By Larry Altshuler, M.D.

Published in Radius Magazine, Spring 2011

      Fish oil has quickly become one of the most common supplements purchased by consumers and for good reason. Research studies have shown it to be beneficial for numerous conditions (See Table 1), especially related to the heart (Table 2).

TABLE 1
 SOME CONDITIONS BENEFITED BY FISH OIL

                                                     Age-related eye problems Asthma in children
                                                     Bipolar disorder (depressive type) ADHD
                                                     Cachexia in cancer Depression
                                                     Diabetic kidney disease Painful menstrual periods
                                                     High cholesterol High Blood Pressure
                                                     High triglycerides Obesity (Helps lose weight)
                                                     Osteoporosis Rheumatoid arthritis
                                                     Reduces risk of stroke

Despite its benefits, there are problems with fish oils of which you need to be aware. It is not just a matter of going into a store and buying what’s on the shelf. You may not be getting what you think you are.

Omega fatty acids: It Can Be Confusing

The key ingredients of fish oil are called omega-3 fatty acids (called omega-3’s for short). However, you should realize that there are several types of omega-3’s, and there are also other fatty acids, such as omega-6’s, all of which can have some benefits and are commonly purchased by consumers. What to take can be confusing, so let me clarify.

First, there are two main omega-3’s in fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Another omega-3 is alpha-linoleic acid, which is found primarily in plant oils, such as flaxseed. What you need to know is that omega-3’s from fish oil are much more potent than omega-3’s from plants.

Second, omega-6 fatty acids, found in evening primrose oil and borage oil, are often taken by consumers along with omega-3’s. What you need to know is that omega-6’s and omega-3’s compete with each other for binding sites in the body. Taking fish oil with these herbs, or combination products with both omega-3’s and omega-6’s, can often negate each others’ effects, so you should avoid taking them together.

How Much Is Enough?

A major problem consumers have is to know how much fish oil is needed to obtain the maximum benefits. Many manufacturers recommend taking 1000 mg (1 gram) total of DHA plus EPA daily, but all studies showing the benefits of fish oil utilize 3-4 grams per day. So, if you are only taking one capsule a day of regular fish oil (which usually equates to one gram or less), you will obtain some benefit, but not the maximum.

Side Effects of Fish Oil: What Is Too Much?

Taking too little is one problem, but taking too much is another. If you take the recommended 3-4 grams per day, side effects are uncommon. Even so, you still may have a fishy aftertaste or “fish burp”, halitosis, heartburn, nausea, loose stools or rash. However, you can decrease these side effects by taking the fish oil with meals or freezing them.

More serious, doses greater than 3-4 grams can increase the risk of bleeding, especially if you take blood thinners or aspirin. Some fish oil preparations (like cod liver oil) contain large amounts of vitamin A and vitamin D, which can cause toxicities if taken in large amounts or for a long time. Large doses can also adversely affect immune function and can increase LDL cholesterol (the “bad” cholesterol) in some people. This latter effect can be negated by taking garlic supplements.

The bottom line is that taking 3-4 grams per day will provide you the maximum benefits: Taking more than that will not provide any additional benefit but may cause serious side effects.

Buying Fish Oil: Beware The Pitfalls

Most consumers do not realize that most fish oils deteriorate rapidly, usually within three months. The problem is that fish oil is so unstable, it begins to oxidize as soon as it is extracted from fish and exposed to air, which is usually long before it is placed into a capsule. The more it is oxidized, the less effective it becomes. If the fish oil you buy has been on the shelf for a while, it may have already lost its potency. If you buy large quantities of fish oil capsules, the benefits will quickly diminish and may even disappear before you finish the bottle.

There are numerous fish oils on the market and it is difficult to know which one to buy. As a general rule, you get what you pay for: the cheaper fish oils usually deteriorate quicker and are not as high quality. However, some over-the-counter fish oils can be just as beneficial as more expensive fish oils sold by pharmaceutical companies. You may also pay more if the fish oil is combined with other vitamins and minerals (See Table 3).

One fish oil that may be advantageous is Krill oil. This oil is more expensive than other regular fish oils but has the advantage of being shelf stable for two years. It also contains the natural antioxidants vitamins E and A, astaxanthin and canthaxanthin. In addition, 500 mg of Krill oil is equivalent to 2 grams of regular fish oil in its effects, so you can take one or two capsule rather than three or four.

Should You Take Fish Oil?

So, who should take fish oil? You should definitely take it if you have heart disease or even a high risk for heart disease. You should take it if you have one of the medical conditions in Tables 1 or 2. Overall, however, it has benefits for most people, even if healthy, and can even be taken by children.