Antioxidants
What are Antioxidants?
Antioxidants are naturally occurring, molecules that help to fight or neutralize free radicals produced within the body and are sometimes called “free-radical scavengers”. [1]
Children with autism are known to have an imbalance in free radical production and antioxidants, called oxidative stress. Eating a diet high in antioxidant-rich fruits and vegetables can help neutralize this free radical imbalance.
There are hundreds of different antioxidants that act in a similar way, but each has its own unique benefit to health.
Antioxidants are produced both naturally by the body and are also found in the foods we eat.
What are Free Radicals?
Free radicals are waste products produced by the body as it breaks down food and reacts to the environment. Free radicals are constantly formed within our bodies as a result of everyday metabolism and chemical reactions.
It is important to note that not all free radicals are bad. They also play an important role in the body. For example, the immune system uses free radicals to fight off infections.
When there are too many free radicals and not enough antioxidants, oxidative stress can occur.
What is Oxidative Stress?
Oxidative stress occurs when there is an imbalance between free radicals and antioxidants.
Oxidative stress can damage cells, DNA, tissues, and organs very quickly. [1]
Oxidative stress has been linked to rapid aging, heart disease, cancer, Alzheimer’s, diabetes, liver disease, kidney disease, Parkinson's Disease, Autism, and so much more. [1]
Common Antioxidants
Most fruits and vegetables, especially berries, oranges, and bell peppers
Beta-carotene
Lycopene
Pink and red fruits and vegetables, including tomatoes and watermelon
Lutein
Selenium
Brazil nuts, rice, wheat, and other whole grains, as well as nuts, eggs, cheese, and legumes
Other Antioxidants
Resveratrol
Catechins
Anthocyanins
Alpha Lipoic Acid
Zeaxanthin
Astaxanthin
Flavonoids
Rutin
Hesperidin
Pycnogenol
Bilberry
Source: Autism Dietitian Library
Food Sources of Antioxidants
Plant-based foods are a rich source of antioxidants. Studies have shown that individuals that eat a diet rich in fruits and vegetables have a lower risk of disease. It is antioxidants that give plants this amazing attribute. [2]
Ever heard the phrase “Eat the rainbow’? Antioxidants are what give foods their colors. Foods that are bright and have vibrant colors often have the greatest amount of antioxidants.
Cooking methods can increase or decrease antioxidant availability in foods. For example:
Lycopene, an antioxidant in tomatoes that gives them their bright red color, becomes easier for our bodies to absorb when tomatoes are heated.
Vegetables rich in Vitamin C, like broccoli or zucchini, will lose a significant amount of antioxidant Vitamin C when boiled and the water is poured off. [3]
In general, eating foods raw, steamed, low heat sautéed, or microwaved can help preserve the greatest amount of antioxidant content. [3]
Keep in mind that the goal should be to eat a diet high in antioxidant-rich colorful fruits and vegetables both cooked and raw to get a balance of antioxidants.
Fruits:
Goji Berries
Pomegranates
Apples
Vegetables
Grains & Legumes:
Nuts, Seeds & Their Oils:
Walnuts
Pecans
Other:
Green & Black Teas
Coffee
Dark Chocolate
Most Herbs and Spices
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.
Although it is thought that there are hundreds, even thousands of nutrients and chemicals that can act as antioxidants, the RDA is only created for nutrients recognized as “antioxidants” by the Food and Nutrition Board. These include: Vitamin A, Vitamin C, Vitamin E, and Selenium. [4] Visit these notes to learn more about their RDA.
Deficiency
Deficiency-related signs of antioxidants will depend greatly on the specific antioxidant in question.
Since the role of antioxidants as a whole is to fight free radical production, there are several signs that could point to inadequate intake of antioxidants through food intake. This deficiency is displayed as the results of oxidative stress and includes [5]:
Fatigue
Memory concerns
Difficulty concentrating
Headaches
Sensitivity to sound
Decreased vision
Susceptibility to infection
Joint pain
Insomnia
Individuals That May be at Increased Risk for Inadequate Intake of Antioxidant-Rich Foods Include:
Those with poor intake of fruits and vegetables
Those with high sugar intake
Those with a diet high in processed or fast foods
Those with food allergies and/or sensitivities
Certain dietary, lifestyle, and environmental choices can increase harmful free radical production in the body which results in a need for more antioxidant-rich foods. These include:
Excessive alcohol intake
Cigarette smoking
Air pollution
High blood sugar levels
Toxins
Bacterial, fungal, or viral infections
Excessive or prolonged exercise
High sugar and processed food intake
Prolonged UV exposure from the sun
High intake of omega 6 fatty acids as compared to omega 3 fatty acids
Toxicity
The Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.
There is no specific Upper Limit for antioxidants as a whole. However, high intakes of some supplemental antioxidants (Vitamin E and Beta Carotene) have been linked to adverse side effects. [9]
The UL is only created for nutrients recognized as “antioxidants” by the Food and Nutrition Board. These include Vitamin A, Vitamin C, Vitamin E, and Selenium. Visit these notes to learn more about their toxicity/UL.
