We have all been told that we should add a handful of blueberries to our morning cereal, and that a cup of green tea would be much healthier than a standard brew.
But is there any truth behind the “super” in superfood? Or are we simply slaves to the latest fad promoted by health food brands?
The NHS worked alongside the British Dietetic Association to investigate whether many of the so-called superfoods really do offer health benefits above and beyond what most foods can give.
The results show that while many superfoods may contain benefits that have not yet been uncovered, there is currently very little to suggest that they are better for you than other, often less expensive foods.
The only superfood considered very likely to provide particular health benefits is oily fish.
Scientists' interest in oily fish came from observations of Eskimos, who eat a large quantity of it and have fewer heart attacks and strokes than most people.
According to a study by the UK Scientific Advisory Committee on Nutrition, there is a “large body of evidence” to suggest that fish consumption reduces the risk of cardiovascular disease, to such an extent that the government recommends we eat at least two portions a week.
It works by reducing fat build-up in the arteries and so lowering blood pressure. But when it comes to prostate cancer and age-related vision loss and dementia, there is no such evidence of benefits provided by oily fish.
These purportedly protect against heart disease and some cancers, while improving memory. A number of studies suggest that there might be some level of health benefit, but there is nothing conclusive.
For example, one recent experiment showed how blueberry extracts decrease the free radical damage that can cause cancer. However, it is not clear how well humans absorb these compounds from eating blueberries and whether or not they have a protective effect.
In the case of heart disease, a 2012 study found that 32 per cent of women who ate three or more portions of blueberries a week had a lower risk of heart attack compared with those who ate the berries once a month of or less, but there was no evidence to show that it was the berries, rather than some other factor, that was causing the lower risk.
Some people believe that Goji berries boost the immune system, enhance brain activity, protect against heart disease and cancer, and increase life expectancy.
Yet there is no reliable evidence whatsoever to suggest that these benefits are real. Most of the research into these conditions have been small-sized, of poor quality, and performed in laboratories using purified and highly concentrated extracts of the goji berry, according to the NHS.
Alison Hornby, a dietitian and BDA spokesperson, said the inconclusive benefits do not warrant the higher cost of goji berries compared to most other fruits and vegetables. "Various goji berry products are sold as health foods, but the evidence of their health benefits so far comes from scientific studies using purified extracts of the fruit at much higher concentrations than the products contain,” she said.
"As these products tend to be relatively costly, it makes sense to stick to eating a range of fruits and vegetables rather than spending your money on this one item with no proven health benefits." -
Perhaps the food whose “super” qualities we most want to be true, dark chocolate has been praised by a number of food brands for its anticancer and stress relief properties.
But the idea that dark chocolate is good for you has very little scientific backing. Most of the studies into its supposed ability to lower blood pressure have produced unconvincing results, and the tests themselves were often too short in duration to be able to base any conclusions on them.
Similarly, tests of dark chocolate's anticancer and anti-stress properties have offered little evidence to suggest the claims are true.
“The potential health benefit of some compounds in the chocolate have to be weighed against the fact that to make chocolate, cocoa is combined with sugar and fat,” said Hornby.
Green tea is thought to contain a particularly high level of antioxidants when compared to other types of tea, and has been used to treat ailments such as headaches and depression for centuries.
Various health brands have described it was encouraging weight loss, reducing cholesterol and combating cardiovascular disease, but in fact there is no evidence to suggest any of these qualities are true.
Health brands have claimed that wheatgrass offers higher nutritional content than any other vegetable, and that it offers protection against inflammation and is able to improve circulation by building red blood cells.
They say the chlorophyll it contains is similar in structure to the oxygen-carrying haemoglobin found in animals, and that drinking it will therefore enhance haemoglobin production.
But there is absolutely no evidence to support this claim, and the NHS found that the pound-for-pound nutrient content of wheatgrass juice is roughly equivalent to that of common vegetables such as spinach and broccoli.
"There is no sound evidence to support the claim that wheatgrass is better than other fruits and vegetables in terms of nutrition,” said Hornby.