How can we know what is good for us?

The message was simple and succinct: eggs are good for you. But are they?

This month, a new study found that taking Hancock's advice and starting every day with an egg will increase the risk of heart disease by 18 per cent, and the risk of premature death from a stroke by 17 per cent.

Researchers for the Journal of the American Medical Association found that people with a dangerously high cholesterol levels more likely to have eggs – crucially with the yolks included – as a staple of their diet.

The debate about whether eggs are good or bad for your health has been running for almost as long as The Mousetrap, but it is just one of several conflicting reports about diets which leave many people scratching their heads about what they should and shouldn't eat.

Even the famed 'five a day' campaign has been thrown in to question, with officials some saying the advice is flawed, and other saying five is not nearly enough. It has been claimed that the five portions a day target was chosen mainly because it would be easy to market.

Lara Seago, a Stourbridge-based nutritional therapist, is sceptical about the latest findings on eggs. She says part of the confusion is down to the fact that different foods affect different people in different ways.

"It's just not as simple as saying eggs are bad for people because of the cholesterol," she says.

"For one thing, they are not now sure how strong the link between heart disease and cholesterol is any more.

"Each person is an individual, and you can't really give good advice without looking at the whole picture," she says.

"What is right for one person might not be right for another."

She says some things, such as deep-fried foods, are clearly not healthy, but in other cases the situation is much more nuanced.

"Chips are clearly not good for you, because of the saturated fat, and the way they are cooked which leads to carcinogenics, that's al bit of a no-brainer, but for things like eggs, and cholesterol, it is a lot more complex."

Over the years, there have been claims that dark chocolate, red wine, and even beer can bring health benefits. Back in 2000 there were even claims of pork scratchings being the latest diet fad to sweep California.

But usually, as is the case with eggs, no sooner has the ink dried on these reports then some other experts come along to shoot down the claims.

Very often, both sides of the argument have merits, and the question about whether something is good or bad for us depends on how much of it we consume, and how it fits in with other aspects of our lifestyle. The difficulty is, there is often a very fine line between healthy moderate consumption and harmful excess, and this may also vary from person to person.

For example, red wine contains resveratrol, a natural phenol found in the skin of grapes. A 2014 study found that resveratrol may prevent head and neck cancer, by killing damaged cells that can lead to the illness. Another study, published in 2014 in the Royal Society of Chemistry’s Food & Function, found that the more polyphenols, particularly resveratrol, in wine, the more the wine protects against colon cancer. A study of rats, by researchers at Texas A&M Health Science Centre College of Medicine, found that resveratrol may also help prevent age-related memory decline.

On the other hand, a 2012 study published in Alcohol and Alcoholism found that drinking wine could increase the risk of breast cancer. Cancer Research UK also warns that alcohol consumption increases the chances of developing mouth, throat, liver, and bowel cancer in some people. No wonder the public is confused.

A survey by the British Nutrition Foundation last year found that 43 per cent of adults said they found it difficult to find reliable information on healthy diets. Changing information, messages and advice from experts was identified as the biggest source of confusion, cited by 76 per cent.

The foundation's head of education Roy Ballam says: “With two thirds of adults overweight or obese, the UK is in the middle of an obesity crisis, and a lack of consumer knowledge and reliable information on healthy eating is a huge cause for concern.

"In the digital age, with growing concerns about the trustworthiness of information in the media, many are confused about which online sources are reliable, unsurprising when there is so much conflicting advice available.

"The public needs to receive more consistent messaging about diet and nutrition if we are to stand a fighting chance of changing these worrying health statistics."

Some of the reports obviously need to be taken with a pinch of (low sodium) salt. The pork scratchings claim was simply based on the fact that some Americans were eating them as a slightly healthier alternative to crisps, which is setting the bar pretty low to start with. And money, of course can often be a factor – it is always worth checking who is funding the research about the latest super food.

But one also has to remember that – as with other great bone of contention, global warming – that much of the science is still comparatively new. Half a century or so from now, today's ideas about what is good to eat may seem as antiquated as Hancock's Half Hour.

But that is little consolation for those of us trying to live a healthier lifestyle in the present.