All our life processes seem to be orchestrated according to a preprinted instruction manual—our cellular DNA. However, DNA is susceptible to damage, which can result in various diseases, including cancer, and contribute to aging. So how can we prevent, mitigate, or even repair DNA damage?
2 Main Causes of DNA Damage
Human DNA is approximately 2 meters long, structured like a long, twisted ladder coiled within a cell’s nucleus, approximately 10 micrometers in diameter. DNA carries the instructions necessary for human development, survival, and reproduction. Our cells read these instructions to produce various proteins essential for life processes. For example, DNA serves as a guide for cells to produce various hormones, including insulin.
“DNA damage is a constant occurrence in the body of a healthy individual,” Professor Qing-Bin Lu from the Department of Physics and Astronomy, Department of Chemistry, and Department of Biology at the University of Waterloo in Canada, said during an interview with The Epoch Times.
DNA is actually quite fragile. Even though it resides within the cell nucleus, it is constantly exposed to threats and susceptible to damage.
Exogenous Causes (External Environment)
Ultraviolet radiation, ionizing radiation, chemical toxins, air pollution, and tobacco smoke, among other factors, can cause DNA damage.
“When the DNA is damaged, the instructions can be corrupted, and the proteins that are made can be abnormal, or not made at all,” explained Dr. William Li, president and medical director of the Angiogenesis Foundation and bestselling author of “Eat to Beat Disease: The New Science of How Your Body Can Heal Itself,” during an interview with The Epoch Times.
“This DNA damage is the basis for mutations in our cells that can ultimately lead to cancers forming in our organs. This is why repeated sunburn, or chemical exposure, or cigarette smoking, for example, often leads to cancer.”
“Sudden exposure to a high dose of radiation over a short period of time results in significant genetic mutations and cell death in the body. This is why astronauts face a much higher risk of developing cancer compared to the general population. This increased risk may also be observed in the case of Madame Curie, who died from cancer due to her extensive exposure to radiation in her work,” added Mr. Lu.
Endogenous Causes (Within the Cell)
In addition to the damage from the external environment, DNA faces various threats from within the cells.
Human cells undergo metabolism, converting nutrients into energy and vital substances to sustain life. However, some byproducts, such as reactive oxygen species (ROS), are also generated during this process.
“Reactive oxygen species (ROS) are classified as free radicals, and they are not a single substance but rather a category of substances,” Mr. Lu explained.
These ROS are highly unstable and can cause DNA damage. It is estimated that each of our cells experiences tens of thousands of such damaging events daily. Oxidative damage from ROS accounts for a significant portion of all DNA damage.
“Think of DNA as a ball of yarn in which the fibers are perfectly twisted together,” explained Dr. Li. “Think of free radicals and ROS like metal pins that can snag, pull, and cut the yarn so the fibers are broken and untwisted.”
The damage to DNA from within the cells is significant. In fact, in many human tissues or animal models of carcinogenesis, the levels of oxidative DNA damage exceed that caused by exposure to exogenous carcinogenic compounds.
Innate DNA Repair Mechanisms in the Human Body
That being said, there is no need to be overly worried.
“There are repair mechanisms in our bodies, so generally, there are no issues,” Mr. Lu explained. “Within the cells, specific enzymes continuously monitor and assess the condition of DNA. If any damage is detected, they will recruit specific proteins to repair the DNA.”
“Our DNA is hardwired to defend and protect itself,” explained Dr. Li in his book “Eat to Beat Disease.” Enzymes in the cells act like scissors, trimming off the damaged sections of DNA and replacing them with the correct structure and sequence.
A recent study also discovered that when human cells encounter DNA damage induced by chemical substances, the cells will instruct an antioxidant enzyme to enter the nucleus and eliminate ROS, thereby preventing further DNA damage.
Why ROS Are Important for Health
It is worth noting that both Dr. Li and Mr. Lu emphasized a crucial point during their interviews—the ROS that can damage DNA are actually essential substances for human health.
Mr. Lu pointed out that the belief that ROS and free radicals are entirely harmful substances is a significant misconception.
ROS exhibit a dual nature. While they can cause damage, they are also essential for the human body and are crucial in maintaining cellular and physiological functions. For example, they aid in clearing cellular debris within the body.
He gave two examples of ROS.
