The Value of Vitamins

It all started with the important discovery of vitamin deficiency diseases like scurvy, pellagra and rickets and now it's become a huge industry. You can hardly venture onto public transport without seeing adverts for supplements on railway stations, in tube trains or on the backs of buses. Anyone would think vitamins and minerals were to the body what oil is to the engine of a car - a simple top up and smooth running is assured.

It's very hard for the average consumer to make informed decisions in this area - the products sound tempting and "everyone's" taking them, so they must be good, mustn't they?

Doctors tend to be conservative on the subject - "you only need vitamins if you have a vitamin deficiency disease" would be their traditional position statement.

"Nutritionists" are far more liberal. They believe that vitamins not only prevent diseases but can also "heal" all manner of ills. They recommend a vitamin (or six) for every ailment. As if that extra oil in the car could mend a broken engine part. They tend to be overly eager to support their beliefs by citing  evidence from experiments involving cells and mice.

In the middle ground we have the lucrative supplement industry with a vested interest in convincing us that we need supplements and so getting us to part with our money.

So what's the scientific take on all this?

Evidence cannot convince the scientific community unless it involves a large group of humans (not genetically modified mice), taking vitamins over a long period of time, with a "blind" comparison group taking placebos. Only then can you check whether the supplements are safe and whether any positive effects result. Such trials are, of course, very expensive and are consequently rather rare. Such studies that do exist have sometimes shown no benefit, or even demonstrated harm to those who take vitamin supplements for long periods.

In summary - the better quality evidence has generally been "disappointing" inasmuch as it has failed to show that supplements reduce your chances of avoiding colds or cancers, or that they increase your chances of living longer. Vitamins cure vitamin deficiency diseases, but evidence that they are curative in other areas is very flimsy indeed.

The other problem for consumers is that vitamins are very lightly regulated. In Europe, now, you cannot even hint on packaging that a food has an active health benefit. There are only a few examples that are approved by the European Food Standards Agency (notably oats and the cholesterol-lowering products such as Benecol margarine). Food packaging is still allowed to bear words like "fortified with Vitamin A" or "a source of vitamin C" as long as they contain minimum amounts of the relevant nutrient.

Where food supplements are concerned, as long as they are not actually toxic or contaminated and as long as they make their claims in qualified terms such as "may help support a healthy immune system" they are very lightly regulated. In other words there is not a lot of consumer protection.

Cochrane systematic reviews are a good place to look if you want to check the best evidence about supplements. A new book has been published which goes into more myth-busting detail and it looks like interesting reading.

http://www.thecochranelibrary.com/view/0/index.html

http://www.guardian.co.uk/lifeandstyle/2013/jun/07/vitamins-stop-taking-the-pills?INTCMP=SRCH

A Healthy Glass of Juice?

I'm going to stay with the vitamin C theme and talk about fruit juice. It is a delicious drink, particularly freshly-squeezed orange juice. But it is also a triumph of marketing.

In the Second World War the British Ministry of Food worried, probably unnecessarily, that children would be deficient in vitamin C. Fresh, imported fruit was rare but people did consume quite a lot of vegetables - so their vitamin C consumption was probably fine. But juice drinks were recommended for children as a supplement. Blackcurrants and rosehips were home-grown sources of fruit concentrate. Those of us who grew up in the post war decades remember concentrated orange juice from the NHS clinic. 

Meanwhile the orange growers of Florida were promoting orange juice, and doing so very successfully. OJ, as it became known, became a standard part of the diet in the United States. Every good mom dispensed it liberally. I visited Las Vegas once and it was being doled out to breakfast-buffet-eaters by the pint. As soon as your glass was nearly empty, someone would offer to fill it.

Since then fruit juice in various forms has become a regular feature in most British shopping trolleys. It maintains an image of being a healthy drink, riding on the back of the stellar success of vitamin C. (see previous post)

But is it really healthy?

