Do Antioxidants Prevent Cancer?

It's easy to recommend fruits and vegetables as a source of antioxidants. Observational studies have consistently shown an association between diets high in fruits and vegetables and a lower risk of cancer and heart disease. However, I'm often asked about taking antioxidants as supplements. Pills are easier to take in our time-starved society.

Several studies have been done to determine the role of supplements in reducing the risk of cancer and cardiovascular disease, but the results have been mixed. In a recent paper in the Mayo Clinic Proceedings a systematic review of 12 randomized clinical trials was done to evaluate the effect of antioxidants on cancer incidence and cancer deaths. These trials studied Vitamins C and E, betacarotene, selenium, zinc and lycopene. The majority of the trials included a population of at least 10,000 subjects.

The review concluded that overall there was no reduction in the total number of cancers or in the number of deaths due to cancer. However, in breaking down the data by antioxidants, there were a few antioxidant specific findings. Beta carotene was associated with a slightly higher risk of cancer in smokers. Vitmain E had no effect on cancer incidence or mortality. Selenium was associated with a borderline reduction in cancer incidence and mortality, but this effect was mainly seen in men.

Bottom line is that it may be best to get your antioxidants from food and not from pills.

Photo: courtesy of balanced living.

What Families Eat Around the World.

Take a look at these pictures and notice what's lacking in the American family's week of food compared to the other countries. In case you can't spot it because you haven't had enough of it lately - it's produce - fruits and vegetables.

For more details on the gathering of this information and a breakdown of the foods see this NPR interview with the authors of Hungry Planet: What the World Eats.

Top Ten Recommendations for Reducing Cancer Risk

The World Cancer Research Fund (WRFC) recently published their recommendations for reducing cancer risk. The report is based on a comprehensive review of 7000 studies which were conducted worldwide since the 1960's. It is an update from the 1997 report initially published by WFRC and the American Institute for Cancer Research.

The report links weight, exercise, diet, and cancer risk. It concludes that body fat level is closely associated with the risk of developing cancer. Apparently putting on weight can increase cancer risk even if you are still within the healthy range. The closer you are to the lower end of your ideal weight range the lower is your risk of developing cancer. There are no magic elixirs, not even supplements that were proven to be useful for preventing cancer. The good news, however, is that you do have control over many of the factors that contribute to the risk of cancer.

The panel's recommendations based on the extensive review of the literature are the following:
1. Be as lean as possible without becoming underweight. (Ideal weight calculator).
2. Be physically active for at least 30 minutes every day.
3. Avoid sugary drinks. Limit consumption of energy-dense foods (particularly processed foods high in added sugar, or low in fibre, or high in fat).
4. Eat more of a variety of vegetables, fruits, whole grains and pulses such as beans.
5. Limit consumption of red meats (such as beef, pork and lamb) to 750 grams a week, and avoid processed meats.
6. If consumed at all, limit alcoholic drinks to 2 for men and 1 for women a day.
7. Limit consumption of salty foods and food processed with salt (sodium).
8. Don’t use supplements to protect against cancer.
9. It's best for mothers to breastfeed exclusively for up to 6 months and then add other liquids and foods.
10. After treatment, cancer survivors should follow the recommendations for cancer prevention. 10. Don't smoke or chew tobacco.

Here's an interview with one of the authors of the report.

Omega 3, Fish and Mercury - Is Fish Safe to Eat?

Omega-3 fatty acids have been reported to have a beneficial effect on cardiovascular disease (CVD) . This effect has been reported in patients with preexisting CVD as well as in healthy individuals. A number of countries (Canada, Sweden, United Kingdom, Australia, Japan) as well as the World Health Organization have made formal population-based dietary recommendations for omega-3 fatty acids.

Foods that are rich in omega 3 fatty acids include fish, canola and olive oil, soy, flax seed, and walnuts. Most of the studies which show the health benefits of omega 3 have been correlated with fish consumption. Omega 3 fatty acids can be categorized into plant-derived omega 3 fatty acids ( -linolenic acid) and marine-derived (eicosapentaenoic acid [EPA] and docosahexaenoic acid[DHA]) omega-3 fatty acids. Typical recommendations for daily intake of linolenic acid are 0.8 to 1.1 g. Recommendations for EPA and DHA are 0.3 to 0.5 g/d and up to 1.2 grams if there is a history of heart disease or cholesterol abnormality.