Supplements
The best way to get antioxidants is through a nutrient-dense diet rich in a variety of colorful fruits and vegetables.
There are thousands of antioxidant supplement combinations on the market. The ones listed below are a more comprehensive blend of various antioxidants.
Examples:
Capsules:
Powder:
Each antioxidant has its own unique benefit. Research which antioxidant may meet your specific need before considering a supplement.
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.
Antioxidants & Autism in the Research
Antioxidants and Oxidative Stress
Individuals with autism have been shown to have increased levels of oxidative stress and a lower capacity for antioxidants. [6]
Some important antioxidant enzymes required to fight free radicals are altered in autism suggesting a decreased ability to neutralize free radical production. [6]
A review of several studies concluded that the function of certain antioxidant enzymes such as glutathione were altered in individuals with autism. [6]
It is suggested that the combination of increased free radical production and decreased ability to neutralize free radicals, in individuals with autism, may contribute to both the development and symptoms associated with autism. [6]
One study suggests that an early evaluation and treatment of antioxidant status could improve ASD outlook by decreasing oxidative stress in the brain which may, in turn, prevent additional brain damage. [10]
Antioxidants and Behavioral Changes
Children with autism are known to have an imbalance in the number of free radicals the body produces and the bodi’s ability to neutralize those free radicals with antioxidants. [7]
This imbalance can lead to oxidative stress and oxidative stress has been linked to the development of neurocognitive disorders, such as ASD. [7]
In this study, children with ASD were given high antioxidant dark chocolate over a 4 week testing period. They were evaluated on behaviors before and after the testing period. [7]
The study found that there may be a potential therapeutic benefit to antioxidants and the improvement of social communication and self-regulation behaviors in children with ASD. [7]
Several other studies found that antioxidant supplementation was linked to decreased autistic behaviors and/or the severity of those behaviors. [6]
More research needs to be done.
Antioxidant NAC, Irritability & Repetitive Behaviors
The antioxidant, N-Acetylcysteine or NAC, was supplemented to children with autism during a 12-week trial.
According to the Aberrant Behavior Checklist, NAC decreased the irritability score from 13.1 to 7.2. [8]
Additionally, children taking NAC showed a decrease in repetitive and stereotyped behaviors. [8]
*The NAC used was a pharmaceutical grade.
More research needs to be done to confirm these results.
Read more about NAC in the NAC note
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[1] Neha K, Haider MR, Pathak A, Yar MS. Medicinal prospects of antioxidants: A review. Eur J Med Chem. 2019;178:687-704. doi:10.1016/j.ejmech.2019.06.010
[2] Amarowicz R, Pegg RB. Natural antioxidants of plant origin. Adv Food Nutr Res. 2019;90:1-81. doi:10.1016/bs.afnr.2019.02.011
[3] Jiménez-Monreal et al. Influence of Cooking Methods on Antioxidant Activity of Vegetables. Journal of Food Science, 2009; 74 (3): H97 DOI: 10.1111/j.1750-3841.2009.01091.x
[4] Nutrient Recommendations : Dietary Reference Intakes (DRI). NIH Office of Dietary Supplements. https://ods.od.nih.gov/HealthInformation/Dietary_Reference_Intakes.aspx. Accessed February 23, 2021.
[5] Wu JR, Jia Rong Wu Search for more papers by this author, Song EK, et al. Abstract 12351: Dietary Antioxidant Deficiency is Associated With Increased Inflammatory Markers and Poorer Health-related Quality of Life in Patients With Heart Failure. Circulation. https://www.ahajournals.org/doi/10.1161/circ.136.suppl_1.12351. Published June 8, 2018. Accessed February 23, 2021.
[6] Manivasagam T, Arunadevi S, Essa MM, et al. Role of Oxidative Stress and Antioxidants in Autism. Adv Neurobiol. 2020;24:193-206. doi:10.1007/978-3-030-30402-7_7
[7] Sadek A, Berk LS, Mainess K, Daher NS. Antioxidants and Autism: Teachers' Perceptions of Behavioral Changes. Adv Mind Body Med. 2018;32(3):12-17.
[8] News Center. Antioxidant shows promise as treatment for certain features of autism, study finds. https://med.stanford.edu/news/all-news/2012/05/antioxidant-shows-promise-as-treatment-for-certain-features-of-autism-study-finds.html.
[9] Antioxidants: In Depth. National Center for Complementary and Integrative Health.https://www.nccih.nih.gov/health/antioxidants-in-depth.
[10] Hu T, Dong Y, He C, Zhao M, He Q. The Gut Microbiota and Oxidative Stress in Autism Spectrum Disorders (ASD). Oxidative Medicine and Cellular Longevity. https://www.hindawi.com/journals/omcl/2020/8396708/. Published October 1, 2020.
Authors
Brittyn Coleman, MS, RDN/LD, CLT
Sinead Adedipe, MS
