FREE RADICALS AND SKIN AGING: WHAT THEY ARE, HOW THEY WORK, AND HOW TO PREVENT THEIR DAMAGE
For years, free radicals were blamed for aging, but today we know that cellular damage goes far beyond oxidative stress. Discover how it affects your skin and what to do to protect it.
For decades, free radicals were considered the main culprits of aging. The well-known free radical theory of aging, formulated in the 1950s by Denham Harman, proposed that the progressive deterioration of the body was due to accumulated oxidative damage caused by highly reactive molecules known as reactive oxygen species (ROS). However, today this theory is being replaced by a broader approach: the damage theory, which recognizes multiple sources of cellular deterioration beyond oxidative stress.
WHAT ARE FREE RADICALS AND HOW DO THEY WORK?
Free radicals are molecules or atoms with one or more unpaired electrons in their outer orbit. This unstable state makes them highly reactive, as electrons tend to pair to achieve stability. Due to this instability, free radicals desperately seek to “steal” electrons from nearby molecules, triggering a chain of chemical reactions. By interacting with essential structures in the body such as proteins, lipids, and DNA, they can cause both structural and functional alterations. This can disrupt proper cellular function and contribute to cellular aging.
Free radicals are naturally produced as part of our body's normal metabolic processes, such as cellular respiration, where oxygen is used to generate energy. During this process, a small fraction of oxygen is reduced to free radicals. Although the body has defense mechanisms, like antioxidants, to counteract the effects of free radicals, various external factors can increase their production, leading to an imbalance the body cannot efficiently manage.
Free radicals are not only a natural byproduct of metabolism; they are also amplified by external factors. Some of these include:
EXCESSIVE SUN EXPOSURE (UV RAYS): Ultraviolet (UV) rays are one of the main sources of free radicals. Prolonged sun exposure leads to an overproduction of free radicals that damage the DNA of skin cells, triggering what is known as photoaging. This damage contributes to the development of wrinkles, spots, and loss of elasticity.
AIR POLLUTION: Pollutants in the air, such as nitrogen dioxide and ozone, also induce free radical formation. These toxic agents, when they come into contact with the skin, can cause cellular damage and accelerate the aging process.
TOBACCO SMOKE: Cigarette smoke is a rich source of free radicals that can penetrate the skin, affecting collagen and elastin fibers. This not only impacts overall health but also accelerates skin aging, contributing to premature wrinkles and a dull skin tone.
DIET HIGH IN SATURATED FATS, FRIED FOODS, AND ALCOHOL: The consumption of processed, fried, or high-fat foods promotes the formation of free radicals in the body. Additionally, alcohol can damage cells and reduce the effectiveness of antioxidants that normally neutralize these radicals. This can also contribute to inflammation and premature skin aging.
When the number of free radicals generated exceeds the body’s ability to neutralize them, a phenomenon known as oxidative stress occurs. This imbalance between the production of free radicals and the body’s antioxidant capacity leads to cumulative cellular damage.
Oxidative stress is one of the main causes of photoaging an accelerated form of skin aging caused by sun exposure. This damage is also associated with the appearance of dark spots (hyperpigmentation), wrinkles, and loss of skin firmness and elasticity, as free radicals attack key structures that keep the skin youthful, such as collagen and elastin.
OXIDATIVE STRESS: IMPACT ON THE SKIN
Oxidative stress occurs when there is an imbalance between free radicals and the body’s ability to neutralize them, especially through antioxidants. On the skin, this imbalance causes a series of adverse effects that negatively impact the structure and function of the dermis, accelerating the skin aging process.
Some of the main manifestations of oxidative stress on the skin include:
DEHYDRATION: Oxidative stress directly affects the skin barrier function, which acts as a natural filter to prevent excessive water loss. Free radicals attack the cells of this barrier, especially keratinocytes, leading to greater transepidermal water loss. This results in drier, rougher skin that is less capable of maintaining hydration, contributing to cutaneous dehydration.
UNEVEN SKIN TONE: Damage caused by free radicals also affects melanin production the pigment responsible for skin color. Oxidative stress can alter its distribution, causing dark spots and uneven skin tone. This occurs because free radicals interfere with melanocyte activity, the cells responsible for producing melanin. As a result, dark spots may appear, particularly in sun-exposed areas.
