They are common claims on the packets of mainstream foods and supplements that we buy every week: “lowers blood cholesterol; “supports immune system”; “promotes healthy joints”; “scientifically pro-ven”. But how true are they?

This week, the Advertising Standards Authority banned a TV advert that asserted that Actimel yogurt supported children’s natural defences against disease, because the evidence did not adequately support the claims. Now scientists working for the European Food Safety Authority (EFSA) have issued their judgment on more than 500 health claims made on the packets and in the advertising of 200 foods, food supplements and “healthy” food additives such as probiotics and omega oils.

Remarkably, only a third of the claimed health benefits of particular products could be backed up by sufficient scientific evidence, the scientists found. These were mainstream products, such as probiotics. But of 180 health claims for the benefits of probiotic ingredients, Europe’s food agency rejected every one; some because manufacturers couldn’t supply enough information about the “active” ingredient.

The findings have major reverberations for the food industry because they may force a change in the way that foods and supplements are marketed. Under EU law, all medical-sounding marketing claims relating to nutrition must now be verified, and brands whose claims are not approved will have to stop making the statements.

The British food and supplements industries are just beginning to plough through the detail of the EFSA findings, but know that they are going to have to fight their corner. “We’re obviously generally pleased with the favourable outcomes for vitamins and minerals,” says Sheila Kelly, executive director of the Proprietary Association of Great Britain, the food supplements trade body. “But the number of findings coming out at one time makes us uncomfortable, especially when EFSA is rejecting claims on the basis of not enough data. It raises the question of what data was looked at.”

It’s certainly true that these findings don’t necessarily mean that products don’t have the benefits they claim for some people — it’s just that they haven’t adequately proved it for the general population. But the consumer body Which? says it’s about time things changed. “Up until now, a company could make any health claim about a product, and it could only be removed if someone took them to Trading Standards,” says Sue Davies, of Which? “Now, products’ health claims will have to get approval before using the marketing.”

Here are some of the supplements and food additives that could soon have to change their messages:

Glucosamine

What is it?

Naturally occurring glucosamine is a building block for joint cartilage. Supplements of glucosamine, sometimes also containing chondroitin (another component of cartilage) are bestsellers.

Common claims

“Stimulates the growth of cartilage”; “promotes optimal joint flexibility”; “nutritional support for healthy joints”; “eases pain stiffness and inflammation”.

Verdict

The data does not demonstrate that glucosamine taken alone, or with chondroitin, promotes healthy joints in most people, say the EFSA scientists. Nor is there evidence that it reduces inflammation in joints. Recent studies indicate that glucosamine can benefit people with osteoarthritis, but not the population in general, the scientists say.

Taurine

What is it?

A staple of energy drinks, taurine is an amino acid that is perceived as a sports, bodybuilding and health supplement.

Common claims

“Benefits athletic performance”; “raises energy levels”; “antioxidant activity”.

Verdict

EFSA concluded that studies are too small and limited to prove that consuming taurine gives humans energy, improves sporting performance, delays the onset of fatigue or neutralises antioxidants.

Omega-3 fatty acids

What are they?

The benefits of fish oils such as cod liver oil have been vaunted for many years. They contain omega-3 fatty acids, particularly EPA, DHA and DPA, which are meant to be good for the joints, circulation, heart, and cholesterol levels. Some food products are now enriched with omega-3 fatty acids.

Common claims

“Keeps joint flexible”; “promotes joint health”; “supports good heart health and circulation”; “maintains healthy levels of cholesterol”.

Verdict

The EFSA scientists say there is enough evidence to suggest that consuming these fatty acids helps to reduce blood pressure and blood concentration of triglycerides (a blood fat that has been linked to heart disease). But they don’t see sufficient evidence of fatty acids maintaining healthy joints, lowering “bad” cholesterol or maintaining “good” cholesterol .

Zinc

What is it?

Zinc supplements have become more popular as nutritionists and complementary health practitioners have recommended it.

Common claims

“Antoxidant”; “maintains a healthy immune system”; “vital to health of reproductive system”; “supports thyroid and prostate glands”.

Verdict

If you don’t get enough zinc, your health will be affected. It does help to maintain the immune system, DNA, bones and the reproductive system. But there is no evidence that people in Europe are suffering any of these problems as a result of inadequate intake of zinc, or that zinc improves your prostate or thyroid function.

Dietary fibre

What is it?

Dietary fibre is the name for the carbohydrate parts of foods that are not digestible in the gut. Different types of fibre — particularly “soluble” and “insoluble” — have different qualities.

Common claims

“Lowers cholesterol”; “maintains normal cholesterol levels”.

Verdict

Confusion over fibre is common, say the EFSA scientists. The benefits of fibre in promoting gut health are unquestionable. But fibre’s capacity to control the cholesterol levels is limited to specific types of soluble fibre. Sometimes, scientists say, food manufacturers make claims about the health-giving qualities of their fibre without “sufficiently characterising” the actual type of fibre that it contains.

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