THE B6 CONTROVERSY: What's All The Fuss Over Vitamin B6?

By Bill Sardi, Knowledge of Health, Inc.

It's a simple B vitamin. Yet European health authorities have been battling natural health advocates for four years now over the maximum dosage of vitamin B6 allowed in food supplements. The battle re-surfaced recently despite the fact over 100,000 consumers had voiced opposition awhile back.

Reigniting the vitamin B6 controversy, once again the British Foods Standards Agency says vitamin B6 supplements may be putting the public at risk from overuse and wants to restrict the dosage of B6 to no more than 10 milligrams in food supplements. [Warning on Vitamin Use, BBC News, August 30, 2002]

The vitamin B6 debacle recently broke out into hot discussion in The Lancet, a prominent British medical journal. While some health authorities object to high doses, others come to B6's defense. A group of 220 doctors widely objected to the 10 milligram limit for B6 and wrote a memorandum to the House of Commons Agriculture Select Committee in June of 1998. [The Lancet, Volume 351, No. 9115, May 1998] Other authorities suggest the public is misled over health benefits from vitamin B6 and that labels on bottles of vitamin B6 should include the caveat "of unproven usefulness."

Questionable science used against B6

The scientific substantiation for the 10 milligram limit on vitamin B6 may not withstand scrutiny. One study is a highly discredited telephone survey which is considered to be flawed. Telephone interviewers asked vitamin B6 users if they had any tingling in their fingers, a sign of overdose. They determined that 60 percent of vitamin B6 users taking a mean dose of 117 milligrams of vitamin B6 experienced neurological problems. [Acta Neurologica Scandinavia, Volume 76, pages 8-11, 1987] According to this study's authors, supplemental vitamin B6 should be limited to no more than 10 milligrams per day.

The British Committee on Medical Aspects of Food & Nutrition Policy considers 1.4 milligrams of vitamin B6 to be sufficient for the health needs of most individuals and the suggested 10 milligram daily limit is about seven times that level of intake. The Committee on Toxicity of Chemicals in Food said the lowest dose that produced side effects was 50 milligrams and that a 10 milligram limit in food supplements establishes an adequate margin of safety.

However, if toxicity were a problem there would be a veritable epidemic of side effects since millions of adults worldwide take high doses of vitamin B6 in multivitamins. The 10 milligram limit on B6 seems poorly founded.

Disagreement Reigns

The Health Supplements Information Service in Great Britain, which is funded by drug and food supplement companies, says it is safe to take up to 100 milligrams of vitamin B6 per day on a long-term basis but indicates 200 milligrams per day may be problematic. [HSIS Factsheet]

The U.S. National Academy of Sciences also concluded that there was no convincing evidence of adverse reactions in doses up to 200 milligrams per day. Then a margin for safety was calculated at half that dose and the 100 milligram suggested maximum daily intake was established in the U.S.

Furthermore, in August of 2002 the Expert Group on Vitamins and Minerals in Great Britain issued a paper citing in detail various studies involving vitamin B6 toxicity which confirms nerve toxicity really doesn't begin till 200 milligrams are consumed for a prolonged period of time. [EVM/00/19.Revised August 2002]

The Search For Another Reason

So the science is unequivocal. High-dose vitamin B6 toxicity is very unlikely to occur and when it does it is totally reversible. But efforts persist to scare the public away from mega-doses and to set limits on the upper limit allowed in food supplements. There has to be another reason for the apparent misplaced effort to restrict the maximum dosage of vitamin B6.

Upon further investigation, vitamin B6 may have health benefits that have largely been ignored to date. Vitamin B6 may be a breakthrough treatment for hypertension. The leading researcher in the use of vitamin B6 to treat hypertension is Dr. Sudesh Vasdev, who has been supported for 20 years by the Medical Research Council of Canada.