Hydrogen peroxide (H2O2) is an ROS produced during cellular respiration, but it serves as a vital signaling molecule, playing a significant role in the body’s immune defense. Another ROS, nitric oxide (NO), is well known for its physiological functions in vasodilation and increasing blood flow. It also acts as a signaling molecule and contributes to the body’s innate immune defense in conjunction with hydrogen peroxide.
Additionally, our bodies can produce a variety of antioxidant enzymes, which help maintain a balance with ROS.
“Without any free radicals or ROS, you would not survive,” said Dr. Li. “The problem is when they are in excess.”
Foods That Help Protect DNA
As we age, the antioxidant capacity of cells may decline. In certain disease conditions, such as infections and inflammation, the increase in the production of ROS and other oxidants may surpass the antioxidant capacity, leading to a state known as oxidative stress.
This condition can be exacerbated by factors such as air pollution, exposure to chemicals in daily life, highly processed foods, high-fat diets, stress, tobacco smoke, and alcohol.
A diet rich in antioxidants can aid in neutralizing free radicals in the body and counteract the oxidative stress on DNA induced by ROS.
Many foods contain natural bioactive compounds. “The effect of these bioactives is to neutralize the free radicals, so they are no longer able to damage DNA and cells. This function of neutralizing free radicals is known as antioxidation,” explained Dr. Li. These compounds form a line of defense against oxidative damage.
In 2006, German researchers published a study in the Biotechnology Journal in which one group of participants consumed 700 milliliters of red berry juice rich in polyphenols daily. Meanwhile, another group served as the control and drank polyphenol-depleted juice. The laboratory results showed that consuming polyphenol-rich juice led to a reduction in oxidative DNA damage and an increase in antioxidant capacity within the body. In contrast, the control group did not exhibit such responses.
In a randomized crossover study, Norwegian researchers demonstrated the protective and reparative effects of consuming kiwifruit on human DNA. Compared to before consumption, daily kiwifruit intake for three consecutive weeks reduced oxidative damage in lymphocytes and enhanced DNA repair.
Italian scientists also confirmed that young smokers who consume 250 grams of steamed broccoli daily for 10 consecutive days experienced a 41 percent reduction in oxidative damage to cell DNA and a 23 percent increase in antioxidant capacity.
Vitamins A, C, and E
These vitamins are antioxidants that can eliminate free radicals within cells, preventing or reducing damage caused by oxidation. They are abundantly found in various fruits, vegetables, and dried fruits.
Red-colored fruits and vegetables like tomatoes, apricots, pink grapefruits, and watermelons are rich in the antioxidant lycopene.
Apples, grapes, citrus fruits, berries, onions, olive oil, and tea are rich in flavonoids, which exhibit antioxidant effects.
In his book, Dr. Li also highlights that berry juice, kiwifruit, carrots, broccoli, seafood, and lycopene-rich foods have been proven to impact DNA repair in clinical trials positively.
Should We Take Antioxidant Supplements?
When it comes to antioxidant effects, people often think of a category of products found in the market—that is, antioxidant supplements.
“Supplements are attempts to put together in a capsule or pill bioactive chemicals that have antioxidant effects. They can be helpful, but it is impossible to replicate enormous amounts of the bioactives present in fruits and vegetables,” said Dr. Li. He believes “eating whole foods is the best approach for protecting your DNA against oxidative stress and damage from free radicals.”
Mr. Lu is very cautious when it comes to antioxidant supplements. “Consuming more fruits to obtain antioxidant benefits is fine, but I personally recommend being extremely careful with antioxidant supplements. It’s best not to take them blindly, as they could potentially cause significant harm to the body.”
This is because supplements are often not equivalent to concentrated versions of foods. They may contain numerous synthetic nutrients, and their effects on the body may also vary from those of natural foods.
He pointed out that clinical trials have shown an increased risk of lung cancer with certain antioxidant supplements, such as beta carotene. Similar conclusions were also drawn from experiments conducted on mice and human cells. Additionally, antioxidant supplements may potentially increase the risk of skin cancer. “Based on the data I have seen and my own research experience, I firmly believe that the harm caused by blindly taking such health products far outweighs the benefits, meaning the disadvantages outweigh the advantages,” he emphasized.
Mr. Lu believes that maintaining a healthy and balanced lifestyle, including a proper diet, positive emotions, and regular exercise, may be more beneficial for DNA protection and repair than supplements.
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