Fish are the major food source of EPA and DHA. All fish contain EPA and DHA. However, some species of fish may contain significant levels of methylmercury, polychlorinated biphenyls (PCBs), dioxins, and other environmental contaminants. Exposure to PCBs can be reduced by removing the skin and fat from these fish before cooking them; however, because mercury is distributed throughout the muscle it is not possible to remove it from the filet. Fish that are highest in mercury concentration are the large predatory fish such as swordfish, King mackerel, shark, and tilefish. This chart shows the different levels of mercury associated with different types of fish.

The benefits and risks of eating fish vary depending on a person’s stage of life. In general it is advised that children and pregnant and nursing women avoid potentially contaminated fish because this group is at a lower risk for cardiovascular disease but at a higher risk of exposure to mercury. For middle-aged and older men, and women after menopause, however, the benefits of eating fish far outweigh the risks within the established guidelines . Eating a variety of fish will help minimize any potentially adverse effects due to environmental pollutants.

Here's a video about omega 3 from a medical student.

References: Circulation. 2002;106:2747. U.S. Environmental Protection Agency. American Heart Association.

What's Wrong with Trans Fatty Acids

The New York City Board of Health has recently required that restaurants reduce the content of trans fatty acids so that each serving contains less than 0.5 grams. A recent study in the New England Journal of Medicine showed that a 2% increase in caloric intake from trans fatty acids was associated with a 23% increase in the incidence of coronary artery disease. The association is stronger with heart disease than it is with saturated fats.

What are trans fatty acids? Naturally occuring fats consist of saturated and unsaturated fatty acids. Unsaturated oils (vegetable oils) are converted to the trans form by partial hydrogenation to increase their stability and to raise the melting point. This process converts vegetable oils into semisolid fats for use in margarines, commercial cooking, and manufacturing processes.

Why are trans fatty acids bad for you? Previously it was assumed that trans fatty acids would be healthier than saturated fats, but they have been shown to decrease HDL cholesterol (the good cholesterol) and increase LDL cholesterol (the bad cholesterol). They also cause damage to the lining of blood vessels. In addition they have shown to promote abdominal fat depostion and insulin resistance both of which are early changes in the development of type 2 diabetes.

Where are trans fatty acids found? Deep fried food, packaged snacks, and bakery products are the major sources of trans fatty acids in the US. The average daily intake in the US is about 2.6 % or 6 grams in a typical 2000 calorie diet. The American Heart Association recommends limiting intake of trans fatty acids to 1% of daily caloric intake. Deep fried fast-food products may include 10 grams per serving.

How to avoid the bad fats? The American Heart Association recommends the following:

--Choose a diet rich in fruits, vegetables, whole-grain, high-fiber foods, and fat-free and low-fat dairy most often.
--Keep total fat intake between 25 and 35 percent of calories, with most fats coming from sources of monounsaturated and polyunsaturated fats such as fish, nuts, seeds and vegetable oils most often.
--Use naturally occurring, unhydrogenated vegetable oils such as canola, safflower, sunflower or olive oil most often.
--Look for processed foods made with unhydrogenated oil rather than partially hydrogenated or hydrogenated vegetable oils or saturated fat.
--Look for ”0 g trans fat” on the Nutrition Facts label.
--French fries, doughnuts, cookies, crackers, muffins, pies and cakes are examples of foods that are high in trans fat. Don't eat them often.
--Limit the saturated fat in your diet. If you don't eat a lot of saturated fat, you won't be consuming a lot of trans fat.
--Limit commercially fried foods and baked goods made with shortening or partially hydrogenated vegetable oils. Not only are these foods very high in fat, but that fat is also likely to be very hydrogenated, meaning a lot of trans fat.
--Commercial shortening and deep-frying fats will continue to be made by hydrogenation and will contain saturated fat and trans fat. That's just one more reason to eat fried fast food infrequently.

