Vitamin C Dosing: The Unsung Hero in ADHD Support
- Sara L
- Jan 26
- 7 min read
So is Vitamin C, aka ascorbic acid, important in ADHD?
The short answer is yes.
In ADHD we are running low on dopamine and norepinephrine. Dopamine is important for reward, satisfaction and the desire to form lasting relationships. Norepinephrine is important for helping us feel awake, alert and focused.
When these important brain chemicals run low, we can't pay attention to what is going on around us, we have no drive to push through "boring" tasks and our social relationships begin to suffer.
Interestingly, norepinephrine is made from dopamine. Vitamin C's role in all of this is that it's involved in the step that converts the dopamine to norepinephrine¹. So as you can see, it plays a pretty important role in both helping our brain to produce enough norepinephrine to keep us alert and focused, as well as maintaining the balance between dopamine and norepinephrine. Ultimately we need both to be present to help the brain function optimally. Vitamin C must be obtained from the food we eat or supplements we take: unfortunately, our bodies cannot produce it.
Vitamin C also helps with keeping your child's bowel movements regular and in helping to manage allergies, both of which are often issues seen in ADHD². It also helps the body absorb iron, combating fatigue and anemia.
Vitamin C's anti-inflammatory superpower
Vitamin C acts as an antioxidant, which is especially important in ADHD because of the underlying mitochondrial dysfunction and oxidative stress going on in the background. I covered this topic in a blog post here. In short, mitochondria are found in nearly every cell of the body. They are the tiny power stations located inside cells, producing energy for our bodies. They also produce a waste byproduct in the same way that a factory produces sludge. This sludge waste causes inflammation in the brain. Under normal circumstances this sludge is neutralized by our body's own naturally occurring antioxidants.
Sometimes mitochondria don't work the way they should. This happens in ADHD. This is called mitochondrial dysfunction. Here the excessive production of reactive oxygen species (the sludge) overwhelms the safeguards in place, called antioxidants, which are produced to neutralize them. Neurotypical children are able to produce enough antioxidants to neutralize these reactive oxygen species, but in ADHD, their bodies do not provide enough antioxidants. This is where vitamin C can help. It is a food source of antioxidant that we can ingest to help combat the reactive oxygen species before they cause damage to cells in the brain.
Although the exact cause of ADHD is still unclear, ADHD is thought to be exacerbated by oxidative stress and inflammation³. It is thought that in ADHD, the mitochondria are not working properly.
So all in all, vitamin C is helpful in ADHD for the following reasons:
Helps the body make norepinephrine (more attention, focus and concentration)
Keeps the balance of dopamine and norepinephrine healthy
Helps reduce inflammation
Helps with allergies
Keeps the bowels moving
My child is on a stimulant, which I've heard can stunt their growth.
Does vitamin C help with my child's height overall?
Whilst vitamin C does support the development of healthy bones and collagen there is a theory that it could also assist with helping children grow taller, or at least allowing them to reach the full potential of what their height should be based on their genetics. Conversely, a malnourished child is unlikely to reach their full adult height. This is especially important in children with ADHD who are taking stimulants.
Stimulants are thought to result in a "modestly" reduced height in childhood, though the effects are not thought to be permanent and children are thought to eventually make up the "lost" height in adulthood, once treatment with the stimulant is discontinued⁴.
Adding vitamin C to a child's diet provides them with additional supplementation of this micronutrient to help mitigate, though likely not fully prevent, the "modest" height reduction expected when taking stimulant medications.
Ok, should my child take vitamin C, or any vitamin C containing products while they are also taking a stimulant medication?
They certainly can. However they should not take vitamin C at the same time as an amphetamine stimulant, such as Adderall, Dyanavel or Vyvanse. Anything containing vitamin C should be taken one hour before or after taking an amphetamine. This is because vitamin C will react with the amphetamine and produce a salt compound that your body cannot use. Therefore the stimulant will not be able to be absorbed by the body. So no citrus fruits, or any other products that contain vitamin C / ascorbic acid right before or after taking an amphetamine-based medication.
This doesn't happen with methylphenidate-based medications such as Ritalin, Concerta or Focalin.
Dosing
Ideally vitamin C is taken on its own instead of as part of a multi-vitamin. The reason is that, as part of a multivitamin, it is going to be impossible for you to adjust the dose of the vitamin C alone, as it is bound up with many other vitamins and minerals.
