Free Radicals and Oxidative Stress

Every atom and molecule has electrons circling around it. These electrons like to fly around in pairs, which keeps the atoms and molecules nice and stable and balanced. But once in a while, one of those electrons breaks free—and that’s when all the trouble starts. Once one of the paired electrons breaks off, the molecule or atom where it used to reside is now running around with an unpaired single electron. The presence of that “unpaired” electron turns our formerly stable molecule into what is known as a free radical—the raging bull of molecules. The free radical starts “hitting” on every molecule it encounters, looking for another electron to steal away from a normal, stable molecule that still has all its electrons neatly paired up.

Free radicals are dangerous molecules created from oxygen (sometimes called oxygen free radicals or reactive oxygen species). These rogue molecules attack your cells and damage your DNA and slowly “wear you down,” aging you from within. This insidious damage is called oxidation and is similar to the rusting that happens when you leave metal out in the rain or the browning that happens when you leave apple slices out in the sun.

The irony, of course, is that when it does finally steal an electron away from a stable molecule, that molecule becomes unstable itself and turns into a free radical (because it’s now left with an unpaired electron). And the process begins again. Every time these free radicals “hit” on your cells looking for a mate for their unpaired electron, they damage the cells. This cumulative oxidative damage is a huge part of aging. If the DNA is damaged when the cell divides to make new cells, the copies will be wrong and whatever function that cell performs thereafter will not be done correctly.

If “aging” is another name for “breakdown,” then you can see immediately why free radicals age us. Cells break down, organ systems don’t function as well, DNA becomes damaged, DNA replication doesn’t happen efficiently, and DNA can become mutated. When this kind of damage accumulates in the body it contributes to all sorts of disorders typical of aging.

For example, when it accumulates in the heart or vascular system, you have heart disease. When it accumulates in the skin, you have aging skin. There’s not a disease of aging in which free radical damage is not an important component. That’s why fighting free radical damage is so important.

The role of free radicals in aging has been recognized at least since the 1950s, when an innovative scientist named Denham Harman, M.D., Ph.D., proposed the free radical theory of aging. Harman believed that as go the cells, so goes the body; if our cells age, our whole body ages. Harman saw aging as the cellular accumulation of free radical damage over time—that our bodies are essentially “rusting from within.”

Years later, the free radical theory of aging was expanded to include not just aging, but degenerative diseases in general. We now know that oxidative damage plays a major role in every degenerative disease of aging, from Alzheimer’s and cancer to heart disease and diabetes and even immune dysfunction.

There are several sources of free radicals, including the environment. Tobacco smoke, air pollution, pesticides, herbicides, contaminants in our water; all of these form free radicals—which we then take into our body by breathing, drinking, and eating—that contribute to the aging process and the diseases that kill us. This is what we mean when we talk of a “toxic environment”. People who are constantly assaulted by these environmental free radicals—and who don’t have good defenses against them—tend to age badly. The free radicals come into our body and attack our cells. They destroy genetic material, damage and mutate DNA, burden the immune system, and virtually destroy a cell’s identity. The damage is enormous, and it’s a huge part of what ages us.

Some of the obvious sources of free radicals—tobacco smoke, pesticides, and certain chemicals—are also sources of cancer-causing chemicals called carcinogens. The combination is lethal to anyone wanting to live in optimal health for nine or more decades. Smoking, for example, creates free radicals that damage the lungs and just for good measure, exposes us to carcinogenic chemicals. Tobacco smoke is literally a turbo-charged free radical factory on steroids. Then there are the pesticides sprayed on crops. “Pesticides kill the pest by creating free radicals,” says Hari Sharma, M.D., a fellow of the Royal College of Physicians and Surgeons and a consultant to the National Institutes of Health. “If you consume them, you will be damaged by those free radicals, also.”

At least fifty-three carcinogenic (cancer-causing) pesticides are applied in large amounts to the major food crops, according to a study by the U.S. Food and Drug Administration. In 2005, for example, 73 percent of fresh vegetables and fruits contained pesticide residues, as did 61 percent of processed fruits and vegetables, 22 percent of soybeans, 75 percent of wheat, a whopping 99 percent of milk and cream, and 16 percent of bottled water.

It gets worse. The Centers for Disease Control and Prevention tested for 116 pesticides and other artificial chemicals in the blood and urine of 2,500 volunteers and found detectable levels of 89 chemicals, including pesticides, phthalates, herbicides, pest repellents, and disinfectants. “The effects of these chemicals may be difficult to separate from normally mildly debilitating aspects of the aging process,” says professor Harvey Blatt of the Institute of Earth Sciences at Hebrew University of Jerusalem.

