Antioxidants, Part 1 - What role do antioxidants and free radicals play in health and disease?

Antioxidants are thought to provide protection from damage to cells in the body from unstable molecules known as free radicals. Examples of antioxidants include vitamins (beta-carotene, C, E, and A) and carotenoids (lycopene and lutein). In addition, the mineral selenium, while not technically an antioxidant, is a component of important antioxidant enzymes, and is often mentioned as an antioxidant.

Free radicals are produced as a by-product of normal cell metabolism, such as when our bodies covert food into energy. They can also enter our bodies from exposure to tobacco smoke, pollution, and radiation from the sun and x-rays. When free radicals build up in cells, damage to DNA can occur. Damage to cellular DNA has been linked to the development of cancer and cardiovascular disease. Additionally, certain age-related disease, such as Alzheimer's and Parkinson's disease, may also be influenced by free radical-induced damage. By neutralizing free radicals, antioxidants are believed to provide protection against the development or progression of these diseases. It should be noted, however, that free radicals also participate in some health-promoting activities, such as killing germs while assisting with wound healing.

Antioxidants and cancer: While the general perception among the public is that antioxidants are beneficial, research into the effect of antioxidants on cancer has been mixed. The National Cancer Institute summarized the results of the major research into the effect of beta-carotene and other antioxidants in cancer prevention as follows:

• The first large randomized trial on antioxidants and cancer risk was the Chinese Cancer Prevention Study, published in 1993. This trial investigated the effect of a combination of beta-carotene, vitamin E, and selenium on cancer in healthy Chinese men and women at high risk for gastric cancer. The study showed a combination of beta-carotene, vitamin E, and selenium significantly reduced the incidence of both gastric cancer and cancer overall.


• A 1994 cancer prevention study entitled the Alpha-Tocopherol (vitamin E)/ Beta-Carotene Cancer Prevention Study (ATBC) demonstrated that lung cancer rates of Finnish male smokers increased significantly with beta-carotene and were not affected by vitamin E.


• Another 1994 study, the Beta-Carotene and Retinol (vitamin A) Efficacy Trial (CARET), also demonstrated a possible increase in lung cancer associated with antioxidants.


• The 1996 Physicians' Health Study found no change in cancer rates associated with beta-carotene and aspirin taken by U.S. male physicians.


• The 1999 Women's Health Study (WHS) tested effects of vitamin E and beta-carotene in the prevention of cancer and cardiovascular disease among women age 45 years or older. Among apparently healthy women, there was no benefit or harm from beta-carotene supplementation. Investigation of the effect of vitamin E is ongoing.

Antioxidants and Cardiovascular Disease: Free radicals, acting on low-density lipoproteins (bad cholesterol), has been considered a leading cause of atherosclerosis (the development of fatty buildup in the arteries). Over time, atherosclerosis can lead to heart attacks and strokes. Clinical trials have been conducted to determine if antioxidants could prevent damage to the vessels and the development of cardiovascular disease.

As with the studies evaluating the effect of antioxidants on cancer, the results of research looking at the benefits of antioxidants in treating or preventing cardiovascular disease has not been conclusive. A review of the literature published in the journal of the American Heart Association found:

• Ten studies that showed no effect of taking antioxidants (vitamin E, vitamin C, and/or beta-carotene) on cardiovascular disease events (e.g. heart attack).


• Five studies that demonstrated a protective effect against the development of heart attacks in patients with known heart disease or increased heart attack risk when taking antioxidants (vitamin E and/or vitamin C)


• Five studies that showed an increased risk of adverse effects (e.g. stroke, progression of arterial blockage, and death from all causes) in the study group that took various antioxidants.

The conclusions drawn by the authors of this review of the literature was that "the existing scientific database does not justify routine use of antioxidant supplements for the prevention and treatment of cardiovascular disease."

While there are a number of theoretical benefits to taking antioxidants, current research has yet to provide convincing evidence of their effectiveness. A few of the reasons for this include the specific antioxidant (or its dosage) that was being tested, the source of the antioxidant (supplements vs. food), and the specific type of disease that was being studied. Nevertheless, because of the potential benefits, many authorities continue to advise that people take antioxidants and in next week's Health Tip, we'll look at some of the best sources.

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Use of potassium iodide in radiation exposure

Following the seismic events that damaged several nuclear reactors in Japan, many Americans are concerned about the possibility of exposure to radiation drifting across the Pacific Ocean with the prevailing winds. This has resulted in a buying frenzy of potassium iodide tablets, a known deterrent to certain effects of radiation on the body. In situations such as these, however, it is prudent to listen to experts monitoring radiation levels to learn the likelihood of being exposed and to understand what can and cannot be done in regard to radiation exposure.

