In this area, the fat is likely to be the much touted Omega-3, which could improve the woman’s own mental abilities as well as those of her child during pregnancy.

Men respond to the double enticement of both an intelligent partner and an intelligent child, the researchers at the Universities of Pittsburgh and California said.

The findings appear to be borne out in the educational attainments of at least one of the UK’s most famous curvaceous women, Nigella Lawson, who graduated from Oxford.

But experts are not convinced by the findings.

"On the fatty deposits being related to intelligence front, it’s very hard to detangle that from other factors, such as social class, for instance, or diet," said Martin Tovee of Newcastle University.

"And much as we logically like the idea that men are interested in the waist to hip ratio, it actually features relatively low down the list of feature males look for in a potential partner."

Previous research has shown quercetin is metabolised very quickly by the intestine and liver and is not actually found in human blood.

So instead the researchers concentrated on the compounds that enter the bloodstream after quercetin is ingested, absorbed and metabolised.

The compounds were used - in concentrations similar to those that would be produced following digestion - to treat cells taken from the lining of the blood vessels.

Lower dose, bigger impact

Lead researcher Dr Paul Kroon said: "We tested compounds that are actually found in the blood, rather than the flavonoid in food before it is eaten, as only these compounds will actually come into contact with human tissues and have an effect on arterial health.

"The effect is more subtle than laboratory experiments using the parent compound.

"But the metabolites still have an effect on the cells lining the blood vessels."

The research found that, in the case of one inflammatory process, a lower dose of the compounds - achievable by eating 100g to 200g of onions - actually had a bigger impact.

Bridget Aisbitt, a nutrition scientist at the British Nutrition Foundation, said: "Inflammation is an important process in the furring up of arteries that can lead to heart disease and stroke and this study gives us clues as to why a diet rich in fruit and vegetables appears to reduce the risk of these conditions.

"In the UK we are only consuming about two portions of fruit and vegetables per day on average, so this study underlines the importance of getting your five a day to stay healthy throughout life."

One obesity expert said fatty liver in today’s children was "a tragedy of the future".

Fatty liver is exactly as it sounds - a build-up over time of fat deposits around the organ.

At the time, no ill-effects are felt, but it has been linked with a higher risk of potentially fatal liver failure later in life.

The study, carried out at Boston Children’s Hospital, looked at the effect of diets with precisely the same calorific content, but very different ingredients when measured using the glycaemic index (GI).

This is a measure of how quickly the energy in the food is absorbed by the body, producing a rise in blood sugar levels - high GI foods lead to sharper rises in blood sugar, and similar rises in insulin levels, as the body releases the chemical in response.

High GI foods include many breakfast cereals and processed foods such as white bread and white rice.

Low GI foods include unprocessed fruit, nuts, pulses and grains, including rye or granary bread, spaghetti, apples and oranges.

Silent and deadly

After six months on the diet, the mice weighed the same, but those on the high GI diet had twice the normal amount of fat in their bodies, blood and livers.

The researchers say that because the processed carbohydrates are absorbed so quickly, they trigger the release of more of the chemical insulin, which tells the body to lay down more fat.

Dr David Ludwig, who led the research, said that the results would also apply to humans, and even children, in whom fatty liver is becoming far more common.

Between a quarter and half of all overweight American children are thought to have the condition, he said.

"This is a silent but dangerous epidemic," he said.

"Just as type 2 diabetes exploded into our consciousness in the 1990s, so we think fatty liver will in the coming decade."

Insulin resistance

Tam Fry, National Obesity Forum board member and chairman of the Child Growth Foundation, said it was clear that eating a diet rich in high-glycaemic food led to increased fat.

He said: "Fatty liver is going to be one of the tragedies of the future unless we do something about it."

Azmina Govindja, a dietician and spokesman for the British Dietetic Association, said that the biggest threat from a diet rich in high-glycaemic food was development of insulin resistance - the first sign of type 2 diabetes.