The recommended daily intake of Vitamin C varies between countries but is always under 100mg. A 250ml glass of vitamin C contains about 120mg of vitamin C, more than our daily requirement. How much is 250ml? It is an American 'cup' or a large wine-glass full. It may contain a few other useful micronutrients but it also contains a lot of sugar.

Every 250ml glass of unsweetened juice contains the equivalent of 8 teaspoonfuls of sugar - similar to non-diet cola. And this of course accounts, in part, for its success. From cradle to grave we adore sweet things. And the more we eat, the more we crave.

Dentists disapprove of regular juice consumption - the sugar encourages decay and the acidity of the juice erodes enamel.

Dietitians are not keen either - they grudgingly allow that a small glass of juice can be counted as one of your "five-a-day". Their recommended serving is 150ml. In other words a small wine glass size. You can't achieve your five-a-day target by drinking 750ml of juice. You can only count one.

Increasing rates of obesity and type 2 diabetes are undoubtedly fuelled by consuming sugar and there is no reason to think that sugar-laden juice is somehow exempt from blame. The fact that it claims to be healthy perhaps makes it more culpable. There is no reason to think juice, in anything other than small quantities, is a good choice if you are trying to eat a healthy diet.

What about "juicing" then? It is quite entertaining, if you have a cheap source of fruit and a user-friendly machine. But is it "healthy"? I suggest that if you have a sick person to look after, one who is not eating well for more than a couple of days, then juicing may have a role - fresh juice offers palatable fluid and calories if calories are a priority.  But the idea that it is otherwise beneficial to health has no foundation.

Milk, water and unsweetened teas are better ways of consuming fluids than any form of sweet drink. Vitamins are better obtained by eating a variety of whole fresh fruit and vegetables. If you want to a citrus-flavoured drink when you have a cold, consider options that don’t contain lots of sugar - fruit or ginger tea bags, sweetened with just a little honey or marmalade.

Vitamin C – A Cure For Colds? Really?

Winter is just around the corner, so I’ll start with the health claim we all know best: vitamin C prevents colds and flu and alleviates the symptoms of these irritating ailments.

There is little evidence to support much of a case for vitamin C supplements, despite the publication of enough research papers to build a small hill.

Cochrane Collaboration scientists, after systematically reviewing all the well-designed studies they could lay their hands on, concluded that there is no evidence that supplements of vitamin C prevent colds. There is, they conclude, a small reduction in the severity and duration of colds in those taking regular supplements.

It is possible, they go on to say, that massive doses (e.g. 8 grams), at the onset of a cold may help symptoms but there are too few trials to be sure. The jury is still out on this and doses of this size can cause diarrhoea. And remember the effects that are found in some (but not all) studies are minor, not curative.

There is some evidence that for those indulging in arduous physical activity – marathons and so on - vitamin C can help to reduce their incidence of colds. So if you are entering a triathlon or climbing a mountain then make sure your diet contains plenty of fruit and veg.

So what are the other facts?

Severe deficiency of vitamin C causes scurvy. This is a disease in which the walls of blood vessels cannot repair themselves. Sufferers eventually die from bleeding (and not, apparently, from infections). So we are certain that vitamin C is essential to the body if it is to carry out repairs. It is also used by cells, including immune cells, but they only seem to need a small amount.

You have to be eating a terrible diet for several weeks to get scurvy – one that contains no fresh food. If you are an Arctic hunter eating plenty of fresh meat you will be fine. If you eat chips and burgers and nothing else, you will not get scurvy. If you ate only cake and sweets you might.

There is circumstantial evidence that people who eat lots of fruit and vegetables tend to be healthier but there is no reason to think that vitamin C is the magic ingredient. When we eat fruit and veg we get a range of benefits and extracting pure vitamins and consuming them as supplements does not seem to be the same thing at all.

So, my conclusion is that we should not be seduced into buying products that claim to have added vitamin C or wasting our money on vitamin C supplements. Spend money on fruit and veg instead and you will get your vitamin C along with the other nutrients.

Here’s the link to the Cochrane article.

http://bit.ly/Xgdysx