There was a study that looked at vitamin C mixed with flax seed oil, which is high in a type of omega-3 fat called ALA that you may have heard of. (As opposed to DHA and EPA that we normally use in ADHD support). The results from the study revealed significant improvements in ADHD symptoms⁵. This suggests that vitamin C might be most effective as part of a comprehensive nutritional approach rather than as a standalone treatment. Please feel free to read my article on omega supplementation in ADHD here to learn more about how to incorporate omega-3 into your child's daily routine.
Dosages for Vitamin C
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 & Nutrition Board. These RDA values are based on meeting the nutrient requirements of 97 to 98% of "healthy individuals" without the metabolic and nutritional complexities of ADHD. The Food & Nutrition Board acknowledges that the RDAs that they recommend are not intended for individuals with specific health conditions, like ADHD (Godbout Laake & Compart, 2013).
In addition, the RDAs are the amounts recommended from all sources: food and supplements. Children with ADHD may be getting a lot less vitamin C from food compared to their neurotypical friends, due to impulsive and unhealthy eating habits with a possible preference for processed and packaged snacks and meals, due to dopamine seeking-behaviors. They are going to require higher doses of supplementation compared to their neurotypical friends.
I have provided the RDA values for vitamin C below for reference so that you can see the dosing recommendation for "healthy" individuals, and compare it to the dosing recommendations for ADHD that follow.
RDAs for "healthy individuals" for vitamin C⁶
Age | Male (mg) | Female (mg) |
1–3 years | 15 | 15 |
4–8 years | 25 | 25 |
9–13 years | 45 | 45 |
14–18 years | 75 | 65 |
19+ years | 90 | 75 |
The ADHD and Autism Nutritional Supplement handbook (Godbout Laake & Compart, 2013) suggests dosages in the table below for vitamin C. Again these doses are much higher than what you see in the RDA table above, highlighting the differing daily requirements of children with ADHD compared to neurotypical children. Children with ADHD typically have more inflammation, oxidative stress and problems with their immune system, which vitamin C can help with.
Age | Dose (mg) | Frequency |
2–5 years | 100–250 | 1–2 times per day |
6–10 years | 500 | 1–2 times per day |
11+ years | 500–1000 | 1–2 times per day |
(The dosage is total per day, not per dose. I.e. if taking twice per day, only take half the daily dose each time.)
Is there a specific type of vitamin C that my child should take?
Supplemental ascorbic acid (vitamin C) has equivalent bioavailability to that of naturally occurring ascorbic acid you may find in citrus fruits⁶. This means it is as easy for the body to use as the vitamin C found naturally occurring in food. Buy ascorbic acid on its own as this allows you to manipulate the dose without inadvertently increasing the dose of whatever else might be included in a combined dual- or multi-vitamin supplement. I like products by Pure Encapsulations as they are third-party tested for purity.
For older kids the 1000mg capsules are a good option here. For younger kids Nordic naturals does a 250mg gummy here, or you could consider Kirkman Labs capsules which you can open and sprinkle into apple sauce or yogurt if you want to avoid the sugar associated with gummies.
Toxicity and side effects⁶
Vitamin C is considered relatively safe and is not thought to be toxic in high doses.
But high doses may cause these side effects:
Diarrhea
Nausea
Abdominal cramps
Iron overload in the body
Medications your child may be taking that vitamin C interacts with:
Statins
Chemotherapy and radiation
People at risk of adverse outcomes with high doses of vitamin C: People with hemochromatosis.
Summary
Vitamin C, or ascorbic acid, plays a crucial role in supporting brain function and overall health in children with ADHD. It helps convert dopamine to norepinephrine, essential for attention, focus, and maintaining emotional balance, while also reducing brain inflammation and oxidative stress caused by mitochondrial dysfunction. For children taking stimulant medications, vitamin C may help support healthy growth, although it should not be consumed at the same time as amphetamine-based stimulants like Adderall, as it can interfere with absorption. Higher doses of vitamin C are often recommended for children with ADHD due to increased inflammation, oxidative stress, and dietary challenges. Suggested doses range from 100–1000 mg daily, depending on age. Overall, vitamin C offers significant benefits when taken as part of a comprehensive nutritional approach tailored to the needs of children with ADHD.
If you're considering supplementation, it's always best to chat with your healthcare provider first. They can help you determine the right dosage and whether it's appropriate for your specific situation. And remember, a balanced diet rich in vitamin C is a great place to start!
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.
²Godbout Laake, D. & Compart, P. J. MD (2013) The ADHD and Autism Nutritional Supplement Handbook. Fair Winds Press.
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