References: The Medical Letter, vol 49 (issue 1267), August 13, 2007. Please see above links.

Photo: courtesy of University of Pennsylvania Health Systems.

Sodas and Heart Disease?

There have been several news reports since yesterday on the findings of a study which concluded that people who drink more than one soda a day - diet or regular- have a higher chance of heart disease.

I'm not a big fan of sodas, but since diet sodas help reduce the daily calorie intake, I'm concerned that people who consume diet sodas will come to the wrong conclusion based on the superficial news coverage of this study. The data does not show any cause and effect. It simply demonstrates an association. It may be that people who are drinking sodas are already following a less healthy lifestyle and therefore have a higher association with heart disease. Given the epidemic of obesity and its impact on heart disease and diabetes, it seems that the risk benefit ratio is still in favor of the diet sodas.

As for regular sodas, there is no reason to drink them as far as I'm concerned.

References: please see links.

Helping You Eat Your Fruits and Veggies

Healthy People 2010 objectives include increasing the number of people who are eating fruits and vegetables since there is significant evidence that proper nutrition may help decrease the risk of certain cancers and cardiovascular disease. As part of this campaign, here are a few good websites that hopefully will encourage you to eat more fruits and vegetables. They have lots of good tips and recipes, and help determine the amount of fruits and vegetables that is recommended for any age, sex, and physical activity level.

http://www.5aday.gov
http://www.fruitsandveggiesmorematters.org
http://www.eatright.org

Photo: courtesy of discovery.com

Fruit and Vegetable Juices and Alzheimer's Disease

Here's another reason to drink your V-8 or any other vegetable or fruit juice of your choice. A recent study published in the American Journal of Medicine, concluded that the risk for Alzheimer's disease was reduced among people who drank fruit and vegetable juices, three or more times a week compared with those who drank these juices less than once per week.

The polyphenols in fruits and vegetables may offer stronger neuroprotection than antioxidants in vitamin pills. Polyphenols from apple and citrus juices, such as querctin, cross the blood-brain barrier and protect the brain cells against hydrogen peroxide. Hydrogen peroxide is believed to mediate the oxidative reaction caused by beta amyloid peptide which leads to Alzheimer's disease.

References: please see specific links.
Photo: courtesy of Hong Kong Food.

Saved by Chocolate?

If you are going to eat chocolate, which is very likely during this time of year, then I might as well give you some good news about it. A recent study at Johns Hopkins University inadvertently found that just a few squares of dark chocolate a day may reduce the risk of heart attack by decreasing the tendency of platelets to clot.

The study, Genetic Study of Aspirin Responsiveness (GeneSTAR), was designed to study the antithrombotic effect of aspirin. The subjects were given instructions to exercise, stop smoking and avoid certain foods such as chocolates. However, the chocolate addicts in the group did not comply. When this was discovered, they were ejected from the study, but their blood samples were examined for the effects of chocolate on platelets. The samples from both the compliant and the non-compliant subjects were run through a mechanical blood vessel system designed to time how long it takes for the platelets to clump together in a hair-thin plastic tube. The chocolate lovers' platelets on average took 130 seconds to occlude the system. The other group's platelets clotted faster at 123 seconds.

This anti-thrombotic effect may explain some of the cardioprotective effects of chocolates which have been reported in the past. However, it should be noted that this study is not a carte blance for going chocolate crazy. The benefits of chocolate are attributed to the cocoa bean and not to its other calorie busting ingredients such as cream and sugar. As always moderation and balance are keys to a healthier life style.

Reference: Johns Hopkins Medicine

I Can't Believe I Ate the Whole Thing

The day after Thanksgiving is not only the beginning of the shopping season, but it's also the beginning of the heartburn season.

Heartburn is the sensation of pain, burning, or pressure in your chest which usually occurs after a meal especially a large or rich meal. Other symptoms include a sour taste in the mouth, regurgitation of the food, hoarseness, difficulty swallowing, sore throat, coughing, or wheezing.