This is the primary reason for recommending organic foods as part of an anti-aging lifestyle. Although studies have been mixed about whether the nutritional content of organic food is any greater than that of conventionally grown food, the primary reason for eating organic food is to avoid the intake of the chemicals used in non-organic farming.

The environment isn’t the only source of these toxic free radicals. Our own bodies are a virtual free radical factory. Now why in the world would you produce free radicals in your body, you might ask, especially because these are such dangerous and health-robbing compounds? Good question, and the answer is simple: All free radicals aren’t bad. Our immune system, for example, produces free radicals to help protect us from harmful microorganisms and fight infections. The very process of creating energy—respiratory metabolism, or in simpler terms, breathing —creates free radicals. Free radicals can help activate enzymes and produce hormones. The problem arises when the amount of free radicals in our body is excessive and out of control. Then the damage significantly outweighs the benefits.

Although free radicals can search for that extra electron anywhere, they cause the most damage when they are derived from oxygen, the stuff you breathe and without which you couldn’t live for more than a few moments. But oxygen has a dark side. Oxygen free radicals are actually one of the most damaging kinds on the planet. When oxygen molecules are the ones that give up their electrons, we’re in big trouble.

Free radicals derived from oxygen are known collectively as reactive oxygen species, and they are a virtual aging factory. Oxygen-derived radicals are a normal part of aerobic metabolism, so they’re constantly being formed. In fact, anywhere there’s oxygen, there are oxygen free radicals. Doing some aerobic exercise? You’re making oxygen free radicals! Just breathing? Oxygen free radicals! White blood cells are especially talented at producing oxygen free radicals, which they then use as a defense against invading microbes.

But all those toxins from the environment that we spoke about earlier also have oxidizing effects on cells and produce tons of oxygen free radicals. So does radiation, which actually produces the most damage in tissues that have a heavy concentration of oxygen (we call these heavily oxidized tissues).

Another way free radicals age us is through their effect on DNA. Your DNA is kind of like your own individual genetic instruction manual. It’s found in every cell and it’s like a set of master blueprints that tell every other cell what to do. When free radicals attack the DNA in your cells, they screw up their ability to replicate properly and pass on their instructions. This kind of DNA damage eventually shortens your DNA strands and triggers a process called apoptosis, or “programmed cell death.”

It’s as if you were passing on a repair manual that constantly got dropped in the dirt, burned at the edges, or dropped in the water and finally became so worn that anyone trying to use it couldn’t read the words anymore and had to guess what was written on the page. A mechanic relying on a manual like that couldn’t be counted on to do a good job with your car, and DNA that’s been damaged like that doesn’t do a good job of repairing and rebuilding your cells, tissues, and organs. The result? What we know as aging!

One of the best-known toxic effects of oxygen free radicals is the damage to cellular membranes. Nothing will age you faster than an assault on your cell membranes, even though it takes place under the radar and even though you can’t see it. Why? Because the membranes are critical to cell health—they’re what hold the cell together. Cell membranes have to be flexible enough to allow information to pass in and out, but stiff enough so that they don’t collapse. They’re delicate structures. (One of the reasons trans fats are so harmful is that they damage the cell membrane.)

Cell membranes are made up largely of fats (lipids) called phospholipids, and the oxidative damage done to cell membranes is called lipid peroxidation. The fats that are most vulnerable to this kind of oxidative damage are the very fats we’ve been told to eat more of— unsaturated fats like vegetable oil. Those fats are much more susceptible to oxidative damage than the more stable (and stiffer) saturated fats. A paradox, but it’s completely true. Does that mean we shouldn’t eat unsaturated fats? No. But it does mean they need special protection in the form of antioxidants if we’re going to get their full benefit.

The vulnerability of unstable fats to oxidative damage is actually the reason why health practitioners always recommend a little vitamin E with your fish oil. Fish oil, one of the healthiest, most anti-aging compounds on the planet, is nonetheless made up of delicate fatty acids extremely vulnerable to damage from both heat and oxygen (that’s why you can’t cook with either fish oil or flaxseed oil). Vitamin E is a powerful antioxidant and will protect the delicate structures of the omega-3 fatty acids in fish (and flax).

Lipid peroxidation—the damage to cell membranes caused by oxygen free radicals—can have a number of effects, none of them good. It can make the membranes stiffer. It can decrease the activity of enzymes that are bound in the membranes. It can alter the activity of membrane receptors. Ultimately, on the cellular level, lipid peroxidation ages you from the inside out.

