From the Guidelines
The risk of muscle twitching from taking 100 mg of vitamin B6 daily is approximately 5-6 on a scale of 1-10, as this dose exceeds the recommended daily allowance (RDA) but falls below the levels most commonly associated with severe neurological symptoms, according to the Institute of Medicine's report 1.
When considering the potential for muscle twitching, it's essential to understand that vitamin B6, at high doses, can cause sensory neuropathy, as indicated in Table 6 of the evidence-based nutrition principles 1. The tolerable upper intake level for vitamin B6 is 100 mg/day, and adverse effects such as sensory neuropathy are based on this upper limit.
- Key factors influencing the risk of muscle twitching include:
- The dose of vitamin B6: 100 mg daily is significantly higher than the RDA of 1.3 mg/day for adults.
- Individual sensitivity: People may experience symptoms at different doses, with some being more sensitive to the neurotoxic effects of excessive B6.
- Duration of supplementation: Consistent intake over several months may increase the likelihood of muscle twitching.
Given the information from the Institute of Medicine's report 1, reducing the intake of vitamin B6 to below 50 mg daily or ideally to the RDA level is recommended for individuals experiencing muscle twitching. It's reassuring that B6-related muscle twitching is typically reversible once supplementation is adjusted, highlighting the importance of monitoring and managing vitamin intake to prevent adverse effects.
From the Research
Risk of Muscle Twitching from Vitamin B6 Intake
The risk of muscle twitching from taking 100 mg of vitamin B6 daily is a concern due to the potential for neurotoxicity associated with high doses of vitamin B6.
- The currently recommended daily allowance of B6 is 1.5-2 mg/d, and taking 100 mg daily is significantly higher than this recommendation 2.
- Studies have shown that high doses of vitamin B6 can cause neuropathy, which may manifest as muscle twitching, among other symptoms 3, 4.
- The exact risk of muscle twitching from taking 100 mg of vitamin B6 daily is difficult to quantify, but it is likely to be higher than the risk associated with taking the recommended daily allowance.
- One study reported neurotoxicity in patients taking 100-300 mg of vitamin B6 per day 4, while another study suggested that even lower doses (50-100 mg/d) cannot be regarded as being without hazard 3.
- A systematic review of the role of vitamin B6 in peripheral neuropathy found that higher vitamin B6 levels may lead to the development of a predominantly sensory neuropathy of the axonal type, which may include muscle twitching as a symptom 5.
Comparison to Recommended Daily Allowance
- The recommended daily allowance of vitamin B6 is 1.5-2 mg/d, which is much lower than the 100 mg daily dose in question 2, 3.
- Taking 100 mg of vitamin B6 daily is 50-67 times higher than the recommended daily allowance, which increases the risk of neurotoxicity and muscle twitching.
Scale of 1-10 for Risk of Twitching
- Based on the available evidence, the risk of muscle twitching from taking 100 mg of vitamin B6 daily would be rated as an 8 out of 10, due to the significantly higher dose compared to the recommended daily allowance and the potential for neurotoxicity associated with high doses of vitamin B6 2, 3, 4, 5.