Edible berries have been part of our diet since hunter-gatherer times, and feature in both food and pharmacy records through the ages.
In our childhood, we sang as a nursery rhyme “Here we go round the mulberry bush”, but we had little idea that the berries were for eating; it was the leaves we used at school to feed our silk worms. Now, on the other hand, we all knew about the summer fruit picking of strawberries, gooseberries, raspberries and elderberries, though I doubt whether we knew that their vitamin C contents (as with the mulberry) were of the order of 30 to 50 mg per 100 g of fruit. The ubiquitous blackberry (bramble) does not make the grade with its humble 6 mg per 100 g in the wild.
Notwithstanding a paucity of knowledge of its vitamin C content, the juniper berry, has flavoured gin for centuries. As with the sloe berry (slaes in Scotland), best picked after the first frost if the birds have left any by then, and used to transform gin into a connoisseur’s liqueur. Then there is the blackcurrant. A superior kind of berry, and much favoured by grannies, to help ward off the worst of the winter’s colds. And if vitamin C has anything to do with it, then the hearty 180 mg per 100 g of fruit accounts for its position at the top of the league table. Incidentally, the Scandinavian and North American cloudberry with its impressive 160 mg comes a close second. Perhaps you have sampled the liqueur?
Those other American imports: the cranberry – until recently only to be taken with the turkey at Christmas but now readily available in juice form (and verboten for warfarin takers), and the huckleberry, are at the bottom of the table with scores of less than 10 mg per 100 gm fruit.
Sadly, from here on the nomenclature gets out of hand. Is the huckleberry the same as the blueberry? Experts say the difference lies in the seeds. Hmm, and what is the blaeberry if it isn’t a Scottish blueberry? And the bilberry, marionberry, barberry, and whortleberry, the cowberry (or lingonberry), the christmas berry and the late 19th and early 20th century American inventions, of the loganberry and the boysenberry respectively? The Cape gooseberry from, er… The Cape of Good Hope, and the tayberry et al. from Scotland. Whatever they are called, their C vitamin scores are generally uneventful, and grannie remains unimpressed.
And then the scientists at the SCRI (Scottish Crops Research Institute) did the obvious thing and set about upgrading the best of the bunch, the blackcurrant, replacing the familiar varieties with the various Bens, e.g. Ben Nevis. And a recent grant of £1.2M is being used to give us the super blackcurrant. The force be with you!
But while we have all been concentrating solely on upping our C vitamin intake, the foodies suddenly switched their interest to antioxidants in general, and in particular, in the case of the berry, to the red/blue coloured pigments – the anthocyanins, and hailed from the bush tops their universal anti-cancer properties. Alas, there are hundreds of anthocyanins, not all of which have five star status, and to make things worse, according to Professor Gary Duthie of the Rowett Research Institute in Aberdeen, “in humans the anthocyanins are poorly absorbed. Any that are, may break down before they reach the sites where oxidative damage takes place.” So, just when you thought things couldn’t get worse, anthocyanins are but one of several chemical classes of antioxidants found in berries, none of which we know a great deal about. The yellow/orange carotenoids are an important and complex class, joined by a whole slew of flavanoids that compete for a place as therapeutic, natural phytochemicals. There is some evidence that the carotenoids may be better absorbed than the anthocyanins. But, others would point out that carotenoid radicals - formed by interaction with unwanted free radicals - are themselves pro-oxidants, oxidising valuable components unless other antioxidants are present. So, if we are to make intelligent choices about which berries to eat, we need to know which ones contain what, and how much we need of it to allow for their different absorption rates and potencies. When total antioxidants become the main issue, the humble hedgerow blackberry re-enters the arena as a front runner with, according to some sources, the highest concentration of all fruits – a plucky assertion to say the least. However, the concentration falls on maturity – which is academic since few of us will want to eat immature blackberries simply to imbibe high levels of antioxidants! Nevertheless, it is clear that we must keep an open mind when rating the overall best berry for human wellbeing, not least because the total antioxidant listing is not blessed with as long a history as the more reliable vitamin tables (see United States Department of Agriculture, Food and Nutrition Database). A non-scientific survey recognises cranberry, blueberry and blackberry as leaders, and therefore together with a reasonable vitamin C score, they are contenders for the title.
But where are the currants, red and black? Well, it would seem that the redcurrant is an intermediate species and even the favoured blackcurrant may be relegated to fourth place for total antioxidant content. By limiting our interest to berries, excludes cherries. Otherwise, the acerola cherry would win hands down when it comes to vitamin C content, weighing in with a massive 1700 mg/100g fruit.
