The newspapers are so profoundly overrun with pseudoscience about food that there's no point in documenting it any longer.

They will continue with their Sisyphean task of dividing all the inanimate objects in the world into the ones that either cause or cure cancer, and I will sit at the sidelines, making that joke over and over again.

This week, however, the Telegraph, which has lost its science editor and its science correspondent in two months, deserves special attention, because two of its food stories went beyond stupid, and managed to give actively harmful information.

We'll start off with "Red wine could help prevent breast cancer". In fact it's even better than that. "Laboratory tests have shown that a chemical found in the skin of grapes could halt the development of most cases of the disease."

The story follows a standard template which they clearly now teach as valid in all journalism schools: a food contains a chemical, the chemical does something in a dish on a lab bench, therefore the food kills cancer in people. Or rather, red wine contains resveratrol: this chemical has been found to increase the activity of an enzyme called quinone reductase, which converts a derivative of oestrogen back to oestrogen, and that derivative can damage DNA, and damaging DNA causes mutations, and mutations cause cancer, so therefore, in the world of journalists, red wine prevents breast cancer in people.

This is a phenomena we might call "data mist": where someone gets one piece of research information lodged in their imagination and suddenly, for them, it explains the entirety of medicine.

Back in the real world there is the wine, and a whole human body. Red wine has a lot of stuff in it, including alcohol which, notably, is broken down into a chemical called acetaldehyde, and that itself causes DNA damage. Is there reason to think this might cause cancer, or would I be over-extrapolating myself?

Well. A huge number of observational studies have now been performed in real living humans, finding that people who drink more have more breast cancer. They have included careful analyses, in which they try to account perhaps imperfectly for other possible explanations for this relationship. These studies have even been collected together in a systematic review, and a meta-analysis, where all the figures are run onto one big spreadsheet, and they estimate that overall, half a glass of red wine a day increases your risk of breast cancer by 10%. If their figures are correct, alcohol causes about 6% of all breast cancer in the UK, meaning 2,500 cases a year.

So red wine, despite whatever it says on that press release you are holding in your hand, Kate Devlin, medical correspondent, does not prevent breast cancer.

Meanwhile they had "nutritional therapist Julia Fitzgerald" cheerfully informing Telegraph readers that "during the first four weeks of pregnancy taking a folic acid supplement (400 micrograms per day) can help prevent neural tube defects in the foetus such as spina bifida". You will remember that "nutritional therapist" is a term we can all legally use to describe ourselves, alongside "dilettante" "handsome" and "clown". Perhaps Fitzgerald's training in the field of "nutritional therapy" might have caused some confusion here, since folic acid for pregnant mothers is a rarity in their domain, being an intervention with an evidence base.

Sadly for Fitzgerald the evidence is not in her favour. And as all of the random women in their 30s I have asked today already knew, both Department of Health and NHS guidelines are identical, recommending very clearly that potential mothers should take a 400-microgram supplement from the time that they start trying for a baby, or from when contraception is stopped, up to and including the 12th week of pregnancy.

Perhaps Fitzgerald knows better. Perhaps she can also tell you the day you get fertilised. Perhaps this is the first time a nutritional therapist has ever recommended too few pills. And perhaps she will want to clarify her advice to 800,000 readers and their families which will increase their risk of delivering a baby with severe and disabling neural tube defects.

I will now go back to ignoring the nutritionists.

· Please send your bad science to ben@badscience.net