Heartburn is a symptom of gastroesophogeal reflux disease (GERD) which is caused by a back flow of stomach acid into the esophagus. This is due to a weakening of the valve, the lower esophageal sphincter, which normally holds the stomach content in place. Factors contributing to GERD or heartburn are the following:

• Alcohol use
• Overweight
• Smoking
• Pregnancy
• Certain foods such as chocolate, caffeine, garlic, onions, mint, citrus or spicy foods.
• Large meals, or lying down or bending down after a meal.

There are several over the counter medications available to treat heartburn. This gives an idea of how common the condition is.

• Antacids such as Maalox, Mylanta, or Tums are fast acting because they neutralize the acid, but their effect is short lived.
• H-2-receptor blockers such as Zantac (ranitidine), Tagamet (cimetidine), or Pepcid (famotidine) reduce the amount of acid production. They take a bit longer to work, but they provide a longer duration of relief of symptoms.
• Proton pump inhibitors such as Prilosec (omeprazole) stop acid production. Omeprazole is the only one that is currently available over the counter. This is usually used in more persistent cases and to allow healing of the esophagus.

Heartburn is common. It is considered benign if it occurs less than 3-4 times a month. In these cases simple lifestyle changes which avoid the triggers or taking antacids takes care of the problem.

However, if the symptoms are occurring on a regular basis, if they are not resolving with the usual over the counter medications, or if they are waking you up at night then you should contact your doctor. Heartburn symptoms could also signal more serious conditions such as an ulcer or esophagitis (irritation of the lining of the esophagus).

If untreated, the prolonged exposure to the acid can damage the lining of the esophagus and lead to a condition called Barrett's esophagus. This condition is associated with an increased risk of esophageal cancer. It is uncommon and the risk of developing cancer is about 1% per year, but regular follow up with a physician is necessary if this condition is diagnosed. It may only be diagnosed by an upper endoscopy.

Finally it should be noted that the pain of a heart attack may present like heartburn. If you have other risk factors for heart disease such as obesity, smoking, high blood pressure or high cholesterol, of if this is your first episode of heartburn type symptom then contact your doctor for advice.

References: please see links.
Photo: courtesy of overeating.

Serving Size

The food pyramid post raised the question of what is a serving size. A general guideline is that a serving size is the portion that can fit in the palm of your hand. Yes, the portions are bigger if you have bigger hands. More quantitative measures are given by the USDA (see link for details) and the American Cancer Society.

The following is the ACS suggested serving sizes for fruits, vegetables and other foods in case you are keeping count in your diet.


Fruits:
1 medium apple, banana, orange
1/2 cup of chopped, cooked, or canned fruit
1/2 cup of 100% fruit juice

Vegetables:
1 cup of raw leafy vegetables
1/2 cup of other cooked or raw vegetables, chopped
1/2 cup of 100% vegetable juice

Grains:
1 slice bread
1 ounce ready-to-eat cereal
1/2 cup of cooked cereal, rice, pasta

Beans and nuts:
1/2 cup cooked dry beans
2 tablespoons peanut butter
1/3 cup nuts

Dairy foods and eggs:
1 cup milk or yogurt
1 1/2 ounces of natural cheese
2 ounces processed cheese
1 egg

Meats:
2–3 ounces of cooked lean meat, poultry, fish

Reference: American Cancer Society's Guidelines on Nutrition and Physical Activity for Cancer Prevention.
Photo: courtesy of http://www.diabetes.org.nz/pics/portionsize.jpg

MyPyramid Presentation

My Pyramid Tracker (http://www.mypyramidtracker.gov/default.htm) is a free site from the U.S. Department of Agriculture. It analyzes your food intake and makes recommendations based on the 2005 Dietary Guidelines for Americans. I was testing it to see if I should recommend it to the bloggers when I found out that my pyramid is quite lopsided. The analysis showed that for the last 24 hours my calorie intake was twice as much as my energy expenditure and my grain intake was 273% of the recommended intake. This could make for a very out of shape "pyramid". You may want to check out the link to see how you fare in the world of nutrition.

