger Gosden is a nutritionist - his title is professor of reproductive biology, and his specialist areas include investigating the origins of birth defects such as Down's syndrome, and developing new techniques for in vitro fertilisation (IVF). Indeed, he has done enough at the frontiers of fertility to earn the adjective "controversial" - he had to stop work on one project that used genetic material from aborted foetuses because of a change in the law in 1994.

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Still, he has other breakthroughs to talk about. "We're ripening immature (human) eggs in vitro - taking eggs out of the ovaries early for fertilisation," he explains, "This doesn't require us to give hormones, so it would halve the cost of IVF treatment." His team has also been testing a form of "freeze-storing" ovarian tissue taken from young female cancer patients; radiation treatment can kill not only cancer tumours but also the egg-producing cells in their ovaries.

He has interests too at the other end of life: his book Cheating Time: Science, Sex and Ageing, published last year, looks at the ageing process and in particular the role of hormones such as oestrogen and testosterone. (Gosden worked for a period at the University of Southern California with Caleb Finch - "just about the best-known gerontologist in America").

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But is there some connection between such research interests and food? There is he says, "one interesting angle" - that if you put laboratory animals on a calorie-restricted diet, "they will live much longer and be much healthier than their litter mates who are on a cafeteria-type diet, feeding ad libitum. It seems the ageing process is slowed down. They have all the right minerals and proteins, it's just the number of calories that are reduced. What's more, with all their body system running on a slower time clock, the females' ovaries age more slowly, so they have the equivalent of the menopause later, too."

But it is "rather doubtful," he continues, whether these findings can be applied straightforwardly to humans. "I don't know anyone who is going on a low-calorie diet to get pregnant or to delay menopause."

Despite all that is known, Gosden admits that "we have yet to discover whether human fertility is affected by diet". He would like, however, to run a survey of the diets of people coming forward for IVF: "We might be able to say that certain people with certain conditions look as though they are deficient in certain vitamins ... so let's adjust their diet accordingly. In fact there's an old story about vitamin E being the fertility vitamin because if you put rats on a vitamin B-deficient diet they become reversibly sterile. That's not been proven in humans, but there might be a benefit from vitamin E. We now accept pills for pregnancy to boost nutritional deficiencies; so it's not implausible that to conceive it may be better to adjust your diet.

"Of course, our sister department here in Leeds, paediatrics, was the centre that discovered the role of folic acid in pregnancy." (Folic acid supplements are now regularly taken by pregnant women because they reduce the risk of their babies being born with spina bifida.) He is keen to stress, however, that vitamins are better in food, it seems, than taken in tablet form. "Human nutrition perhaps can't be reduced easily to so many grams of this, that and the other. It's very complex." Indeed, he describes the science of nutrition as "a bit of a Cinderella subject, although everyone's interested in it. Sir Peter Medawar once called it 'kitchen science', which I think is a nice expression. He was actually being disparaging, though, because we know so little about the chemistry of nutrition."

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Gosden in turn is gently disparaging about some nutritionists that he knows, who "don't follow the dictates of their lectures ... I've eaten in their homes and we've just eaten the same as Mr and Mrs Average. I think it's because they eat what their wives decide and what habit has dictated. Or possibly it's because they don't do the shopping that they don't have control over their diets."

In contrast, Gosden, who has two grown-up sons away at university, finds cooking at home a kind of relaxation. "It's fun making things in the kitchen," he says. "It's just like being in the laboratory." But surely he has enough of that in his working day? "If I did it all day long, it would be boring perhaps. But in my kind of work, you get to the stage where other people are doing the lab work and having the fun, and you're just telling them what to do and greasing the cogs."

Which brings us back to the previous evening's meal - one that took, Gosden estimates, little more than 20 minutes to prepare. As he lists the ingredients, he notes their medicinal properties - pine nuts, for instance, have valuable anti-oxidants, and sea salt is "good because it contains iodine. It's been estimated that about half a million people in the world are short on iodine, amazingly. There's iodine deficiency and goitre in Europe still."

As for the pasta, it can be any kind, says Gosden, but on that particular evening he chose farfalle: "With a sauce like that, there's a larger surface area to spread it on than if it's spaghetti. Perhaps it was a psychological choice - you know, the professorial bow tie."

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Roger Gosden's recipe forhome-made pesto. Two handfuls of fresh basil, chopped 3 or 4 cloves of garlic 2 spoonfuls of pine nuts Olive oil Sea salt freshly milled black pepper Using a mortar and pestle, grind thegarlic, then add the basil leaves andcontinue to grind until you have a green mush. Add the pine nuts and sea saltand grind some more, drizzling in the olive oil until it turns into a paste. Serve with your choice of pasta, allowing about3 oz per person, grinding the blackpepper on the pasta.