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Mayo Clinic Q&A: It’s not all in the genes; omega-3 fatty acids for dry eye

Published: October 24, 2017 Updated: October 26, 2017 at 01:09 PM
iStockphoto Pills in hands. Fish oil.


How big of a role does genetics play in weight? If you are predisposed to obesity because of your genes, how effective can a diet or other weight-loss strategies really be in the long run?

Genetics play a role in determining your weight, but thatís not the whole story. Environment, lifestyle and healthy choices still contribute a great deal to how much you weigh. And your genes also make a difference in the type of weight-loss strategies that may work best for you. When deciding how to move forward with achieving weight loss, all of these factors must be considered.

Obesity is a significant concern in the United States. According to the Centers for Disease Control and Prevention, two-thirds of Americans are overweight and one-third of people in this country are obese. Thatís a problem, because obesity is associated with many serious health concerns, including diabetes, heart disease and stroke. The CDC also estimates that the annual medical cost of obesity in the United States is about $150 billion per year.

With two-thirds of the U.S. population overweight, itís clear that a better way to manage weight is needed. Rather than approaching weight loss as if everyone has the same problem, a more individualized strategy is needed.

Genetic analysis can be useful for creating an individual approach to weight loss. For example, your genetics can make a difference in factors such as how full you feel as you eat, your appetite levels and how your body uses energy and burns calories. All of those ó energy expenditure, level of fullness, appetite, body composition and gastric emptying ó can be measured and evaluated. Specific types of testing also can reveal how your body responds to certain medications.

That information can be very valuable in crafting a weight-loss program that fits your bodyís needs and make it more likely that you will be able to lose weight and keep it off over the long term.

An example of how this type of careful evaluation can make a difference can be seen in the use of weight-loss medication. Currently, the U.S. Food and Drug Administration has approved five medications for weight loss in people who are obese. Usually, when these medications are used, about 30 percent of people will not respond, seeing little or no effect on weight loss due to the medication. About 30 percent will respond in a modest way. And about 30 percent will have a significant weight-loss response ó equaling a loss of more than 10 percent of total body weight in a year.

Recent studies show that, depending in part on an individualís makeup, health care providers may someday be able to use specific testing and genetic analysis to select the right medication for the right patient. In the future, genetics also may help to show how effective weight-loss procedures, such as gastric bypass surgery, might be for an individual.

It is important to note, however, that medical treatment for weight loss, such as medication and surgery, must be accompanied by lifestyle changes that include a healthy diet and regular exercise. Without dedicated attention and effort put into those areas, no weight-loss intervention can succeed over time.

Andres Acosta, M.D., Ph.D., Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minn.e_SClBOMEGA-3 FATTY ACIDS APPEAR TO EASE DRY EYE SYMPTOMS

Is it true that fish oil or an omega-3 supplement can help people with dry eyes? If I decide to take them, do omega-3 supplements have any side effects I should worry about?

Research suggests that taking an omega-3 fatty acid supplement can reduce symptoms of dry eyes. Omega-3 supplements are safe for most healthy adults and generally have few side effects when taken in a standard dose. Before you begin taking a supplement, however, talk with your health care provider to make sure itís right for you.

To maintain eye comfort and good vision, the front surface of your eye must be covered with an even layer of tears that contain the right mix of water and oils. If tears are not of sufficient quantity or quality to maintain that layer, dry eye disease (also called ocular surface disease) can develop.

Symptoms of dry eyes can be bothersome and may include a stinging, itchy or burning sensation in your eye; sensitivity to light; blurred vision; mucus in or around your eye; and excessive tearing. Dry eye disease tends to be a chronic condition, and it usually cannot be cured completely. However, various treatments can be used to ease symptoms, including over-the-counter artificial tear eye drops.

In recent years, fish oil has been suggested as a possible remedy for dry eyes. Fish oil contains two omega-3 fatty acids called docosahexaenoic acid, or DHA, and eicosapentaenoic acid, or EPA. Omega-3 fatty acids are thought to provide a wide range of health benefits. Due to these potential benefits, fish oil has become a popular dietary supplement.

Research studies looking into the benefits of omega-3 fatty acid supplements have found fewer dry eye symptoms in people who take the supplement. It appears that omega-3 fatty acids can improve the eyeís oil film thatís produced by small glands on the edge of the eyelid, called the meibomian glands. That improves dry eye symptoms and reduces the need for artificial tears.

The dose of omega-3 fatty acid in many of the research studies included 180 milligrams of eicosapentaenoic acid and 120 milligrams of docosahexaenoic acid, taken twice a day. Few side effects were noted at this level. High doses of the supplement have been associated with some have harmful effects, though. They include an increased bleeding risk, higher levels of low-density lipoprotein (LDL, or "bad") cholesterol, blood sugar control problems and a fishy aftertaste or odor. In some at-risk populations, such as people who have had a heart transplant, omega-3 fatty acids may affect heart rate. If you have heart disease, only take omega-3 fatty acids under the direction of a health care provider.

You can get fish oil in your diet from eating fish, too, of course. The American Heart Association recommends that healthy adults eat fish at least twice a week. Fatty fish, such as catfish, halibut, salmon, striped sea bass and albacore tuna, are good sources of omega-3 fatty acids.

Some fish can contain high levels of mercury. While the mercury in fish doesnít lead to problems in most healthy adults, it can be a concern for women who are pregnant or planning to become pregnant. If thatís the case for you, ask your health care provider about the right amount of fish in your diet and the types of fish that are safest to eat.

If you decide to take an omega-3 fatty acid supplement, talk to your health care provider first. He or she can review your medical history to ensure itís appropriate for you and help you determine the right dose for your situation.

Katherine Zeratsky, R.D., Endocrinology and Nutrition, Mayo Clinic, Rochester, Minn.e_SClBMayo Clinic Q & A is an educational resource and doesnít replace regular medical care. Email a question to [email protected] For more information, visit © 2017 Mayo Foundation for Medical Education and Research. Distributed by Tribune Content Agency, LLC. All rights reserved.