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The Great UK Vitamin Scare {1}


UK media have persistently refused to mention a single milligramme: the image of worried people bringing in bagloads of vitamin and mineral bottles to ask the pharmacist at Boots whether what they are taking is o.k. is ridiculous. What is the bloody internet for?

What is a high dose? It’s useless to lump all vitamins together. Each one has to be dealt with separately. The main news reports mentioned vitamins A, C, D and E. No figures were given for doses.

In any case, this issue is heated because it is a battle between the vitamin manufacturers and sellers (and their scientific data) and ‘sensible’ science (and conventional medicine). It is virtually impossible to talk about how much of any one vitamin you can take without dealing with the general debates such as do we need to take supplements at all and are we being given the facts?

Let’s take one vitamin, B6, not mentioned in the reports, and see what we can find.

It take seconds to discover the suggestion that over 200mg. per day of B6 can cause nerve damage when taken for long periods, though stopping reverses the damage.

This official looking website, Office of Dietary Supplements, under the auspices of the National Institute of Health (U.S.), in its B6 Fact Sheet suggests 100 mg. daily as the safe level. It is pretty scathing (about the efficacy of B6 (therapeutically) where there is little or no evidence. Several experiments show that placebo is effective as therapeutic doses.

The daily recommended target (RDA) in the U.S. is 1.3 mg. for men and women between 19-50 years of age : a balanced diet would (should) provide this level. A banana a day would give you 0.68 mg., a baked potato, 0.7 mg.

For lowering homocysteine levels (implicated in heart and vascular disease): 3mg. per day. Eat more healthy food! Some suggest taking 50 mg. a day (about 74 bananas). However, SEE B6 Fact Sheet :

What is the relationship between vitamin B6, homocysteine, and heart disease?

A deficiency of vitamin B6, folic acid, or vitamin B12 may increase your level of homocysteine, an amino acid normally found in your blood. There is evidence that an elevated homocysteine level is an independent risk factor for heart disease and stroke [my italics] The evidence suggests that high levels of homocysteine may damage coronary arteries or make it easier for blood clotting cells called platelets to clump together and form a clot. However, there is currently no evidence available to suggest that lowering homocysteine level with vitamins will reduce your risk of heart disease. Clinical intervention trials are needed to determine whether supplementation with vitamin B6, folic acid, or vitamin B12 can help protect you against developing coronary heart disease.

One report suggested that B6 may protect against heart disease in other ways (i.e. not connected to homocysteine).

For what sort of things do people take B6 in therapeutic doses?

That is: self-administered or under medical advice.

  • Cardiovascular disease and strokes
  • depression
  • insomnia
  • carpel tunnel syndrome
  • PMS
  • asthma
  • epilepsy

Three quite interesting areas:

(1) Pre-mentrual tension.

Said to help relieve the symptoms. Suggested it clears excess oestogen. [ {1}’ Oestrogen leads to depression because it does not only block vitamin B6 activity but also accelerates the metabolism of tryptophan, thereby leading to low serotonin levels and hence to symptoms associated with these. ‘ ]

(2) Depression

Up to 25% of people with depression may be deficient in B6.

Diagose-me.com:

A study found plasma pyridoxal-5-phosphate (active vitamin B6) levels were about 48% lower in depressed patients than in controls, a statistically significant finding. 57% of depressed patients, but none of the controls, were B6-deficient. When B6 nutriture was evaluated by enzyme stimulation testing (a more sensitive method), all the depressed patients and none of the controls were deficient. [Russ CS et al. Vitamin B6 status of depressed and obsessive-compulsive patients. Nutr Rep Int 27( 4): pp.867-73, 1983]

(3) Epileptic seizures

Role in building blocks for neurotransmitters. May reduce frequency of attacks.

(4) Diabetes

May reduce risk of nerve damage.

::

The information sheet {1} says:

Vitamin B6 supplements have been tested extensively for toxicity by a number of research groups. No evidence of toxicity has been reported in human trials using 225mg of vitamin B6 daily for one year (56), or taking 250-500mg for an average of 2.3 years (57). A review of vitamin B6 toxicity states: “there are many reports stressing the absence of toxic side effects in people taking 200-500 mg per day for extended periods” (58). This also became apparent when Brush and Perry followed 630 women who had been taking up to 200mg of pyridoxine per day for years, none reported any side-effects whatsoever (59).

refs.

57. Mitwalli A et al: Safety of intermediate doses of pyridoxine. Can Med Assoc, 131:14, 1984

59. Brush MG, Perry M: Pyridoxine and the premenstrual syndrome. Lancet, 1:1399, 1985

This by Jurriaan Plesman, a clinical nutritionist {2} discusses drug therapy over nutrition in depression.

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April 17, 2008 - Posted by | medicine, science, vitamins | , ,

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