Too much of a good thing: Antioxidants

4 min readMay 26, 2024


Berries as a representation of natural sources of antioxidants
Source: MedlinePlus

What are antioxidants?

“Antioxidants are molecules that neutralise free radicals, unstable molecules that can harm our cells and cause further serious health conditions.” — Arnarson, 2022

Can we take too many antioxidants?

Many people consume antioxidants mainly based on intuition and presumed benefits, such as their role in reducing exercise-induced oxidative stress. — Li, Fasipe and Laher, 2022

However, research shows that large amounts of antioxidants in the body may interfere with normal cell functions, including their defense mechanisms and normal signaling.

It’s also important to note that “different types of antioxidants may not be interchangeable. Each of the many antioxidants found in the body have different properties.” — Arnarson, 2023

What happens if we take too many antioxidants

Antioxidants intake is necessary for good health, but more is not always better! An adequate balance between free radicals and antioxidants is a an essential factor for maintaining a healthily functioning body.

High-intensity and frequent exercising generates large amounts of ‘reactive oxygen species’ (ROS) due to the consumption of large volumes of carbon dioxide (O2), especially in the case of athletes, who are training more than the general population. This results in some athletes consuming and supplementing with antioxidants hoping that this will counteract the damaging effects of ROS. However, there is currently no evidence to prove the benefits of antioxidant supplementation in such cases.

On the contrary, excessive intake of antioxidants prevents some essential functions of free radicals that are needed for cell signaling, which may further affect an athlete’s performance levels, ability to adapt to training routines and overall health. More specifically, this could interfere with the natural outcomes of exercising, such as:

  • Mitochondrial biogenesis: The growth and division of pre-existing mitochondria. Mitochondria is also known as the ‘powerhouses of the cell’, producing the energy necessary for the cell’s survival and functioning by breaking down glucose into energy. — Rogers, 2024; Sandhir and Garg, 2021
  • Skeletal and cardiac muscle hypertrophy: The excessive development of an organ or part, resulting from the increase in the size of fibers without an increase in their number. — Paul and Rosenthal, 2002; Merriam Webster, 2024
  • Improved insulin sensitivity: Insulin is an essential hormone that controls blood sugar levels. Improved insulin sensitivity means the body is well responsive to insulin, which is beneficial to overall health. — Gunnars, 2022

Despite this, there remains the flawed perception that antioxidants tackle oxidative stress and benefit training performance. Actually, it’s more likely that the negative effects of high dosage of antioxidants exceed the presumed benefits.

Antioxidants classified based on bioactivity, solubility and size
Different classes of antioxidants. Source: Ayoka et al., 2022

Excessive intake of isolated antioxidants (opposed to a wholistic, moderate intake) can have toxic effects and could trigger, rather than prevent, oxidative damage — a phenomenon called ‘the antioxidant paradox’. This is because excessive antioxidant levels lead to reductive stress, which is the opposite of oxidative stress. Chronic reductive stress can induce oxidative stress, which in turn stimulates greater reductive stress formation, therefore creating a vicious cycle that would need to be broken in order to restore optimal health and performance abilities as an athlete.

How to regain balance after supplementation with high doses of antioxidants

First, to restore the natural balance in our bodies, we shall refrain from taking supplements — of all kind — for a prolonged period of time (unless otherwise specified by a medical professional). Alongside this, we should also ensure a healthy, active lifestyle and a nourishing diet.

This means we need to maintain a balanced diet, suitable to our lifestyle, season, level of physical activity and age, while avoiding products our bodies cannot tolerate well, to avoid adding in additional stress factors.

Last but not least, we should always eat our fruits and veggies! They provide us with the optimal amount of antioxidants from natural, bioavailable sources, that our bodies find easier to metabolise, alongside all other benefits of these foods, such as fiber and protein! To make sure we restore our bodies’ balance, we need to eat a variety of these foods, since there’s a variety of antioxidants with different functions in our bodies, as mentioned above. We listed the best antioxidant-rich foods that can easily be integrated in our diets in the section below!

Natural sources of antioxidants

These include foods rich in flavonoids, vitamin C and vitamin E.

  • Flavonoids: berries, red cabbage, onions, kale, parsley, green tea, red wine, dark chocolate
  • Vitamin C: strawberries, blackcurrants, citrus fruit, peppers, kiwis, broccoli, tomatoes, cabbage, peppers
  • Vitamin E: sunflower seeds, walnuts, almonds, fatty fish such as mackerel and salmon, olive oil, shrimp, avocados

List of references

Arnarson, A. (2023) Antioxidants Explained in Simple Terms [online] available from

Ayoka, T. O., Ezema, B. O., Eze, C. N. and Nnadi, C. O. (2022) Antioxidants for the Prevention and Treatment of Non-communicable Diseases. DOI: 10.14218/JERP.2022.00028

Gunnars, K. (2022) Insulin and Insulin Resistance: The Ultimate Guide [online] available from

Li, S., Fasipe, B. and Laher, I. (2022) Potential harms of supplementation with high doses of antioxidants in athletes. DOI: 10.1016/j.jesf.2022.06.001

Merriam Webster (2024) hypertrophy [online] available from,hy·%E2%80%8Bper·%E2%80%8Btro·%E2%80%8Bphy%20hī%2D,fibers)%20without%20multiplication%20of%20parts

Paul, A. C. and Rosenthal, N. (2002) Different models of hypertrophy in skeletal muscle fibres. DOI: 10.1083/jcb.200105147

Rogers, K. (2024) mitochondrion — biology [online] available from“powerhouses%20of,fuel%20various%20other%20cellular%20processes.

Sandhir, R. and Garg, P. (2021) Increasing resveratrol bioavailability: A therapeutic challenge focusing on the mitochondria. DOI:




Driven by our passion for sports, we have made it our goal to contribute to the development of the sports world. // 私たちはスポーツへの情熱を胸に、スポーツ界の発展に貢献することを目標としています。