What is potassium iodide (KI)? Potassium iodide is a salt form of iodine, whose primary function in the body is to help make thyroid hormone. Concentrated food sources of iodine include kelp (seaweed), shellfish, cow's milk, and eggs. Potassium iodide is often added to table salt to produce "iodized" salt, which serves primarily to provide a source of iodine for the body. Potassium iodide is available in tablet and liquid form. One form of potassium iodide called SSKI is used by people with emphysema as an expectorant to help loosen and break up mucus in the airways.

How does potassium iodide help with radiation exposure? With the release of gases following a nuclear accident such as occurred recently in Japan, radioactive iodine can enter the body through the lungs. Since the thyroid gland concentrates both radioactive as well as stable iodine, high levels of radiation can develop in the thyroid gland. Over time, this can lead to the development of thyroid cancer. Potassium iodide, if taken in time and at the proper dosage, can block the absorption of radioactive iodine by the thyroid and prevent cancer from occurring.

What potassium iodide does not do. There are a number of potentially damaging effects of radiation on the body. The development of thyroid cancer is only one of these. Potassium iodide provides protection only for the thyroid gland. Depending on the amount of radiation absorbed by the body, the type of radiation, the route of exposure, and the length of time a person was exposed, other adverse health effects range from skin reddening to acute radiation syndrome (ARS), which can result in death.

Is there any harm in taking potassium iodide? Potassium iodide should only be taken when the risk of exposure to radiation warrants its usage. In the case of a radiation emergency, the benefits of taking potassium iodide are believed to outweigh the risk. As with any other medication or supplement, however, adverse effects can occur with taking potassium iodide. Those people with a known allergy to iodine should not take potassium iodide. Additionally, anyone with an existing thyroid condition (Grave's disease, goiter, thyroiditis, etc.) should only take it under the guidance of a physician. Other side effects of potassium iodide include intestinal upset, rashes, and inflammation of the salivary glands.

Current recommendations. A few days ago, the U.S. Nuclear Regulatory Commission released the following statement, "Given the thousands of miles between the two countries, Hawaii, Alaska, the U.S. Territories and the U.S. West Coast are not expected to experience any harmful levels of radioactivity." With that in mind, most authorities believe that taking potassium iodide is unnecessary at this time.

Since the situation in Japan is still unfolding, we need to remain vigilant regarding the potential for radiation exposure. For more information on the effort by the U.S. government to monitor radiation levels and inform the general public, go to the Environmental Protection Agency's sites: Japan Nuclear Emergency:
Frequently Asked Questions or RadNet.

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Laryngopharyngeal Reflux (Silent Reflux)

Laryngopharyngeal Reflux (LPR) refers to the backflow of stomach acid up the esophagus and into the larynx (voice box) or the pharynx (throat). It is sometimes called silent reflux because, unlike typical gastroesophageal reflux, LPR can occur without heartburn or indigestion. This is because the stomach acid does not stay in the esophagus long enough to irritate the esophagus and cause heartburn. What causes LPR? Stomach acid that is produced to help with digestion of food is prevented from backing up into the esophagus by a ring of muscle at the entrance of the stomach known as the lower esophageal sphincter. If this sphincter is not functioning well, stomach acid can backflow into the esophagus. LPR occurs when stomach acid backs up the entire length of the esophagus and enters the throat and voice box. How would you suspect that you could have LPR? The predominant symptoms of LPR affect the throat and voice box. These symptoms include: Hoarseness A "lump" in the throat Trouble swallowing Chronic cough Thick or excessive throat mucous Chronic throat clearing In addition to these symptoms, some people with LPR also have the typical gastroesophageal reflux symptoms of heartburn and indigestion. How is LPR diagnosed? Because LPR is often silent, it can be difficult to diagnose. If your doctor suspects that you have LPR, he/she will probably perform a throat exam first and look at the voice box and the lower throat. Redness and swelling in this area is highly suggestive of LPR. In order to confirm the diagnosis, endoscopy and/or pH monitoring may be performed. Endoscopy involves the use of a viewing instrument called a laryngoscope to look at the voice box and throat. pH monitoring is a procedure in which a small, flexible tube is placed through the nose and into the throat and esophagus. This tube is left in place for a 24-hour period, measuring the amount of acid that enters the throat. How is LPR treated? The three general methods for treating LPR are 1) changing habits and diet to reduce reflux, 2) taking medications to reduce stomach acid, and 3) undergoing surgery to prevent reflux. Of these treatment options, addressing lifestyle habits that may be contributing to acid reflux is the simplest, safest, and least expensive method. Tips for reducing reflux and LPR: If you use tobacco, quit. Don't eat at least 3 hours before going to bed. Lying down shortly after eating is especially bad for someone who has reflux. Minimize fried, fatty and spicy foods in your diet. Certain foods including chocolate, peppermint, onions, acidic fruit juices, and garlic are notorious for causing reflux. Avoid tight clothing, especially around the waist. If needed, lose weight. Cut out caffeine, specifically coffee, tea, and caffeinated soft drinks. Avoid alcoholic beverages, particularly in the evening. In addition to these measures, many people with LPR benefit from elevation of the head of the bed by 4 to 6 inches by placing wood or cinder blocks under the headboard. This keeps acid in the stomach where it belongs through "gravity". Placing several pillows under your head does not substitute for raising the head of the bed; in fact, this maneuver can make the problem worse. Many people with LPR will require a medication to reduce reflux or to neutralize stomach acid. These include proton pump inhibitors (Prilosec, Prevacid, Protonix), H2 blockers, (Pepcid, Tagamet, Zantac), and Antacids (Maalox, Mylanta). Surgery is reserved for the most severe cases of reflux. The most commonly performed procedure for this is called a "fundoplication", in which the lower esophageal sphincter is tightened to prevent stomach acid from entering the esophagus. How long is treatment usually necessary? LPR is somewhat like high blood pressure in that it is a condition that is usually "managed" rather than "cured". In other words, most people with LPR will need to pay attention to lifestyle measures or take medications indefinitely.