One of the most God-awful missteps made by conventional medicine and conventional public health policy has been to focus on cholesterol lowering as an anti-aging strategy when in fact the big risk factors for disease are oxidative damage and inflammation. Cholesterol itself doesn’t do any damage in the body at all—until it’s oxidized. When cholesterol just sits there minding its own business, it is perfectly harmless. Only when it gets attacked by oxygen free radicals does it become a problem. If we could prevent the oxidation of cholesterol by fighting off free radical damage, as well as preventing or reversing the inflammation that nearly always accompanies this oxidative damage, we’d be sitting pretty. Oxidized cholesterol is indeed a health risk, but blaming poor cholesterol is like blaming the St. Bernard for the avalanche.

By now it should be pretty apparent that there’s no aging without free radical damage, and there’s no way to fight the effects of aging without a strong army to fight off that damage. If your body didn’t have any built-in defenses against the constant assault of free radicals, you probably wouldn’t be here reading this book. In fact, you’d be quite dead. Fortunately, nature hardwired into our DNA the ability to make chemicals that help protect the cells against oxidative damage. These chemicals are called antioxidants.

An antioxidant works by fighting oxidation. It donates one of its own electrons to the rogue molecule, essentially rendering it impotent and unable to do any damage. You’ve probably used the power of antioxidants yourself without realizing it. When a cook slices up some apples, she’ll often squeeze some lemon juice over them. Left alone without that protection, the apple slices will turn brown—that’s oxidation (or oxidative damage) in action. But the lemon juice contains powerful antioxidants, including vitamin C, and thus apple slices “protected” with this antioxidant will survive in the air a lot longer without changing color.

Your body has some powerful antioxidants of its own. At the top of the list is one called coenzyme Q10, which is found in every cell. Another is called superoxide dismutase (SOD), an enzyme that repairs cells and reduces damage done by one of the most common (and damaging) oxygen free radicals in the body—superoxide. SOD works its magic by breaking down the harmful superoxide into two harmless components—oxygen and hydrogen peroxide. Rounding out this native superstar trio is glutathione, arguably the most important antioxidant in the body.

“These built-in antioxidants keep us alive through the reproductive age,” explains Rothenberg. But there’s one big problem. They can’t keep up with the workload. Our internal antioxidants become less effective as we age, especially when we live in an environment that assaults us with free radicals on a daily basis. 11 “After 30, these built-in antioxidants cannot keep up with the cellular damage that has been produced by free radicals.

What can you do about it? Eat plenty of vegetables and fruits, all high in antioxidants, and consider adding antioxidant supplements . Plants have their own built-in protection against the oxidative damage of the sun, and these built-in protectors function as cell protectors in our bodies. The very pigments that make blueberries blue and raspberries red protect those berries from oxidative damage, and they do the same for you once inside your body. It’s a safe bet that any of the foods from the leafy green vegetable family, the brassica family (Brussels sprouts, cabbage, broccoli), any beans and legumes, or any brightly colored vegetables and fruits are going to contain a whopping number of antioxidants that will help your body fight off the damaging, aging effects of free radical attacks. This is probably one of the many reasons for the greater health and longevity of people who regularly consume tons of fruits and vegetables. If you can pluck it or gather it—if it’s a food you could eat straight from the ground or right off a tree or a bush—it’s probably good for you. These are the foods that make up a large part of the diet of virtually every one of the longest-lived and healthiest populations on the planet.

The most famous of the powerhouse antioxidants are vitamin C and vitamin E, but that’s only the beginning of the list. Vitamin A is an antioxidant. Minerals like zinc and selenium are powerful antioxidants, as are dozens, perhaps hundreds, of plant compounds known as phytochemicals. Quercetin, for example, a member of the flavonoid family, is found in apples and onions and has tremendous antioxidant activity. So does curcumin, a phytochemical found in turmeric, the spice that makes Indian food yellow. Spices in general are a tremendous source of antioxidants. And nutrients rarely found in any appreciable amount in food, such as alpha-lipoic acid, are also tremendous weapons in the battle against oxidative damage.

Popping a couple of supplements and optimizing your antioxidant stores—propping up your internal defenses against the aging effects of free radical damage—is a big part of any strategy for living longer. It’s no accident that every anti-aging clinic in the world routinely recommends high levels of antioxidant supplementation in its programs. You can pretty much cover all the antioxidant bases by simply following one of the smartest overall pieces of nutritional advice for anti-aging I ever heard, all the more elegant because of its utter simplicity: Shop so your grocery basket looks colorful. You will automatically be eating a ton of high-antioxidant foods that will help protect you from a virtual encyclopedia of syndromes and diseases associated with aging.

adapted from Jonny Bowden from The Most Effective Ways to Live Longer, pp 20-44