Part 3: B6 for Autism Spectrum Disorder
- Sara L
- Mar 3, 2024
- 4 min read
Vitamin B6 is used by the body to produce chemicals that the brain needs to function, chemicals such as GABA and Serotonin. GABA is a relaxation chemical and Serotonin is a well-being chemical.
In ASD the levels of GABA and serotonin are not what they should be causing some behavioral symptoms of ASD. B6 appears to be widely used to help lessen symptoms of ASD¹ and is touted as helping up to half² of children with ASD in terms of lessening these behavioral issues. These results were based on parent reports, and we not objectively measured, so it's difficult to say how accurate they are.
Despite this, supplementation with B6 is thought to restore levels of these important brain chemicals and help lessen symptoms of ASD.
Potential benefits of supplementation
But what type of B6 is best?
Pyridoxine is the most common form of B6 that you will find at the pharmacy.
In order for the body to use it it must first be turned into Pyridoxal 5 Phosphate (P5P). This is the ‘active’ form that the body can use. P5P is made in the Liver from B6.
However some people cannot convert B6 (Pyridoxine) to Pyridoxal 5 Phosphate (P5P). This is true in Autism³ with studies showing that Children with Autism are unable to convert B6 to the P5P that their bodies can use. This causes high levels of B6 to build up in their bodies as it cannot be converted into P5P⁴. Therefore it is best to give them P5P, the already active form of B6, to ensure that their brains and bodies are able to fully use this nutrient to make the good brain chemicals they need.
B6 dosages
A word on the Recommended Daily Allowances (RDAs) numbers. These guidelines were established by The Institute of Medicine of the National Academies as well as the Food and Nutrition Board (FNB). These RDA values are based on meeting the nutrient requirements of 97 to 98% of ‘healthy individuals’ without the metabolic and nutritional complexities of ASD leading to malnutrition. The Food and Nutrition Board acknowledges that the RDAs that they recommend are not intended for individuals with specific health conditions, like ASD (Godbout Laake & Compart, 2013).
Children with ASD are going to require higher doses of supplements compared to their neuro typical friends. Therefore I do not consider the RDAs helpful for our purposes.
However I will provide them here for reference so you get an idea of what would be considered 'normal' doses of B6. As you can see below, dosages for ‘healthy’ children hover around 1 gram.
Recommended Dietary Allowance (RDAs)⁵
Age | Dose (mg) |
1-3 years | 0.5 |
4-8 years | 0.6 |
9-13 years | 1.0 |
14-18 years | 1.3 |
19-50 years | 1.3 |
What is the highest amount of B6 you can safely take?
In 2023, the Panel on Nutrition, Novel Foods and Food Allergens of the European Food Safety Authority (EFSA) released their numbers for Tolerable Upper Intake Levels for vitamin B6.
A Tolerable Upper Intake Level is the highest level of a nutrient that can safely be taken without causing adverse side effects.
Their doses for children ranged from 2.2 to10.7 mg/day for children, depending on age⁶.
Now, let’s compare that to the Tolerable Upper Intake Levels by the US FNB below.
Tolerable Upper Intake Levels for B6⁷
Age | Dose (mg) |
1-3 years | 30 |
4-8 years | 40 |
9-13 years | 60 |
14-18 years | 80 |
19-50 years | 100 |
As you can see from the table above the US FNB Upper limits are around 10x higher than the European limits.
This could be due to many factors such as the Europeans updating their numbers much more recently than the US, and culturally being more conservative with medication dosing overall.
But how do you convert dosing from B6 to P5P?
So in terms of actual dosing for P5P in ASD, it’s a little bit messy.
P5P is considered more potent than B6, so will be given at a lower dose than those seen in the two tables above (Godbout Laake & Compart, 2013).
These two authors recommend B6 and P5P dosing as shown below. The P5P dosing bolded is the most useful to us.
Age (years) | B6 (mg) | P5P (mg) |
2-5 | 10 - 15 | 5 |
6-10 | 20 - 30 | 10 |
11+ | 50 | 15 |
How to start with B6 dosing
You would want to start low with P5P, and then slowly build up to the number provided in the above table by Godbout Laake & Compart (2013).
At this point in time I advise against going higher than the FNB's Tolerable Upper Levels discussed as too much B6 can actually decrease the amount of P5P the body can make, so it would have the opposite effect and drive P5P levels down⁸ in children with ASD who already naturally have low levels of P5P thanks to their problems converting B6 to P5P.
Toxicity and Side Effects
Supplementation with B6 is generally safe, even up to doses of up to 200mg/day, but again I recommend staying below that. Beyond 200mg you might start to risk toxicity and causing numbness of the skin.
Before starting B6, make sure to talk to your child's provider so that they are able to guide you and monitor your child.
Side effects to look out for: tummy pain, nausea, headache, loss of appetite.
Toxicity: Numbness of skin, problems with walking due to imbalance, irritability, inability to hold urine, sensitivity to light⁹.
Medications your child may be taking that B6 interacts with:
Cycloserine (used to treat TB) decreases B6 levels in the body. Discuss with your childs healthcare provider if increasing B6 is a good idea to combat this effect.
Anti seizure medications like Valproic acid, carbamazepine and phenytoin. B6 can make them less effective.
Theophylline can decrease B6 levels and cause seizures as a result.
In the PDF here that I have attached, I have provided a Cheat Sheet for Moms with a summary of B6's characteristics discussed above, as well as a ‘cut the dotted line’ section for when it comes time to shop for B6 with steps and recommendations to keep in mind when purchasing including checking for third party testing to ensure that what you are buying is high quality.
This site is for general informational purposes only and does not constitute the giving of medical advice. The contents do not constitute the practice of medicine, nursing, or other professional health care services. No provider–patient relationship is formed. Please consult with your child's healthcare provider when considering supplementation for children.
Godbout Laake, D. & Compart, P. J. MD (2013) The ADHD and Autism Nutritional Supplement Handbook. Fair Winds Press. To purchase on Amazon click here.
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