Green Tea, The Ohsaki Study

There have been many reports on the protective effects of green tea polyphenols against heart disease and cancer, but these reports are mostly based on in-vitro and in animal studies. The Ohsaki Study was designed to investigate the effect of drinking green tea in more than 40,000 Japanese adults aged 40 to 79 years to see if the benefits could be confirmed in humans. These subjects were studied for 11 years (1995-2005).

The main outcome evaluated was death due to cardiovascular disease or cancer, and all cause mortality. The researchers for this large population-based, prospective cohort study concluded that green tea consumption was associated with a decreased mortality from cardivascular disease, especially in women, but it was not associated with a decreased mortality due to cancer. Clinical trials will be needed to better define the role of green tea in our health. Meanwhile maybe I should give up my coffee in the morning for some green tea.

Reference: JAMA, 2006;296:1255-1265.

Keep It or Throw It Out?

I was cleaning out the refrigerator today in honor of September being Food Safety Education Month.

Here's a site that I found useful in this quest.

Just remember, when in doubt throw it out.


Photo: courtesy of Food Safe Schools.

Ice Cream Indulgence

Summer time and ice cream go hand in hand, but what if you need to watch the calorie intake or want to keep those coronary arteries flowing? As a self proclaimed ice cream snob I had not been able to compromise on the taste of real ice cream and settle for any of the low fat versions. And so as a physician, I have had to make that painful decision of will it be real ice cream or no ice cream. Harsh, isn't it? However, recently I discovered a happy compromise of Healthy Choice Premium Fudge Bars. Each bar has only 80 calories and 1 gram of saturated fat, and the taste is surprisingly satisfying. In comparison 1/2 cup (and who can really eat just 1/2 cup) of Haagen-Dazs coffee ice cream, my favorite splurge, has 270 calories and 11 grams of saturated fat. This may be a trade off that we can live with. In case you are wondering I have no financial or other interest in this company.

Reference: Nutrition Action, June 2006, Vol 33. Center for Science in the Public Interest.

Photo: courtesy of travelblog.org

Are Diet Sodas Safe?

A Googler asks how safe or unsafe are diet sodas?

The concern is over the artificial sweeteners in the diet drinks. There are anecdotal reports of neurological conditions such as memory loss, brain tumors, and seizures. However, I was not able to find any evidence in the medical literature that would substantiate any of these claims.

The consensus is that since obesity, diabetes, and heart disease are so prevalent in our society there is more benefit in reducing the total calorie intake by drinking diet sodas rather than regular sodas. In summary water is better than diet soda which is better than regular soda. And like every thing else moderation is key.

Is It Safe to Eat Chicken in Asia ?

A blogger asks is it safe to eat chicken in Asia.

I assume this is due to conern over bird flu.
As far as we know if the chicken is fully cooked the virus can not be transmitted.

See Bird Flu Basics.
Please note that this post of 10/05 needs to be updated to mention that due to the migration pattern of the birds the virus has appeared in European and Middle Eastern countries as you probably know by now.

Photo: courtesy of poultry.information

Life Style Changes Do Make a Difference

Just in case you were wondering if it's worth putting down the dessert and picking up the tennis shoes, here's some evidence that will hopefully motivate you to make healthier life style choices.

The data in J. A. Iestra's recent study, "Effect Size Estimates of Lifestyle and Dietary Changes on All Cause Mortality in Coronary Artery Disease Patients," shows notable reductions in coronary artery disease -- and mortality -- when patients make these changes:

Diet change: 40-45%
Smoking cessation: 35-50%
ACE inhibitors (for blood pressure): 26%
More physical activity: 20-30%
Beta blockers (for blood pressure): 23%
Statins (for cholesterol): 21%
Aspirin: 18%
Moderate alcohol: 14-20%

The reduction in mortality from coronary artery disease is the same if not better with lifestyle or dietary changes as it is with medications. Other things to consider (but not analyzed in this study) are that lifestyle changes, such as more physical activity, don't produce bad side effects -- well, maybe a little sweat, but all medications may have some side effects. And certainly the cost of exercise vs. medication is lower too. So whether you're a Googler or not, let's all be visionaries not just about our work, but about our own bodies and souls.