Unfortunately, even though B6 is water soluble, it can have toxic neurological effects if too much is taken over time. Cases of toxicity as a result of supplementation are well-documented. I myself have had a client who suffered from what appeared to be peripheral neuropathy, and those symptoms all but disappeared after B6 supplementation was eliminated. There is a lot of research on this, but here is a brief excerpt from a fairly comprehensive Wikipedia article on the topic:

“Adverse effects have only been documented from vitamin B6 supplements and never from food sources. This article only discusses the safety of the common supplemental form of vitamin B6 pyridoxine (for a full discussion please see pyridoxine). Toxicologic animal studies identify specific destruction of the dorsal root ganglia[16] which is documented in human cases of overdosage of pyridoxine.[17] Although vitamin B6 is a water-soluble vitamin and is excreted in the urine, doses of pyridoxine in excess of the RDI over long periods of time thus result in painful and ultimately irreversible neurological problems.

The primary symptoms are pain and numbness of the extremities, and in severe cases difficulty walking. Sensory neuropathy typically develops at doses of pyridoxine in excess of 1,000 mg per day. However, there have been a few case reports of individuals who developed sensory neuropathies at doses of less than 500 mg daily over a period of months. None of the studies, in which an objective neurological examination was performed, found evidence of sensory nerve damage at intakes of pyridoxine below 200 mg/day. This condition is usually reversible when supplementation is stopped.[18]

Existing authorizations and valuations vary considerably worldwide. In 1993 the European Community Scientific Committee on Food defines intakes of 50 mg vitamin B6 per day as harmful and established tolerable upper intake level of 25 mg/day for adults in 2000.

The Expert Group on Vitamins and Minerals of the Food Standard Agency UK (UK EVM) derived a safe upper level (SUL) of 10 mg/day for a 60 kg adult in 2003.

The tolerable upper limit has been set by the US FDA at 100 mg/day in 2000.[19] The nutrient reference values in Australia and New Zealand recommend an upper limit of 50 mg a day in adults.”

Till next,
–T.Collins Logan