Dr. Vasdev reports that the big three factors in high blood pressure in humans are obesity, high alcohol consumption and high salt intake. According to Vasdev, dietary supplementation with vitamin B6, vitamin C, lipoic acid or cysteine, nutritional factors that can be purchased over-the-counter in health food stores, can normalize high blood pressure.

Dr. Vasdev says people with hypertension can't metabolize sugar properly. In diabetics a chemical called aldehyde rises in tissues which results in greater contraction of blood vessels and a subsequent rise in pressure. Vitamin B6, lipoic acid or vitamin C increase the level of compounds that bind to aldehyde and thus prevent hypertension and subsequent hypertensive-related strokes and kidney disease.

Cysteine, a sulfur-bearing amino acid, appears to be the key nutrient involved in blood pressure control, says Dr. Vasdev. Vitamin B6 works by raising the level of cysteine. Both animal and human studies confirm Dr. Vasdev's findings.

Scientific Studies Back Vitamin B6 For Hypertension

Small animals given 20 times the recommended dietary intake of vitamin B6 did not develop elevated levels of aldehyde and did not develop hypertension. The conclusion of this study was that supplemental vitamin B6 "may be an effective anti-hypertensive." [Molecular Cell Biochemistry, Volume 200, pages 155-62, October 1999] This would be equivalent to about 34 to 40 milligrams of vitamin B6 in humans.

In another animal study, obese rats supplied with five times the normal intake of vitamin B6 experienced complete resolution of hypertension in 3-4 weeks. The removal of vitamin B6 resulted in the return of hypertension within two weeks. Increased supply of dietary sugar increased blood pressure but vitamin B6 again resolved this problem. [Journal Hypertension, Volume 14, pages 355-63, March 1996]

In a human study, 5 milligrams of vitamin B6 per kilogram of body weight (2.2 lbs) was administered orally for four weeks which resulted in a significant reduction in blood pressure. In this study, a 160-pound individual would have received 363 milligrams of vitamin B6. [Arzneimittelforschung, Volume 45, 1271-73, 1995] That much vitamin B6 may not be needed by the average hypertensive patient since most cases involve marginally elevated blood pressure.

Other Benefits of B6

There is more to the vitamin B6 story. Calcium blocking drugs are widely used to treat hypertension. Vitamin B6 levels have been found to control the effectiveness of calcium channel blocking drugs used to experimentally treat blood pressure in animals. [Journal Hypertension, Volume 11, pages 1357-62, 1993] The influx of calcium into cells which results in the hypertensive response is blocked both by calcium blocking drugs or vitamin B6 in obese or sugar-overloaded rats. [Molecular Cell Biochemistry, Volume 188, pages 137-48, 1998]

Vitamin B6 may directly control blood pressure caused by chronic high alcohol consumption. Vitamin B6 has been shown to prevent this type of hypertension in animals. [Nutrition Metabolism Cardiovascular Diseases, Volume 9, Pages 55-63, April 1999]

Physicians Prefer Drugs Over Vitamins

Despite the fact that over 80 percent of high blood pressure patients are in the moderate problem range and can bring their blood pressure under control through dietary means, most physicians prefer to place their patients immediately on anti-hypertensive medications. A major review of conditions that co-exist with diabetes published in September of 2000 only mentioned pharmaceutical drugs to control diabetic-related hypertension and made no mention of vitamins. [American Journal Kidney Diseases, Volume 36, S-10-17, 2000] While the Working Group on Diabetes, part of the National High Blood Pressure Education Program, reported in 1994 on the association between diabetes and high blood pressure, they confined their recommendations to dietary changes and made no mention of food supplements. [NIH Publication 94-3530, April 1994]

There may be financial reason why doctors prefer drugs over vitamins. It's been said that the average internal medical specialist has to get 500 patients on blood pressure medications which requires them to return to the doctor's office for monitoring and re-prescriptions, in order for the doctor to maintain a financially viable medical practice.