Having strayed into the area of botanical exactitude, which up to this point has been assiduously avoided: how many of the aforementioned are true berries? Relatively few I fear. But press on regardless. Can we therefore, accept the fruit of a palm tree as being a berry?
If so we have a new berry on the block. The recent media coverage of the “super berry”, referring to the acai fruit from the Brazilian rain forests which looks set to challenge the blackcurrant, being judged the fruit with the highest antioxidant content (so far). But then there has also been coverage of the goji berry, alias wolfberry (lycium barbarum) from Tibet, which picked up the most astounding accolade of all “the richest source of carotenoids of all known plants on earth" (more beta-carotene than the eponymous carrot). So, stop searching.
In a more scientific study, the chokeberry has a very high total anthocyanin concentration of 1480 mg/100 g fresh weight.
Now, I am sure you have the drift of my beef. What the person in the street wants to know is, to borrow a recent BBC website banner; which of these are “berry good for you”? And how much trouble does he or she have to go to to reap the nutritional benefits, and at what environmental cost? In general, the further away from the source you happen to be the greater the risk of nutritional deterioration. Of course modern preservation methods will reduce the losses, but will increase the carbon footprint, e.g. refrigerated transport. Could it be that 100g of blackberries from the hedge around the local common (or even, for a longer season, out of the cold box at the supermarket) and a couple of tomatoes (botanically, legitimately a berry) thrown in for good measure, might be better than 50g of goji berries from Tibet. Better for whom or what? The planet? Yes. The peasant farmers of Tibet? No. The person in the street? Well, which antioxidants do you require?
Now it is time to get really boring. How many of your five a day portions have you had today? In so doing, do you think you have ingested enough vitamins/antioxidants, or do you need more? You don’t know; what sort of an answer is that? Nutritionists, bless them, are here to help you to decide, but they are often notoriously fickle; they deal in populations, or their extremes, e.g. are you deficient in…. or in surfeit? Is there a tendency in your family to need more or less than the average. We have become familiar with the Recommended Dietary Allowance (RDA), which is calculated to satisfy around 98% of people and appears on food packaging for the common vitamins, and is the antecedent since 1997 of Dietary Reference Intake (DRI) which, inter alia includes RDA, AI (Adequate Intake, where no RDA has been set) and UL (the tolerable Upper intake Level). For example, the RDA and UL for vitamin C are 90 and 2000 mg/day for an adult male. But, what about the all-important non-vitamin antioxidants? Do you know the RDA, or even the AI, for the antioxidant carotenoid, lycopene, a major component in tomatoes? No? [There are 2.5 mg lycopene per 100 g in ripe, raw tomatoes, and 15 mg/100 g in tomato sauce. [To digress; so much for Granny’s condemnation of the ketchup bottle!]. But how much do you need?
Since there are dozens of different chemical antioxidant classes in foods, with hundreds of different compounds in each class, it will be a major task to produce the analytical data on even the major individual substances from even a single berry variety. Therefore, for the time being the total antioxidant content (TAC), must suffice. The recommended amount of antioxidants consumed should achieve an oxygen radical absorbency capacity (ORAC) score of 3-5000 units per day. According to one source, 100 g blueberries is equivalent to 2400 ORAC units, 100 g strawberries gives 1500 units and 100 g spinach gives 1800 units. So with careful choice, your five a day fruits and vegetables could easily provide your ORAC requirements. In the past couple of years, scientists have set about the task of measuring the ORAC for many of our common foods and a USDA database has been developed. Just when the layman was beginning to get the hang of it, the analysts decided that the hydrophilic ORAC assay was leaving out the important fat soluble vitamins and other fat soluble antioxidants and developed a method to measure the lipophilic antioxidants too. So now we have the Total Antioxidant capacity (TAC) which is the sum of the H-ORAC and L-ORAC values. Some examples of these in micromoles TE/100 g are: Blueberry, 6200, Raspberry, 4900, and Strawberry 3500, [Adapted from X. Wu et al., J. Food Comp. Anal. 17 (2004) 407-422. Copyright 2004. Permission to reprint granted by Elsevier.]
Would it help to be able to read the lycopene content on the pack? Not unless we know the antioxidant potency of the compound, and that information is not available for the majority of the antioxidants in the majority of our foods.
So, go ahead and create the super berry, but for goodness sake (sorry about that) be careful while you are topping up the vitamin and antioxidant levels, not to breed out the flavour.
Remember, “a little of what you fancy does you good.” Possibly, the only way we have at present to judge the new berries on the block.