by Larissa Long
Every day, on a constant basis, we’re barraged by free radicals. These unstable molecules alter or damage our cells, leaving us vulnerable to some of the most common and dreaded health problems of our time, including cataracts, macular degeneration, heart disease, diabetes, Alzheimer’s disease and cancer.
Unfortunately, it’s impossible to avoid free radicals. Not only are they a byproduct of normal metabolic functions (like breathing), but we’re also exposed to them as a result of environmental factors (pesticides, pollution, ultraviolet light and cigarette smoke), poor dietary choices (fried/processed/sugary foods and alcohol) and even stress.
Free radicals are so unstable because they lack a single electron. In order to achieve stability, they strip away electrons from normal molecules—at the same time damaging the DNA of those once-healthy cells. This process creates new free radicals that go on the prowl for electrons to steal from other stable molecules. It’s a chain reaction that ravages countless healthy cells along the way.
Our bodies have a built-in defense mechanism against free radicals—antioxidants. You’ve probably heard about the powers of antioxidants. They neutralize and stabilize free radicals, putting an end to their vicious journey before the destruction gets out of control.
Your body produces antioxidants on its own, but you can also get them from many of the foods you eat and by taking antioxidant supplements such as astaxanthin, resveratrol and vitamins A, C and E.
So, given this information, you could probably confidently conclude that antioxidants are extremely beneficial because they promote good health and prevent diseases that result from oxidative/DNA damage.
But a recent study has shed some doubt on the value of antioxidants—especially vitamin E—when it comes to protecting against one particularly deadly disease: lung cancer. In fact, according to this study, antioxidants actually accelerate the growth of lung tumors.1
Let’s first take a closer look at this study because, as with so many things in life, the devil is in the details.
While conducting some unrelated experiments using mice that were genetically engineered to develop lung cancer, researchers gave some of the mice N-acetyl cysteine (NAC), thinking it might slow tumor growth. (NAC is a precursor to glutathione, a powerful antioxidant that contains sulfur compounds—sticky substances that “catch” and eliminate harmful things floating in the body, including free radicals, heavy metals and other toxins.)
After 10 weeks, the mice were sacrificed and the researchers discovered that the ones given supplemental NAC had almost three times the tumor burden as the controls.
The researchers expanded their study to test the effect of vitamin E supplementation as well. The mice were given vitamin E, NAC or nothing (control). In this experiment, both antioxidants produced similar results: Compared to the controls, the treated mice had more tumors, and their tumors grew about three times quicker. The effect appeared to be dose-dependent—the higher the dose, the bigger the tumors and more rapid the growth. The treated mice also died twice as fast as the controls.
When digging deeper to learn the hows and whys of this discovery, the researchers confirmed that the antioxidants did indeed decrease DNA damage in cells—so much so that malignancies became almost undetectable, even though the cancer did not completely disappear. When significant cancer-causing DNA damage goes undetected, the body reigns in its defense system against cancer—a protein called p53, whose main responsibility is suppressing the growth of tumors. So, according to these researchers, vitamin E and NAC actually helped the lung cancer avoid detection by p53 proteins, allowing these malignant cells to grow and thrive.
Not All E Is Created Equal
This isn’t the first time research has called into question the effectiveness or safety of antioxidants, particularly vitamin E, and lung cancer. But, with that said, plenty of other studies have demonstrated that vitamin E may actually protect against lung cancer.
A 2008 study of 1,088 patients with lung cancer and 1,414 healthy controls showed that taking natural vitamin E (alpha-, beta-, gamma- and delta-tocopherols) can reduce lung cancer risk by 61 percent.2
A more recent 2013 study stated that vitamin E has “demonstrated strong association with the prevention of cancer and the inhibition of tumor, both in vitro and in vivo.” Furthermore, “vitamin E presented efficiency against specific subhistology types of lung cancer.”3
So why these discrepancies? It could very well amount to one seemingly insignificant factor—the type of vitamin E used.
Vitamin E is comprised of eight different fat-soluble compounds, divided into two groups: tocopherols and tocotrienols. Each of these two groups contain four forms of vitamin E, which start with alpha-, beta-, gamma- and delta-.
All vitamins work synergistically—and E is no exception—so for maximum benefits, you should use a full-spectrum formula that contains all eight of these subgroups, often referred to as “mixed natural tocopherols and tocotrienols.”
Note the word natural.
Unbeknownst to many supplement buyers, synthetic vitamin E is far more prevalent than natural vitamin E. You can note the difference between natural and synthetic by looking at the supplement’s label. Naturally sourced nutrients are listed with a “d-” prefix (such as d-alpha-tocopherol), while synthetic versions start with “dl-” (dl-alpha-tocopherol).
Rather than being sourced from plant materials that naturally contain the vitamin, synthetic vitamin E is manufactured in a lab with chemicals and additives, and engineered to mimic the way the natural version works in the body. Synthetic vitamins also lack important enzymes and other components (“co-factors”) that help the body recognize and metabolize them correctly.