She said: "There is a place for high-glycaemic carbohydrates in moderation as part of a balanced diet, but there’s good research that eating too much can increase the risk of insulin resistance - and this can lead to serious health problems.

"However, this study is interesting, as there is other evidence that people who eat a diet rich in high-glycaemic food are more likely to have more body fat."

The questionnaires revealed men were less discriminating when it came to deciding who to kiss or who to have sex with.

They were more willing to have sex with someone without kissing, to have sex with someone they are not attracted to and agree to have sex with someone they considered to be a bad kisser.

But kissing was more important as a bonding mechanism to women.

In long-term relationships females not only rate kissing as more important than men, but they indicated that kissing was important throughout a relationship.

Meanwhile, men placed less importance on kissing as the relationship progresses.

There was also a difference in the sort of kisses the two sexes preferred, with men liking wet, tongue kisses.

Lead researcher Dr Gordon Gallup said kissing had developed over time to become an essential part of the courtship process.

But he added: "While both sexes participate in the adaptive benefits of kissing, we found sex differences when considering the pursuit of short- versus long-term mating strategies."

Dr Glenn Wilson, an expert in relationships at London’s Institute of Psychiatry, said: "Kissing is used by everyone as a bonding and testing mechanism.

"But the fact is women are more discriminatory than men. Men can just go out and spread their seed, but women have to take more responsibility because of the consequences and so they are likely to want to test more."

This is one of the few studies that have tried to spot differences between the likes of males and females.

The Newcastle team, led by Dr Anya Hurlbert, tested more than 200 men and women in their 20s, asking them to choose between colours on the computer screen.

Women were far more likely to choose blue shades with more red mixed in, and more likely to reject more green and yellow hues.

Nature or nurture?

One of the problems facing the researchers was to work out if this reaction is the product of years of British "blue for a boy, pink for a girl" culture.

To do this, the group tested were a mixture of white British and Chinese volunteers.

While the Chinese volunteers, male and female, also tended to favour red shades, not surprisingly since red is a "lucky" colour in China, the difference between men and women persisted.

According to the researchers, this strengthened the idea that the preferences might be based in biology, rather than culture.

Dr Hurlbert said: "Evolution may have driven females to prefer reddish colours - reddish fruits, healthy, reddish faces.

"Culture may exploit and compound this natural female preference."

Depression and colour

Yazhu Ling, another researcher working on the project, said that work was planned in younger children to confirm the finding.

She said that she expected other projects to investigate links between colour preference and weight, and depression.

No clear explanation exists as to why all humans might also have an underlying liking for blue.

Dr Hurlbert speculated: "Going back to our ’savannah’ days, we would have a natural preference for a clear blue sky, because it signalled good weather.

"Clear blue also signals a good water source."

In some experiments, the researchers from Ohio State University saw cancer growth not just slowed, but as many as 20% of the cells killed.

For instance, anthocyanin pigments obtained from black carrots and radishes slowed the growth of cancer cells by between 50 to 80%.

But compounds from chokeberries for instance killed up to a fifth of existing cells, without impacting upon healthy ones.

Working it out

The researchers say their findings bring the scientific community closer to understanding what it is that gives fruit and vegetable their much touted cancer-fighting properties.

"These foods contain many compounds, and we’re just starting to figure out what they are and which ones provide the most health benefits," said Monica Giusti, the lead author of the study.

She suggested that the results from this particular study suggested that anthocyanin may be of particular use in fighting gastrointestinal cancers.

Very little of the substance is absorbed by the bloodstream, but it may be absorbed in the gastrointestinal tract as it passes through, she said.

However, the researchers stopped short of recommending one particular fruit and vegetable over another, stressing that more research was needed into how these compounds worked.

Henry Scowcroft, senior information officer at Cancer Research UK, said: "Although at an early stage, this research helps us understand exactly how the substances in fruit and veg protect us from bowel cancer.

"Isolating these substances - and tweaking them so that they’re even more potent - could allow scientists to develop new drugs to treat the disease.

"In the future, it could lead to the development of drugs that help prevent bowel cancer in people at high risk."