It's a funny business, nutrition. Sports nutrition is even funnier. While a Government scientific committee has issued a warning that taking more than 10mg of B6 a day 'may damage nerve endings', the Colgan Institute of Sports Nutrition in San Diego, California, actually recommends taking 150mg daily to boost the oxygen-carrying powers of the blood. Notice the title of the American establishment; its sole purpose is to discover what is 'optimum' sports nutrition. So what do they have to say about the allegation of 'nerve damage'?

'Taken in large amounts (500mg to 5 grams) for months or years, vitamin B6 does cause severe damage to nerve endings. Some cases of nerve damage have been reported at an intake of only 117mg a day. Fortunately, most cases clear up spontaneously within six months of stopping supplementation.'
That said, one wonders why the Institute still advocate 150mg of B6 a day for athletes 12 weeks before a major competition? To answer that, we must take a closer look at this vitamin. Vitamin B6 (pyridoxine) is found in avocados, bananas, bran, brewer's yeast, carrots, flour (wholewheat), hazelnuts, lentils, rice, salmon, shrimp, soyabeans, sunflower seeds, tuna and wheat germ.

The reasons for ensuring an adequate intake is that B6 contributes actively to many chemical reactions of proteins and amino acids. It also helps normal brain function. But for the athlete it plays a vital role: it promotes normal red-cell formation. Athletes need to maximize their red cell count. It regulates the excretion of water. Another key key factor for athletes is that B6 is concerned with energy production and resistance to stress. One of the ways it does this is to make iron in the diet more available - more iron, more haemoglobin and more oxygen available for the working muscles. Another way it produces energy is to make carbohydrates more burnable for mitochondria (furnaces within cells).

A vast range of 'magical powers'
Let's now look at the unproved and speculative benefits of B6. It is said to treat or prevent depression when used with oral contraceptives, and also to alleviate pre-menstrual tension. It has been used for the latter for about 35 years at around 100mg a day. Other magical powers attributed to B6 include: helping arthritis, curing migraines, relieving nausea, treating diabetes, helping mental retardation, improving vision, aiding weight-reduction, helping infertility and curing carpal tunnel syndrome (a painful condition of the wrist often caused by repetitive strain injury). That's quite a list! However, the vitamin does not work alone. It must have B2 (riboflavin) and magnesium alongside it in adequate amounts.

Now we come to some revealing research. Twelve male marathoners were asked to double their training load of eight miles a day for 20 days at a paltry 8.5 minutes per mile. All of them showed large reductions in haemoglobin and haematocrit (the proportion of red blood cells). Over the period, their usual nutrition was unable to maintain the blood components essential for carrying oxygen to their tissues. The principal nutrients involved in making red blood cells are zinc, folic acid, vitamin B6, vitamin B12 and vitamin C.

In a double-blind crossover trial, the Colgan Institute fed athletes increased levels of these nutrients over a 12-week period, during which they increased their training levels. They were compared with a control group who were given 100 per cent of the RDAs for all nutrients. The athletes given additional nutrients maintained their red blood status, increased their VO2max and improved their performance. One of my own athletes on the same regime for the same period completed in a half-marathon in France; en route she ran a personal best 10K time, a personal best 10-mile time, and won the race in a new record time! She subsequently gained her first New Zealand international vest.


Are we deficient in B6?
Now, one would think that with all the foods available that contain B6 (about 18 of them), the chances of a deficiency occurring would be remote. Not so. First of all, cooking food that contains B6 in large amounts of water reduces its nutritional value by 33 per cent. Freezing vegetables with good B6 content results in a 30-56 per cent reduction in value. And if you rely on canned food for your B6 supply, there is a whopping 57-77 per cent loss. What do surveys reveal? The Nationwide Food Consumption Survey in America found that B6 intake is deficient in 33 per cent of households. In a recent study at the Colgan Institute, 58 per cent and 73 per cent of two groups of athletes were B6-deficient.


So what's the bottom line?
The Government may or may not lift its proposed limit on the free sale of B6 to 10mg daily (Food Safety Minister Jeff Rooker was due to make his decision after PP went to press). The health-food industry, of course, has challenged the limit, because the sale of B6 to women is big business. Is the Government in danger of over-reacting? For every over-dosed B6 victim, there are an estimated 12 million people in the UK who have an inadequate intake (using the US survey as a yardstick). Have you ever met a person who said: 'I'm suffering from B6 toxicity'? I've met many who have said: 'I'm suffering from alcoholic poisoning', yet the Government hasn't ordered that a person cannot be served more than one pint of beer in any one pub!
What's the best way to ensure a good intake of B6? Rely on uncooked sources. A banana chopped up with cereal for breakfast, a banana sandwich with mid-morning coffee, plus an avocado starter for dinner, will go a long way towards maintaining the status quo. If you want to try the Colgan Institute blood-boosting formula (quite legal), remember you're only meant to continue it for 12 weeks and no longer. Here it is (per day):
2.4mg of folic acid
100mcg of vitamin B12
150mg of vitamin B6
500mg of vitamin C
48mg of iron
60mg of zinc
50mg of vitamin E
That lot will cost you about £35 for a six-weeks supply. Don't forget to train hard as well!
Frank Horwill