What Is Vitamin B6? Understanding Its Role, Side Effects and Safe Use

Vitamin B6 has come under some scrutiny recently following a media report about a number of patients suffering adverse consequences from excessive supplementation. In this blog, we’ll take a more detailed look at this key nutrient, why toxicity occurs, examine potential side effects of excessive supplementation and highlight how to ensure you’re consuming safe levels of B6.

What Is Vitamin B6?

Vitamin B6, also known as pyridoxine, is a water-soluble vitamin that plays a vital role in numerous physiological functions. It is essential for brain development, immune function, and metabolism. Vitamin B6 helps the body produce neurotransmitters such as serotonin and dopamine, which regulate mood and cognitive function. It also assists in forming haemoglobin, the protein in red blood cells responsible for carrying oxygen throughout the body.

Since the human body does not store large amounts of Vitamin B6, it must be obtained from dietary sources, including:

• Poultry and fish (such as chicken, turkey, and salmon)
• Bananas and potatoes
• Legumes and nuts

Most people can meet their Vitamin B6 needs through a balanced diet. However, some individuals may require supplementation due to certain health conditions, chronic stress, pregnancy or specific dietary restrictions.

While Vitamin B6 is crucial for health, recent media coverage has raised concerns about toxicity from excessive supplementation. High doses of Vitamin B6, typically from some supplements, energy drinks, protein shakes and even some cereals, can lead to adverse side effects, including:

• Peripheral Neuropathy (nerve damage): Long-term excessive intake can cause numbness, tingling or pain in the hands and feet, leading to difficulty walking.
• Sensory disturbances: Some individuals experience changes in their ability to feel pain or temperature.
• Gastrointestinal issues: Nausea and abdominal discomfort can occur with high-dose supplementation.
• Photosensitivity: Increased sensitivity to sunlight can result in skin reactions.

It is important to note that Vitamin B6 toxicity is rare and usually associated with prolonged intake of excessive doses.

Understanding Vitamin B6 Toxicity: Why It Happens and What You Need to Know

Like all nutrients, there’s a fine balance between getting enough and consuming too much. So, what happens if you take too much vitamin B6, and how does it turn toxic?

Why Does Vitamin B6 Cause Toxicity?

The first thing to understand is that every nutrient has two sides: the risk of deficiency and the risk of toxicity. The body is designed to function optimally when nutrients are balanced – not too little, not too much. Water-soluble vitamins like B6 usually leave the body within a day, meaning we need to replenish them regularly. However, vitamin B6 is a bit unique in how it behaves, and this is where toxicity can occur.

Typically, people think of vitamin B6 toxicity in extreme cases of very high doses, such as 500 milligrams or more per day over extended periods. This is the kind of scenario where neurotoxicity – affecting your nerves – becomes a problem. But here’s the twist: even when taking moderate or recommended doses, some individuals can still experience toxicity due to how their body metabolises B6.

The Complexity of Vitamin B6 Metabolism

Unlike other vitamins, vitamin B6 isn’t just one compound; it has several different forms, each of which can take different metabolic pathways. For example, one of the active forms of B6, called pyridoxal-5-phosphate (P5P), is often given as a supplement for its bio-availability. However, even this “active” form has many routes it can take to be metabolised. Some of these pathways can create compounds that are more damaging to your nervous system, particularly under certain conditions like inflammation or oxidative stress.

This is where inflammation plays a critical role. When B6 is metabolised in the presence of inflammation, it can produce forms of the vitamin that have a more detrimental effect on the nervous system. Inflammatory conditions like smoking, chronic illness or genetic predispositions can make this process worse. It’s not just about how much B6 you’re taking – it’s about how your body is handling it.

Why Do Some People Experience Toxicity and Others Don’t?

Not everyone reacts to B6 the same way. You could have 1,000 people taking vitamin B6, and most would never experience toxicity. But the 1,001st person might. Why? It often comes down to genetics, inflammatory conditions, and how your body metabolises the vitamin. Some people have genetic variants (called single nucleotide polymorphisms, or SNPs) or enzyme imbalances that make their bodies process B6 differently, leading to the buildup of neurotoxic forms.

For these individuals, the root cause of toxicity isn’t necessarily the vitamin itself, but how the body is metabolising it in the context of an underlying inflammatory or genetic issue. In other words, if you have B6 toxicity, it’s not always the vitamin that’s the problem—it’s the inflammatory response that happens when B6 is metabolised inappropriately.

What Can You Do About It?

If you’re experiencing B6 toxicity, the first step is to stop taking supplemental B6 until you’ve addressed the underlying issue. However, removing B6 alone won’t solve the problem long term. You’ll need to focus on addressing any inflammation or metabolic issues that could be causing your body to handle B6 differently. This could involve lifestyle changes, nutritional interventions or even looking deeper into genetic predispositions.

The Misleading Nature of B6 Blood Tests

If you’ve had a blood test that shows high B6 levels, it’s important to know that the test may not be as reliable as you think. Vitamin B6 exists in several forms, and these tests measure all of them in a pool. The test doesn’t differentiate between the forms that might be harmful to your nerves and the forms that are beneficial. 

While an elevated B6 result can point you in the right direction, it doesn’t give you a complete picture. The real issue lies in how your body metabolises B6, which is why you need to focus on addressing the underlying inflammatory conditions rather than just the numbers on a lab report.

What to Do Next

If you suspect B6 toxicity, the most important thing is to remove excess B6 from your diet and supplements. But don’t stop there – look deeper at your overall health. Are there any inflammatory conditions like chronic illness, poor antioxidant balance, or lifestyle factors (such as smoking) at play? Are there any genetic factors that could make your body process nutrients differently?

By addressing the root causes of inflammation and working with a healthcare professional to manage your B6 intake, you can regain balance and avoid toxicity.

How to Take Vitamin B6 Safely

To ensure the safe and effective use of Vitamin B6, follow these guidelines:

• Consult a healthcare professional: a qualified nutritionist, naturopath or GP can test whether you require supplementation and prescribe the appropriate dosage.
• Only supplement when necessary: Those with diagnosed deficiencies, certain medical conditions, or increased needs (e.g., pregnancy) may require supplementation under professional guidance.
• Stick to recommended dosages: Avoid exceeding the TGA-recommended upper limits unless prescribed by a healthcare professional.
• Monitor for side effects: If you experience symptoms like numbness, tingling or other neurological issues, discontinue high-dose supplements and seek medical advice.
• Get Vitamin B6 from food first: A well-balanced diet typically provides adequate amounts of Vitamin B6 without the risk of toxicity.

Conclusion

Vitamin B6 is an essential nutrient, but like all nutrients, it must be balanced properly. While toxicity from B6 is rare, it can occur, especially in individuals with certain genetic or inflammatory conditions. The key to preventing B6 toxicity is understanding how your body metabolises it and addressing any underlying issues that could cause a harmful buildup. 

While Vitamin B6 plays a critical role in health, not everyone needs to take a supplement. Consulting a qualified nutritionist, naturopath or healthcare professional can help determine if supplementation is necessary based on your diet, lifestyle and individual health requirements.

At Perpetual Wellbeing, we take a holistic approach to health, ensuring that any supplements you take are tailored to your specific needs. We offer general and functional pathology testing to determine when supplementation is required and prescribe safe and appropriate doses tailored to your specific needs. If you have concerns about your Vitamin B6 levels or are experiencing potential side effects, book a consultation with our team today.