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Vitamin B6 and red-blooded
athletes
by Frank Horwill Why all the fuss about vitamin B6, and what does it mean to
athletes, anyway?
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 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 8½ 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 VO2
max and improved their performance. One of my own athletes on the same regime for the same
period competed in a half-marathon in France; en route she ran a personal best 10km 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): That lot will cost you
about £35 for a six-weeks supply. Don't forget to train hard
as well!
Frank Horwill
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