Could a single fruit save the world? You might have thought so, considering some of the recent clamour for goji berries. Health-food evangelists have sung the praises of this Himalayan superfood for several years now and they remain a popular snack amongst the Hollywood elite. They cost around £25 per kilo, or £1.25 for a large handful, which is more than twice the price consumers pay for blueberries and 18 times more than carrots. No-one argues that these are expensive berries, but are they worth it?
I have always said that it is not the cost that is important, but the value (I knew I had repeated this mantra too frequently when an ex-girlfriend used this logic to justify the purchase of some 'beautiful' Jimmy Choos). Impractical £400 shoes aside, the question revolves around the whether these berries offer value above more everyday options. What would could possibly justify the price tag? Champions of the fruit, also known as wolfberries, point to their profuse antioxidant content.
Through their ability to quench free radicals produced during oxidation, antioxidants provide vital protection for the delicate parts of each cell. In doing so, they support critical functions within the immune system and liver and well as sparing us from premature aging. Without a sufficient supply, you may become tired, pick up infections easier, notice inflamed joints and become the proud owner of leathery sun-dried skin. Not what any of us want. Luckily, antioxidants are found in almost all foods in a variety of forms and in a variety of concentrations; as you may expect, proponents of gogi berries identify the fruit as a superior source. But how does this content compare with that found in the humble blueberry? Or other fruit and vegetables?
Enter the ORAC scale. In the early 1990s, some very clever scientists decided to quantify the Oxygen-Radical Absorbance Capacity of each food. They did this by measuring how much oxygen radicals could be neutralised by 100 grams of each food, before using this data to generate a rating for each item. For the first time, nutritionists could now rate foods against one another and agree on the 'best' antioxidant food. The lists compiled since make for interesting reading; while tomatoes and broccoli limp to a score of 546 and 1,500 respectively, blueberries have a capacity of 4,669 (measured in micromols of trolox equivants, or umol TE/100g, if you are interested). And the gojis? Much like the England football team at most World Cups, the red berries arrive to a fanfare but are ultimately left trailing behind the cream of the crop. Scoring 3,290, gojis clearly contain an abundant supply of antioxidants but not nearly the amount that their price tag might indicate.
So goji berries are a waste of money, right? Erm, maybe. There are several problems with this conclusion: for a start, the ORAC scale is not valid. Scientists only measure antioxidant activity of an sample in the laboratory and these vary according to soil conditions, growing season and transport method. Additionally, the process of digestion can transform or remove many chemicals. Take polyphenols, a common class of antioxidant in plant foods; while these compounds demonstrate excellent abilities to quench free radicals in the laboratory, only 5% survive the digestive process. This in itself trivializes the concept of the ORAC scale. Even more importantly, foods can help the body in many ways beyond simply antioxidant content. A quantitive scale can never take into accounts such a complex set of factors and, as a result, will always mispresent. Phytonutrients provide benefits independently of its vitamin content, mineral provision or ORAC score.
For example, the humble carrot remains a steward of heart health. While not faring so well on the ORAC scale at just 697, studies continually show an association between consumption of the vegetable and reduced cardiovascular disease. Whether this is due to the beta-carotene content, or whether it is due to the polyacetenes, hydroxycinnamic acids and anthocyanidins, remains a matter for discussion. I would guess that all contribute to the effect, but the scientific community cannot measure the changes inside the body induced by isolated chemicals and, thus, cannot say for certain. Accordingly, we cannot agree on whether the zeaxanthin and coumaric acids of goji berries benefit the body more than the flavonols and procatechic acids of blueberries. Maybe they do, maybe they don't.
So the take-home message is this: Goji berries are expensive and probably about as good as blueberries. Their value lies in the eyes, stomach, and wallet of the beholder. Additionally, we have learnt that eating by numbers is silly. Eating an array of phytochemicals from wide range of good foods is sensible. But comparing fruits to decide which one is best is pointless. It's literally a case of apples and oranges.