Is broccoli a nutritional showstopper?

Abused by canteen cooks everywhere, the much maligned broccoli has had a makeover in recent years.

From school dinner mulch, broccoli has been reinvented as a tenderstem, purple sprouting nutritional showstopper.

"Broc" fans claim this Sunday staple can help combat cancer, high blood pressure, cardiovascular disease and diabetes.

Broccoli is a good source of vitamin C and folate (naturally occurring folic acid). It also contains vitamins A, K, calcium, fibre, beta-carotene and other antioxidants (notably indole-3-carbinol and sulforaphane).

We've teamed up with the British Dietetic Association (BDA) to see if the many health claims made about broccoli stand up to closer scrutiny.

The evidence on broccoli?

Can eating broccoli prevent cancer?

Eating more non-starchy vegetables, such as broccoli, is associated with a reduced risk of some cancers (including mouth, throat and stomach cancers), according to a good quality 2007 review (PDF, 1.8Mb) of the evidence on cancer prevention by the World Cancer Research Fund. It is possible that some of the compounds in broccoli may have health benefits, but clinical trials are needed to investigate this further.

Does broccoli reduce high blood pressure?

There is no evidence to suggest broccoli can help lower blood pressure. In a 2010 study, 40 patients with high blood pressure who ate 10g of dried enriched broccoli sprouts for four weeks saw no improvement to the health of their blood vessels and did not reduce their risk of atherosclerosis (narrowing of the arteries).

Can broccoli help prevent cardiovascular disease?

In a small study from 2012 of 81 people with diabetes, those in a group that ate 10g a day of enriched broccoli sprouts powder for four weeks saw a reduction in their levels of cholesterol and triglycerides (a type of fat found in the blood), both of which can cause cardiovascular disease.

Does broccoli help in diabetes?

In a lab study from 2008, researchers applied the antioxidant sulforaphane to human blood vessels incubated with sugar. They found that sulforaphane appeared to prevent the damage to small blood vessels caused by high blood sugar (which can happen if you have diabetes). However, it is unclear from this study whether sulforaphane would protect a person with diabetes from damage.

The dietitian's verdict on broccoli

Alison Hornby, a dietitian and BDA spokesperson, says: "Broccoli may not live up to the hype, but nevertheless it contains many nutrients, such as folate, soluble and insoluble fibre, vitamins C and A, and calcium, which are needed for numerous functions in the body.

"It is a member of the family of cruciferous vegetables along with cauliflower, bok choy and cabbage. These all contain compounds that are linked to improving the body's ability to impede the growth of cancer cells.

"Broccoli is a flexible vegetable that works well in salads, stir fries, curries and soups. An 80g serving will count towards your 5 A Day."