Every cell in the body is busy producing energy, repairing itself, and defending against daily wear and tear. As part of these natural processes, small, unstable molecules called reactive oxygen species (ROS), often known as free radicals, are formed. In balance, they’re manageable, but if too many build up, they can overwhelm the body’s defences. This is called oxidative stress, and over time it can affect how cells work.
Oxidative stress is not always harmful. In small amounts, free radicals have useful roles, such as helping immune cells fight infection. The problem arises when production outpaces defence, something that can happen more easily in today’s world of poor sleep, processed food, pollution, and high environmental exposures. This is where antioxidants come in, they help restore balance, keeping cells resilient.Coenzyme Q10 (CoQ10) is one of these key antioxidants. It supports energy production inside cells and helps protect them from oxidative stress.
What is CoQ10?
CoQ10 is a fat-soluble compound found in almost every cell of the body. It switches between two forms called ubiquinone and ubiquinol, which allows it to both generate energy and protect against cellular damage.
Inside the cell’s mitochondria, often called the “powerhouses” of the cell, CoQ10 works in the electron transport chain, the process that produces adenosine triphosphate (ATP), our main source of energy. At the same time, it can neutralise free radicals and help recycle other antioxidants so they remain active for longer.CoQ10 plays a central role in energy production and is therefore most concentrated in organs that work hardest, such as the heart, liver, kidneys, and muscles.
Mechanisms of Oxidative Stress
Free radicals are produced in many ways, for example:
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Energy production in mitochondria: a small amount of leakage during this process creates free radicals.
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Immune defence: white blood cells generate them to fight off bacteria and viruses.
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Environmental exposures: smoking, air pollution, and UV light add to the load.
In excess, free radicals can:
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Damage fats in cell membranes (lipid peroxidation).
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Alter proteins, affecting how they function.
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Disrupt DNA, the cell’s instruction manual.
Antioxidants are the natural counterbalance to all of this. CoQ10 is especially effective because it’s located right where free radicals are most often produced, in the mitochondria.
How CoQ10 Functions as an Antioxidant
In its reduced form (ubiquinol), CoQ10 neutralises lipid peroxyl radicals, stopping a chain reaction that would otherwise damage surrounding fats in cell membranes. This helps keep mitochondria and cells stable.
CoQ10 also works with other antioxidants. For example, it can regenerate vitamin E once it has been used up fighting free radicals. This matters because vitamin E is one of the body’s main protectors of fatty membranes, but it becomes inactive after donating an electron. By restoring vitamin E to its active form, CoQ10 extends its protective lifespan and strengthens the antioxidant network.
CoQ10 in Tissues with High Energy Demand
CoQ10 is both an energy carrier and an antioxidant, which makes it especially important in parts of the body with high energy needs:
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Heart: The heart beats around 100,000 times each day and relies on a dense concentration of mitochondria to sustain this constant workload. CoQ10 plays a central role in fuelling energy production while also protecting heart cells from oxidative stress.
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Muscles: During exercise, oxygen demand in muscle cells rises sharply, which increases free radical production. CoQ10 supports the mitochondria that generate energy for muscle contraction and recovery, helping to keep oxidative stress under control.
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Brain: Although it represents only a small part of body weight, the brain uses a large share of the body’s oxygen, making its cells especially sensitive to free radical activity. CoQ10 helps protect neuronal mitochondria and supports the stability of brain cell membranes.
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Skin: As the body’s outer barrier, the skin is directly exposed to sunlight, pollution, and other environmental factors that increase free radical activity. CoQ10 helps defend skin cells at the surface and supports the resilience of their membranes against oxidative stress.
Getting CoQ10 from Diet and Within the Body
Small amounts of CoQ10 are found in food. Oily fish such as salmon and mackerel, organ meats like liver and kidney, and nuts including peanuts and pistachios are some of the best sources. Plant-based foods provide smaller amounts, so most of the CoQ10 the body uses comes from its own production.
Levels peak in early adulthood and naturally decline as we age. By the age of 80, CoQ10 levels in the heart muscle may be about half of those seen in early adulthood. Lower levels mean the mitochondria, the parts of cells that produce energy, do not work as efficiently, and the heart’s natural antioxidant defences are also reduced. This age-related decline happens because the body makes less CoQ10 and breaks it down more quickly, which can leave cells more vulnerable to oxidative stress over time.Some medications, such as statins, can also reduce CoQ10 by blocking part of this pathway.
CoQ10’s Dual Role in Energy and Antioxidant Defence
CoQ10 is a unique nutrient that helps our cells in two important ways. It’s essential for making energy and provides protection against oxidative stress. This is particularly valuable in tissues like the heart, muscles, brain, and skin, which demand a lot of energy and are exposed to higher levels of free radicals.
While the body makes most of its own CoQ10, levels gradually decline with age and can be affected by lifestyle and certain medications. For this reason, CoQ10 continues to be studied as both an energy-supporting compound and a key part of the body’s antioxidant defence system.*The advice in this article is for information only and should not replace medical care. As with any nutritional supplement please consult your qualified healthcare professional before use, especially if pregnant, breastfeeding, if you have a known medical condition or are taking medication. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle.
