Vitamin C

What is Vitamin C?

  • Vitamin C, or ascorbic acid, is important for immune function, neurotransmitter and collagen production, as well as antioxidant status. Vitamin C deficiency has been documented clinically in children with autism with severely selective diets.

  • Vitamin C is a water soluble nutrient that can be found naturally within foods and as a dietary supplement. The body is not able to make vitamin C within the body, so it must be consumed from the diet. 

  • Vitamin C is crucial for helping our body make collagen (part of connective tissue and important for wound healing), L-carnitine and certain neurotransmitters. Vitamin C also helps with protein metabolism.

  • A commonly known role that vitamin C plays is as an antioxidant within the body and helping regenerate other antioxidants like vitamin E. Current research is being done to see the effectiveness of vitamin C, with its antioxidant properties, for reducing oxidative stress. Lastly, vitamin C helps non-heme iron (iron from plant sources) to be absorbed. 

  • On average, 70%-90% of moderate intakes of vitamin C is absorbed. Excess urine from high dosages is excreted in the urine, due to it being a water-soluble vitamin. 

  • Vitamin C deficiency, or scurvy, is thought to be a rare nutrient deficiency, however we still see it clinically in children with autism with severely selective diets. [1-6]

Food Sources of Vitamin C


Recommended Intake

These recommendations are based on 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.

Males

  • 1-3 years: 15 mg/day

  • 4-8 years: 25 mg/day

  • 9-13 years: 45 mg/day

  • 14-18 years: 75 mg/day

  • 19+ years: 90 mg/day

Females

  • 1-3 years: 15 mg/day

  • 4-8 years: 25 mg/day

  • 9-13 years: 45 mg/day

  • 14-18 years: 65 mg/day

  • 19+ years: 75 mg/day



Deficiency

Vitamin C deficiency leads to a disease state called scurvy. How long it takes to reach scurvy after vitamin C intake becomes inadequate depends on each individual. Typically, symptoms will appear within 1 month of little to no vitamin C intake. Symptoms can occur if intake is <10mg/day for many weeks. 

Signs of Scurvy Include: 

  • Fatigue

  • Malaise

  • Inflammation of the gums (may include swelling and/or bleeding)

  • Unexplained limp

  • Connective tissue weakens causing 

    • Tiny round, brown-purple spots due to bleeding under the skin called Petechiae

    • Discoloration of the skin or easy bruising (Ecchymoses)

    • A rash of purple spots due to leaking small blood vessels called purpura

    • Joint pain

    • Poor wound healing

    • Thickening of the skin, called hyperkeratosis

    • Corkscrew hairs

  • Loss of teeth

  • Iron deficiency

  • Bone disease in children

Individuals at Risk of Inadequacy Include: 

  • Individuals with low fruit/vegetable intake

  • Individual with restricted diets or overall poor intake

  • Smokers

  • Infants fed evaporated or boiled milk

  • Individuals with limited food variety

  • Individuals with malabsorption and certain chronic diseases such as cancer or end-stage renal disease on chronic hemodialysis

Toxicity

Vitamin C is not seen to cause any adverse health effects from large doses. The most common complaints from high doses include nausea, diarrhea, abdominal cramps, and other gastrointestinal issues. 

Some studies have shown adverse effects of high doses of vitamin C, but none have been verified and/or have conflicting research. More research needs to be done to see if high doses of vitamin C will have an effect on any of the following conditions: 

  • Vitamin C causing kidney stones in people with existing kidney issues

  • Hereditary hemochromatosis

  • Increased risk of cardiovascular disease in postmenopausal women with diabetes

  • Vitamin C may cause chromosomal and/or DNA damage and could contribute to cancer

  • Reduce vitamin B12 and copper levels in the body

  • Erosion of dental enamel

  • Allergic responses

Males & Females

  • 1-3 years: 400 mg/day

  • 4-8 years: 650 mg/day

  • 9-13 years: 1200 mg/day

  • 14-18 years: 1800 mg/day

  • 19+ years: 2000 mg/day

Supplements

Dietary supplements typically come in the form of ascorbic acid, which has the same ability to be absorbed as ascorbic acid from foods.