Simply put, synthetic vitamin E is inferior to natural—and the body is smart enough to know the difference. It absorbs and utilizes natural forms of vitamin E far better and more efficiently than synthetic. In fact, synthetic vitamin E is often rejected and excreted up to three times faster than natural—often leeching other vital vitamins and minerals on its way out.4
More importantly, research indicates that synthetic varieties of vitamin E, especially in high doses, can potentially do more harm than good. After all, if you isolate a lab-made vitamin from the co-factors that make it recognizable to the body, it only makes sense that the body treats and attacks it like an imposter. Studies dating back to the mid-1990s show that synthetic vitamin E can increase risk of various cancers, including prostate and pancreatic.5-6
Knowing this, is it any surprise that the vitamin E used in the most recent negative lung cancer study was dl-alpha-tocopherol acetate? That’s right…synthetic.
NAC Is Also Not the Enemy
It’s not all bad news for NAC, either.
This compound has been shown to induce cancer cell apoptosis (death)7 and prevent cancer cells from replicating.8 It also inactivates c-Src, a molecule associated with cancer growth and progression.9
And when it comes to lung cancer specifically, a 2010 study examined the efficacy of three different chemopreventive agents—one of which was NAC—in mice exposed to cigarette smoke for 120 consecutive days. The smoke resulted in benign lung tumors in some of the mice and malignant lung tumors in others. The researchers noted that all three of the agents used “were quite effective in protecting both male and female mice from cigarette smoke pulmonary carcinogenicity.” They concluded, “The proposed experimental model provides convincing evidence that it is possible to prevent cigarette smoke-induced lung cancer by means of dietary and pharmacological agents.”10
This finding could have tremendous implications for ex-smokers as well as people overexposed to secondhand smoke, but more research in humans is warranted.
What to Make of this Study
So what should you make of this negative vitamin E/NAC study? Would it be prudent to stop supplementing these antioxidants based on these results?
Along with the natural/synthetic issue, there are a couple other considerations to keep in mind.
First, mouse studies don’t always translate to humans. So these results are preliminary at best and merit further investigation.
Second, the mice were genetically programmed to develop aggressive tumors, then given very high antioxidant doses—equivalent human doses of up to 10,000 IU vitamin E. (The recommended daily allowance for adults is 15 mg or 22.4 IU, with tolerable upper intake levels at 1,000 mg or 1,500 IU.11) Extremely high amounts of any drug or supplement can lead to unpredictable and dangerous consequences. More is not always better.
Finally, when it comes to fighting free radical damage, we know that antioxidants are the undisputed leader of the pack. However, it’s important to remember that the body can usually do an excellent job of upping its antioxidant levels and neutralizing free radicals if you provide it with healthy, nutrient-dense foods while limiting your intake of alcohol, artificial sweeteners and fried, processed and sugary foods. Avoiding tobacco and other drugs, as well as reducing chronic stress, are also critical.
Increasing your consumption of certain foods can naturally raise vitamin E levels in your blood and up your antioxidant power. Major sources include various oils (olive and sunflower are good bets); nuts (almonds, hazelnuts and peanuts); and green leafy vegetables (spinach is highest). Avocado is also fairly rich in E.
If you find that you don’t eat enough of these foods on a regular basis, then supplementing with natural vitamin E would probably be a good idea. Most Americans don’t get even the daily recommend amount of vitamin E anyway. Be sure to look for the “d-“ prefix to ensure it’s naturally sourced. Taking 200-400 IU per day should suffice.
As for NAC, no food sources exist. But the body converts NAC first to cysteine, then to glutathione—and cysteine is present in high-protein foods such as chicken, pork, turkey, duck, fish, eggs and dairy. So adding more protein to your diet from these sources would be helpful to boost the antioxidant glutathione. If you do choose to supplement NAC, use a safe, preventive dose—usually around 600 mg per day.
- Sayin VI, et al. Sci Transl Med. 2014 Jan 29;6(221):221ra15.
- Mahabir S, et al. Int J Cancer. 2008 Sep 1;123(5):1173-80.
- Zarogoulidis P, et al. J Thorac Dis. 2013 Jun;5(3):349-52.
- Traber MG, et al. FEBS Lett. 1998 Oct 16;437(1-2):145-8.
- Klein EA, et al. JAMA. 2011 Oct 12;306(14):1549-56.
- Rautalahti MT, et al. Cancer. 1999 Jul 1;86(1):37-42.
- Guan D, et al. Mol Carcinog. 2010 Jan;49(1):68-74.
- Li J, et al. Eur J Gastroenterol Hepatol. 2007 Sep;19(9):769-74.
- Krasnowska EK, et al. Free Radic Biol Med. 2008 Dec 1;45(11):1566-72.
- Balansky R, et al. Int J Cancer. 2010 Mar 1;126(5):1047-54.
- Institute of Medicine. http://iom.edu/Activities/Nutrition/SummaryDRIs/~/media/Files/Activity%20Files/Nutrition/DRIs/New%20Material/4_%20UL%20Values_Vitamins%20and%20Elements.pdf.