Eat your greens - pricey superfoods come and go
Superfoods are the second coming of food and the salvation against illness. With the backing of celebrities like Gwyneth Paltrow and Madonna, they have cachet. Paltrow's cookbook It's All Easy contains foodstuffs and dishes such as acai, bibimbap, kimchi fried rice, congee, along with more mundane stuff such as fried egg sandwiches, turkey meat loaf and avocado on toast. Eating her diet for a week costs $470 (€421) per week, according to eonline.com news. Hardly affordable for the person living on the minimum wage or even on one a good deal higher.
A fundamental problem is that superfoods have no scientifically agreed definition. The Oxford dictionary defines them as "a nutrient-rich food considered especially beneficial for health and well-being". By that definition, many of our everyday foods, such as cabbage, can be so described - although it is hardly as exotic sounding as goji berries and is not promoted by film stars.
Superfoods are essentially those that are particularly high in certain nutrients such as antioxidants, proteins, specific vitamins etc. Since 2007, the European Union has banned the use of the term on packaging unless the claim is backed up by convincing evidence. In the US, the Food and Drugs Administration has no such requirement but it can take action if the claims made turn out to be false.
So why has the public fallen for these 'superfoods'? Prefixing the word 'food' with 'super' gives it a certain power. Fashion and food magazines scream with headlines and beautiful photos of their life-saving properties, with the emphasis on colour and freshness. Just looking at them is almost a mystical experience. Meanwhile, the person on the street absorbs the messianic message delivered by the lifestyle goddesses.
It is known that many illnesses are linked to our environment to some extent and some believe that the cause and effect link between the world we inhabit and the illnesses we develop is universal and applies to all illnesses. This fits with our sense of agency, that we have some control over our destiny and that with a proper lifestyle we can prevent the terrible onslaught on our body that disease brings.
Diet is central to this and it is true that a poor diet is associated with poor health. Just look at the obesity figures. However, a healthy diet does not necessarily need kefir or coconut water any more than beetroot juice or kale smoothies should top our shopping list. Governments spend billions each year trying to persuade people to eat a healthy diet of fruit, vegetables, and varying quantities of protein, fats and carbohydrates. A standard, well-balanced diet will contain sufficient nutrients to keep us healthy - but we should remember that we are mortal, and illness cannot be eradicated.
What is the evidence that superfoods are uniquely health giving? In psychiatry, only omega-3 oils have any evidence to show that they may help in preventing depression, although the results in schizophrenia were mixed. Omega 3 oils are found in oily fish such as mackerel and salmon yet they are not marketed as superfoods. The trendy superfoods now are kale, avocado, quinoa, blueberries, chia seeds, pomegranates and beetroot.
And what about kale, now ubiquitous in supermarkets, and its possible role in preventing cancer due to the glucosinolates it releases? As a child I recall it being fed to cattle. Yes, there is some evidence to support the claim that it reduces the risk of cancer of the gut and lung. However, cabbage, Brussel sprouts and spring greens are just as efficient and are much cheaper. According to Professor Tim Spector, of King's College London and author of The Diet Myth: The Real Science Behind What We Eat, many of the studies on 'superfoods' have been carried out on animals or even on cells in a petri dish. For example, in a study using pomegranates, a molecule from the fruit was given in high doses to a type of worm and it was found to prolong their 10-day life expectancy by 45pc.
According to Spector, some of these studies take a single element of the substance and administer it in doses that could be dangerous to humans. Other studies have small sample sizes and some are carried out on healthy rather than ill subjects. In short, he says there are methodological flaws to some studies. Our diet has many components which interact, yet the studies sometimes consider one part in isolation and are removed from everyday dietary practices.
So mammy's diktat to "eat your greens" is a sound piece of advice. If you doubt her, Google NHS Choices Superfoods. Those who are bewildered or confused by the superfood message should check it out.
Health & Living