Vitamin A
What is Vitamin A?
Vitamin A is a fat-soluble vitamin that is vital for our vision, immune system, and gut microbiome. Research reveals low levels of vitamin A are consumed in autism, higher levels of deficiencies are seen in ASD, and supplementation may improve autistic symptoms and metabolic processes.
Vitamin A can be found within the diet two ways: (1) pre-formed vitamin A or (2) pro-vitamin A carotenoids. There are three different provitamin A carotenoids, but the most important and popular form is beta-carotene. Pre-formed vitamin A can be found in animal products. [1]
Beta-carotene is the orange pigment that gives carrots both their name and color!
Since vitamin A is fat-soluble, it is absorbed along with fat into the cells within the small intestine. Vitamin A can then be stored in the liver. [1]
Children with autism consume less vitamin A [2] and have more vitamin A deficiencies than typically developing children [3-4]
Supplementation with vitamin A is shown to improve autistic symptoms and metabolic processes [4]
Food Sources of Vitamin A
Pre-formed vitamin A can be found in many animal sources, but it is found in the highest concentrations within animal livers and fish oils. Some animal sources can include both pre-formed vitamin A and a small amount of pro-vitamin A. Examples include:
Liver
Meat & poultry
Pro-vitamin A (ex: beta-carotene) can be abundantly found in plants. Examples include:
Red/orange/yellow fruits & vegetables, such as:
Sweet potatoes & yams
Carrots
Bell peppers
Tomato products
Dark leafy vegetables
Broccoli
Some vegetable oils
Recommended Intake
These recommendations are based off of the Recommended Dietary Allowance (RDA), which is the average daily level of intake sufficient to meet the nutrient recommendations of nearly all (97-98%) of healthy individuals. Since each form of vitamin A has different bioavailability, its RDA is given as Retinol Activity Equivalents (RAE).
Males
o-6 months: 400 mcg
7-12 months: 500 mcg
1-3 years: 300 mcg
4-8 years: 400 mcg
9-13 years: 600 mcg
14-18 years: 900 mcg
19-50 years: 900 mcg
51+ years: 900 mcg
Females
o-6 months: 400 mcg
7-12 months: 500 mcg
1-3 years: 300 mcg
4-8 years: 400 mcg
9-13 years: 600 mcg
14-18 years: 700 mcg
19-50 years: 700 mcg
51+ years: 700 mcg
Deficiency
Vitamin A deficiency is rare within the United States. Deficiency is most likely to happen to those who don’t consume sufficient amounts of meat products (sources of pre-formed vitamin A) or red/orange fruits and vegetables (sources of beta-carotene).
Common symptoms of vitamin A deficiency include:
Night blindness
Inability to see in low light
Bitot spots in the eye (a grey or white lesion in the white of the eye)
Increased severity of infections such as diarrhea and measles.
Individuals at increased risk of Vitamin A deficiency include:
Picky or selective eaters who won’t eat fruits and/or vegetables
Individuals on restrictive diets
Preterm infants
Individuals with cystic fibrosis
Toxicity
Vitamin A is fat-soluble, meaning that it can be stored better within the body (specifically within the liver), which can be toxic if consumed in excess long-term. An overdose of vitamin A from animal products (like liver) and supplements can be toxic, but large doses of beta-carotene (from fruits & vegetables) is not known to be harmful. In fact, if you ever noticed your baby’s skin turn orange after eating large amounts of carrot baby food, you’ve seen it!
If someone did consume excessive vitamin A for a long period of time, it could lead to dizziness, nausea, headaches, skin irritation, joint pain, coma and even death. Remember: this kind of toxicity can only be caused by an overdose of retinol, either from supplements or by eating excessive amounts of animal liver. Eating large amounts of foods containing beta-carotene such as carrots or other plant-based foods will not have this effect.
Upper limits for pre-formed vitamin A have been established due to the concern for liver damage that can occur. There is no upper limit specifically for beta-carotene and other provitamin A sources. The Tolerable Upper Intake Level (UL) is the maximum daily intake unlikely to cause adverse health effects.
Upper Limits of Vitamin A
Males & Females
0-12 months: 600 mcg
1-3 years: 600 mcg
4-8 years: 900 mcg
9-13 years: 1700 mcg
14-18 years: 2800 mcg
19-50 years: 3000 mcg
Supplements
Dietary supplements for vitamin A come in many different forms. They can come as a part of a multivitamin, or just as vitamin A. Some supplements will contain only beta-carotene or only preformed vitamin A, while others will have a combination of both. The supplements will tell you the amount and the percentage of each on the supplement facts label.
Examples:
Note: All supplements are linked to Amazon for convenience, however, buying supplements on Amazon does not guarantee quality, as there are many “unverified resellers” selling nutrition supplements. To buy supplements that are verified to be sent directly to the consumer, you can create an account on the Autism Dietitian FullScript and search for the respective supplement under “Catalog”.
DISCLAIMER: Before starting any supplement or medication, always consult with your healthcare provider to ensure it is a good fit for your child. Dosage can vary based on age, weight, gender, and current diet.
Vitamin A & Autism in the Research
Deficiency
Children with autism consume less vitamin A than typically developing children [2]
Children with autism have more vitamin A deficiencies than typically developing children [3-4]
Autism Severity
Vitamin A deficiency is linked to increased typical autism symptoms, and as the severity of the deficiency worsens so do the symptoms [3-4]
Supplementation of vitamin A is shown to improve autistic symptoms and metabolic processes [4]
Gut Microbiome
Vitamin A plays an important role in changes in autism biomarkers [5]
Decreased vitamin A levels in the body, both prenatally and in the gut, showed a correlation with increased risk of autism [6]
Maternal Vitamin A
Vitamin A deficiency during gestation might be a risk factor for autistic-like behaviors. Improvements were seen with vitamin A supplementation during early-life in a rat model [7]
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[1] Debelo H, Novotny JA, Ferruzzi MG. Vitamin A. Adv Nutr. 2017;8(6):992-994.
[2] Bjørklund G, Waly MI, Al-farsi Y, et al. The Role of Vitamins in Autism Spectrum Disorder: What Do We Know?. J Mol Neurosci. 2019;67(3):373-387.
[3] Guo M, Zhu J, Yang T, et al. Vitamin A and vitamin D deficiencies exacerbate symptoms in children with autism spectrum disorders. Nutr Neurosci. 2019;22(9):637-647.
[4] Guo M, Zhu J, Yang T, et al. Vitamin A improves the symptoms of autism spectrum disorders and decreases 5-hydroxytryptamine (5-HT): A pilot study. Brain Res Bull. 2018;137:35-40.
[5] Liu J, Liu X, Xiong XQ, et al. Effect of vitamin A supplementation on gut microbiota in children with autism spectrum disorders - a pilot study. BMC Microbiol. 2017;17(1):204.
[6] Maes M, Anderson G, Betancort medina SR, Seo M, Ojala JO. Integrating Autism Spectrum Disorder Pathophysiology: Mitochondria, Vitamin A, CD38, Oxytocin, Serotonin and Melatonergic Alterations in the Placenta and Gut. Curr Pharm Des. 2019;25(41):4405-4420.
[7] Lai X, Wu X, Hou N, et al. Vitamin A Deficiency Induces Autistic-Like Behaviors in Rats by Regulating the RARβ-CD38-Oxytocin Axis in the Hypothalamus. Mol Nutr Food Res. 2018;62(5)