How well do popular supplements work for treating colds?

The common cold is a viral infection of the upper respiratory system. On average, children have six to eight colds per year, and adults have two to four. The common cold places a heavy burden on society, accounting for approximately 40% of time taken off work and millions of days of school missed by children each year. While medical science has yet to develop a cure for the common cold, many people take a variety of supplements in the hopes that they will shorten the duration of the illness. The most popular of these supplements are zinc, vitamin C, and Echinacea. Let's look at some of the scientific evidence of the effectiveness of these supplements. Much of this information comes from the Cochran Group, an international network of scientists who compile the work of several researchers into larger studies known as "metanalyses". By pooling data from a number of well-conducted studies, more robust and accurate conclusions can be drawn. Zinc is commonly sold as a natural medicine for colds in tablet, lozenge, and liquid form. It is thought to decrease the ability of cold viruses to grow on or bind to the lining of the nose. While the results of studies have gone back and forth over the years regarding zinc's effectiveness in treating colds, a recent Cochran analysis supports the evidence for zinc supplementation in treating colds. After pooling the results of several well-conducted studies, the following conclusions were drawn: If started within 24 hours of the onset of cold symptoms, zinc supplementation was found to reduce the duration of colds by about a day on average. People taking zinc were around half as likely to have symptoms after a week and had less severe symptoms than people taking a placebo. When continued for at least five months, taking zinc supplements reduced the number of colds that developed, school absenteeism, and prescription of antibiotics in children Because the dosages and duration of treatment with zinc varied across the various studies evaluated, it was impossible for the authors to specify a particular dosage or treatment period that appeared to be most effective. Furthermore, the authors warned that there was a potential for zinc supplementation to cause side effects, such as nausea. In 2009, the U.S. Food and Drug Administration warned consumers to stop using intranasal zinc products (zinc-containing homeopathic cold remedies), because of reports of anosmia (loss of smell). Excluding vitamins and minerals, Echinacea is one of the most commonly used natural supplements. Advocates say that it is can boost the immune system and has antiviral properties, such as preventing colds. However, two 2006 metanalyses evaluating this natural remedy drew conflicting conclusions. In the first analysis, extracts of Echinacea were found to be effective in preventing cold symptoms if someone had been clinically inoculated with the cold virus. The second, a Cochrane Systematic Review, found no evidence that Echinacea was any better than a placebo at preventing the common cold. Three clinical trials funded by the National Center for Complementary and Alternative Medicine found no benefit from Echinacea for preventing or treating colds. Echinacea products vary widely, with different preparations using different species of the plant as well a different plant parts. The final word on the effectiveness of this supplement awaits further research. Vitamin C is an important micronutrient and antioxidant. The role of vitamin C in the prevention and treatment of the common cold has been a subject of controversy for decades. Nevertheless, it is widely used as both a preventive as well as therapeutic supplement. A 2007 analysis of results from 30 clinical trials involving 11,350 participants found that taking vitamin C regularly (200 milligrams or more daily) found that: When taken after a cold starts, vitamin C supplements did not make a cold shorter or less severe. When taken on a daily basis as a preventive measure, vitamin C could slightly shorten the duration of a cold. In other words, the average adult who suffers with a cold for 12 days a year would still suffer for 11 days a year if that person took a high dose of vitamin C every day during that year. Vitamin C supplementation could be justified in people exposed to brief periods of severe physical exercise (e.g. running a marathon) or to cold environments. In those people, taking vitamin C appeared to cut their risk of catching a cold in half. Since the final word regarding these and other supplementsin the treatment of the common cold is still not clear, a better approach would be to prevent the cold from developing in the first place. The best methods for doing so appear to be "behavioral" in nature, such as washing your hands regularly, getting plenty of rest, limiting exposure to people with colds, and avoiding touching your nose or eyes with potentially contaminated hands. If you have any questions about the prevention of colds, please log into your account and send us your question. We are glad to help.