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Two-thirds of us have bought something because it's popularly believed to be a "superfood", with 14% of us willing to pay more for something with the "superfood" label. But are these superfoods really "super"? Do these foods, which we trust to cure all our ills and pack us full of brimming health and general joie de vivre, have any advantage over other food, or is it just a clever marketing gimmick?
Here, we explore the facts behind the claims of our most popular superfoods.
What is it: A good source of antioxidants, iron and folate.
The claim: Beetroot juice lowers blood pressure.
The facts: Beetroot is rich in nitrates, which converts to nitric oxide. Nitric oxide is a chemical thought to lower blood pressure. Beetroot juice is thought to lead to a modest reduction of blood pressure, but more evidence into long-term effects is needed.
The claim: Beetroot juice prevents dementia
The facts: A 2010 study showed that blood flow increases to certain areas of the brain when drinking beetroot juice. This effect was only short-term. Furthermore, there's little evidence that a diet high in nitrates helps prevent decline in cognitive function.
The claim: Beetroot juice boosts performance
The facts: A 2013 study found that amateur athletes experienced modest improvement from drinking beetroot juice. Professional athletes did not.
The risks: Excessive consumption of beetroot has several side effects including: kidney stones and gout (this is due to high levels of oxalates). You can also suffer Borscht urine (beetroot-coloured discolouration of the urine). While this is harmless, it can lead to many painful and invasive investigations before it is diagnosed.
The conclusion: While not necessarily "super", beetroot juice is good for you. But don't drink too much.
What is it: A little berry, high in antioxidants, Vitamin C, fibre and manganese.
The claim: Blueberries cut high blood pressure and artherosclerosis.
The facts: Studies have been inconclusive. One 2015 study of 48 post-menopausal women showed a small but significant reduction in blood pressure when participants were treated with blueberry powder. However, another 2015 study of 44 adults with metabolic syndrome (a disease which combines obesity, diabetes, and high blood pressure) did not respond positively to a regime of blueberry smoothies.
The claim: Blueberries prevent cancer.
The facts: Several animal studies suggest that blueberry extract reduces the amount of free-radicals, which are thought to cause cancer. It's unclear if this effect is replicated in humans.
The claim: Blueberries improve memory.
The facts: Several studies (either animal studies, or human studies with small samples) suggest that blueberry extract consumption may lead to improved memory. No link is proven.
Risks: If you're diabetic, you still need to watch your fructose (fruit) intake, as fruit is turned into glucose in the body. Otherwise, safe.
The conclusion: Good for you, but just one more berry. You could mix them with strawberries, which are shown to have the same heart-healthy effects, are lower in fructose, and have - let's face it - a more popular taste.
What is it: Chia is a seed, popularised by the likes of Gwyneth Paltrow. It's a source for magnesium and omega-3.
The claim: Full of health-boosting, Omega-3 Fatty Acids, essential for healthy hair, nails, and brain-power.
The facts: A 2006 study by Wang and colleagues found that the plant-oil supplements of Chia Seeds did not give the same health-giving properties as fish-oils.
The risks: Chia seeds have been found to swell into a gelatinous mass in the stomach, cause constipation, and to raise the risk of a cardiovascular event in patients with diabetes.
The conclusion: To boost your omega-3 fatty acids, you'd be better off having a nice fillet of salmon.
What is it: Popular with celebrities like Madonna, Goji berries are regarded as the A-Lister of Superfoods. It is high in Vitamin C, Vitamin B2, iron, selenium and antioxidants.
The claim: Goji berries boost cardiovascular health, immunity and life expectancy.
The facts: All studies potentially suggesting this used very small samples and highly concentrated amounts of Goji juice unavailable outside a laboratory setting. Even then, the research is inconclusive.
The claim: Goji berries prevent cancer
The facts: A 1994 Chinese study treated 79 patients with advanced cancer with Goji berries. It was found that immunotherapy and Goji berries helped the cancers regress. No information about the immunotherapy or other methodology used is available, so we can't say if this is exciting or significant or not.
The risks: Goji berries interact with certain medications, including warfarin, and certain diabetes or blood pressure medications.
The conclusion: The evidence supporting the use of Goji berries as medicine is weak. Your money would be better spent on a range of fresh fruits and vegetables. .
What is it: A traditional Chinese medicine, high in B-vitamins.
The claim: Green tea protects against cancer.
The facts: A 2009 meta-analysis looked at 51 studies of over 1.6 million people suffering with breast, bowel, prostate, mouth and lung cancer. They found that evidence of green tea protecting against cancer was "weak" and "contradictory".
The claim: The antioxidant catechin and the caffeine in green tea aids weight loss
The facts: A 2012 review of nearly 2000 participants found no significant relationship between drinking green tea and weight loss.
The claim: Green tea cuts cholesterol
The facts: A review of 11 studies and 821 people (2013) found that green tea does lead to a slight, but significant reduction in cholesterol and blood pressure, at least short-term. It's believed this is due to the catechin.
The risks: Green tea is safe if drunk in moderate amounts. If drunk to excess, long-term, you can start suffering side-effects due to caffeine. These effects include heartburn, insomnia, headache, and mood swings.
The conclusion: If taken in moderation, green tea is safe to enjoy. But there's little evidence that it is as super as some claim.