Hypertension and diabetes

Hypertension and diabetes are interrelated diseases. An estimated 60-65 percent of people with diabetes have high blood pressure, says the National Institutes of Health. [NIH News Release, May 30, 2000] Hypertension is twice as common among diabetics as healthy individuals. Hypertension is also two to three times more prevalent among blacks and Hispanic-Americans, the very population that could benefit by an inexpensive non-drug treatment for elevated blood pressure like vitamin B6.

Of the 15.7 million Americans who have diabetes (about 5.4 million of these cases are undiagnosed), an estimated 3 million Americans have both diabetes and high blood pressure. According to the International Diabetes Federation, more than 143 million people worldwide have diabetes and the number is expected to rise to almost 300 million by the year 2025. On a worldwide scale at least 43 million adults may have a type of hypertension that could be controlled by mega-dose vitamin B6.

According to, doctors worldwide wrote prescriptions for antihypertensive medications valued at nearly $33 billion in 2000. The market for anti-hypertensive drugs is projected to grow to $52 billion by 2007, according to Datamonitor. The widespread use of mega-dose vitamin B6 for hypertension would threaten billions of dollars of pharmaceutical company sales.

Side effects from antihypertensive worse than B6

While European researchers squabble over the alleged side effects emanating from relatively low-dose vitamin B6 (between 10 and 100 milligrams per day), the prescription drugs used to treat diabetic hypertension are fraught with more serious and sometimes life-threatening side effects. ACE inhibitors are the most commonly prescribed drug for this condition but they may accelerate kidney failure and may cause a profound drop in blood pressure among diabetics who also take water pills (diuretics). Diuretics are considered first-line treatment of hypertension, but the dose of diuretics must be kept low so as not to cause loss of potassium, sodium and magnesium which could induce irregular heart rhythm. Beta blocking drugs are also employed but there is concern over their usefulness and they may reduce blood flow in peripheral blood vessels. It is obvious the side effects of commonly-used blood pressure lowering drugs are far greater in severity and frequency than the "finger tingling" that occurs with use of high-dose vitamin B6.

It is interesting to note that hydralazine (Apresoline), a drug used to treat hypertension, depletes the body of vitamin B6, magnesium, and potassium, nutrients necessary to maintain healthy blood pressure. So hypertensive patients on this drug will become completely dependent upon its use to maintain blood pressure within the normal range. Hydralazine appears to be designed to make it virtually impossible for a patient to be weaned away from the drug.


It is clear that vitamin B6, taken in doses exceeding 10 milligrams, may help to bring many cases of high blood pressure under control. This may be an unreported reason for the otherwise unexplained effort to limit the dosage of vitamin B6 to no more than 10 milligrams in food supplements. The inclusion of relatively high-dose vitamin B6 into daily multivitamins may significantly reduce the risk for hypertension in the population at large. The widespread use of vitamin B6 would likely reduce health care costs by billions of dollars as well as reduce the risk of side effects associated with commonly prescribed antihypertensive drugs. It is clear that many millions of adults with hypertension could safely self-treat their hypertension with little risk of side effect from vitamin B6. It is unlikely that doctors or pharmaceutical companies would welcome the prevention or self-treatment of hypertension. Even though U.S. health authorities have established a 100-milligram upper limit for vitamin B6 in food supplements, the worldwide harmonization of the dosage of food supplements is now underway via the GATT treaty. Upper dosage limits for vitamin supplements are being negotiated at the upcoming CODEX meetings in Berlin. CODEX could force the U.S. to reduce the upper limit on U.S.-made vitamin B6 supplements in order to comply with fair trade agreements.

Pharmaceutical companies and physicians may have another reason to keep the health benefits of vitamin B6 hidden from the public. Vitamin B6 is necessary for the production of various brain chemicals (serotonin, dopamine, norepinephrine neurotransmitters). Low levels of B6 may be involved in cases of depression. Low B6 levels are commonly found among patients admitted to hospitals for depression. [Lancet, April 18, 1970, pages 832-33] Imagine the fuss should it be found that high-dose vitamin B6 resolves many cases of depression and effectively replaces anti-depressant drugs.

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