Vitamin C is water-soluble, which can affect its absorption. Liposomal (or fat-soluble) vitamin C is available, which increases absorption significantly and may have additional therapeutic benefits. “Buffered” vitamin C means that it has been combined together with buffering minerals such as magnesium, potassium, or calcium to consume higher levels without causing stomach upset.

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.

Research

 

Vitamin C & Autism in the Research

Scurvy Due to Picky Eating

  • Vitamin C deficiency (scurvy) is seen within individuals with autism or other neurologic conditions. The most common presenting symptom was an unexplained limp. [1-6]

  • Three children with ASD who presented with refusal to walk and gingivitis who underwent comprehensive evaluations before establishing the diagnosis of vitamin C deficiency (scurvy). The symptoms resolved after treatment with vitamin C. [1]

  • Case study: A 17-year-old male with autism spectrum disorder and a diet severely deficient in ascorbic acid due to textural aversion and food preferences. He presented with recurrent arthritis, hemarthrosis, bruising, and anemia. His vitamin C level was low, and his symptoms improved promptly after treatment with ascorbic acid. [7]

Vitamin C Intake

  • Children with autism often have restricted diets from a number of reasons. Vitamin C deficiency is possible when the diet is restricted. [3]

  • Children with autism typically consume less vitamin C than typically developing children. [8]

Vitamin C Supplementation

  • Research shows that vitamin C can be beneficial for sensorimotor behaviors and can reduce autism severity behavior. [8]


  • [1] Swed-Tobia R, Haj A, Militianu D, Eshach O, Ravid S, Weiss R, Aviel YB. Highly Selective Eating in Autism Spectrum Disorder Leading to Scurvy: A Series of Three Patients. Pediatr Neurol. 2019 May;94:61-63. doi: 10.1016/j.pediatrneurol.2018.12.011. Epub 2018 Dec 28. PMID: 30795887.

    [2] Gulko E, Collins LK, Murphy RC, Thornhill BA, Taragin BH. MRI findings in pediatric patients with scurvy. Skeletal Radiol. 2015 Feb;44(2):291-7. doi: 10.1007/s00256-014-1962-y. Epub 2014 Aug 12. PMID: 25109378.

    [3] Ma NS, Thompson C, Weston S. Brief Report: Scurvy as a Manifestation of Food Selectivity in Children with Autism. J Autism Dev Disord. 2016 Apr;46(4):1464-70. doi: 10.1007/s10803-015-2660-x. PMID: 26590972.

    [4] Golriz F, Donnelly LF, Devaraj S, Krishnamurthy R. Modern American scurvy - experience with vitamin C deficiency at a large children's hospital. Pediatr Radiol. 2017 Feb;47(2):214-220. doi: 10.1007/s00247-016-3726-4. Epub 2016 Oct 24. PMID: 27778040.

    [5] Niwa T, Aida N, Tanaka Y, Tanaka M, Shiomi M, Machida J. Scurvy in a child with autism: magnetic resonance imaging and pathological findings. J Pediatr Hematol Oncol. 2012 Aug;34(6):484-7. doi: 10.1097/MPH.0b013e318236c519. PMID: 22258350.

    [6] Andrews SL, Iyer S, Rodda C, Fitzgerald J. Scurvy: A rare cause for limp in a child with autism spectrum disorder. J Paediatr Child Health. 2018 Dec;54(12):1375-1377. doi: 10.1111/jpc.14098. Epub 2018 Jun 27. PMID: 29947447.

    [7] Amos LE, Carpenter SL, Hoeltzel MF. Lost at Sea in Search of a Diagnosis: A Case of Unexplained Bleeding. Pediatr Blood Cancer. 2016 Jul;63(7):1305-6. doi: 10.1002/pbc.25980. Epub 2016 Apr 8. PMID: 27062477.

    [8] Bjørklund G, Waly MI, Al-Farsi Y, Saad K, Dadar M, Rahman MM, Elhoufey A, Chirumbolo S, Jóźwik-Pruska J, Kałużna-Czaplińska J. The Role of Vitamins in Autism Spectrum Disorder: What Do We Know? J Mol Neurosci. 2019 Mar;67(3):373-387. doi: 10.1007/s12031-018-1237-5. Epub 2019 Jan 3. PMID: 30607900.

Authors

April Allen, RDN

Brittyn Coleman, MS, RDN/LD, CLT

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