DULLNESS: The skin’s cellular renewal process is compromised by oxidative stress. Free radicals interfere with the cellular replication of keratinocytes and reduce the skin's ability to shed dead cells. This slows down cell renewal, creating a dull and tired appearance. The skin loses its natural radiance and becomes more prone to dead cell buildup, contributing to premature aging.
LOSS OF ELASTICITY: Collagen and elastin fibers, essential for maintaining skin firmness and elasticity, are especially vulnerable to damage caused by free radicals. As oxidative stress deteriorates these structural proteins, the skin loses its ability to retain its shape and elasticity, leading to wrinkles and sagging. This damage is particularly significant since collagen and elastin are responsible for the skin’s strength and flexibility, which are severely compromised over time.
DAMAGE TO KEY CELLS (FIBROBLASTS AND KERATINOCYTES): Fibroblasts, which produce collagen and elastin, and keratinocytes, which form the skin barrier, are deeply affected by oxidative stress. Free radicals alter their function and regenerative capacity, accelerating skin aging. Damaged fibroblasts fail to produce sufficient structural proteins, while impaired keratinocytes compromise the skin's protective barrier, reducing its effectiveness and increasing vulnerability to external aggressors.
ACCUMULATED DAMAGE
Over time, this accumulated cellular damage not only affects the external appearance of the skin but also accelerates the natural aging process, which already involves a gradual decline in the body’s antioxidant capacity. In other words, as the skin ages, its ability to defend itself against damage caused by free radicals decreases, increasing its susceptibility to oxidative stress and accelerating the skin aging process.
THE ROLE OF ANTIOXIDANTS
Antioxidants are molecules capable of donating an electron without becoming unstable, neutralizing free radicals and limiting the damage they cause. The body produces antioxidants naturally, but their effectiveness decreases with age, so it is advisable to supplement them through diet and topical care.
KEY ANTIOXIDANTS:
VITAMIN C: A powerful direct antioxidant, promotes radiance and reduces dark spots.
VITAMIN E: Protects the skin from UV damage.
NIACINAMIDE (VITAMIN B3): Soothes the skin and combats hyperpigmentation.
MELATONIN: Acts as an indirect antioxidant, repairing already existing damage.
The use of antioxidant-rich serums is an effective tool to combat oxidative damage. The use of sunscreens containing antioxidants is also recommended to maximize protection against sun damage.
BEYOND OXIDATIVE STRESS: THE DAMAGE THEORY
Although oxidative stress was long assumed to be the main driver of aging, numerous recent studies have begun to challenge this idea. Some research has shown that increasing antioxidant levels doesn’t always extend an organism’s lifespan and in some cases, it may even shorten it.
Additionally, aging occurs even under anaerobic conditions, where ROS are minimal. In such scenarios, aging continues due to other forms of cellular damage, leading scientists to look beyond free radicals.
Today, the dominant theory in the field of aging is the damage theory, which proposes that aging results from the inevitable accumulation of multiple types of cellular damage, including:
Errors in genetic transcription and translation
Damage to proteins and metabolites
Failures in intracellular transport
Imbalances in molecular factor levels
This broader and more complex approach seeks to understand why the body's repair and defense mechanisms fail over time, and why a permanent balance between damage and repair cannot be achieved.
PREVENTION AND SELF-CARE
While we cannot completely avoid the production of free radicals, we can moderate their impact through simple but effective strategies:
Maintain a diet rich in antioxidants (citrus fruits, leafy greens, legumes, oily fish).
Avoid smoking and reduce alcohol consumption.
Protect the skin from the sun with appropriate sunscreens.
Incorporate topical antioxidants into your daily skincare routine.
Get good sleep, stay hydrated, and manage stress.
Free radicals remain relevant, but they are no longer seen as the sole culprits of aging. Today we understand that aging results from a complex accumulation of cellular damage, of which oxidative damage is just one part. Nevertheless, preventing that damage remains crucial, especially to maintain youthful, firm, and healthy skin for longer.
Thus, a healthy lifestyle, a balanced diet, and the use of appropriate antioxidant products remain our best tools against the passage of time. Because while aging cannot be stopped, we can influence how it manifests.