For people who are unable to eat enough fish to reap the health benefits, taking fish oil supplements is the next best thing. You probably expect the only ingredients to be the omega-3 fats EPA and DHA, so it may surprise you to see a few other ingredients such as soy listed on the label. Unless you have a soy sensitivity or must avoid soy for another reason, this is no cause for alarm.
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Concerns About Soy in Fish Oil
Because soy contains plant estrogens that weakly mimic the hormone estrogen, you may have concerns about its use as an additive in fish oil. Phytoestrogens are not known to be harmful to humans, according to the book "Encyclopedia of Dietary Supplements," compiled by the National Institutes of Health. Regardless, it may ease your concerns to know that fish oil does not contain the phytoestrogen fraction of soy. On the other hand, some people are looking to avoid soy because it's a leading GMO crop. If this is the case, simply choose an organic fish oil which will contain non-GMO ingredients.
You're likely wondering why soy is found in commercial fish oil supplements in the first place. It's actually the lecithin fraction that is extracted and used as an additive to fish oil due to its emulsifying abilities. The addition of lecithin helps keep fish oil from oxidizing -- going bad when exposed to air. If you have a soy allergy, know that most of the protein -- the allergen -- is removed from soy lecithin. It may contain trace amounts, so it's best to avoid it if you're extremely sensitive.
Source of Vitamin E
Another reason soy is often found in the ingredient list of fish oil is that it's used as a source of vitamin E. This requires the manufacturer to use a "contains soy or soy ingredients" warning. Vitamin E is a fat-soluble antioxidant. Taking fish oil increases the body's requirement for vitamin E. Because of this, some manufacturers extract vitamin E from soybean oil, an inexpensive source. The added vitamin E helps balance the increased need for vitamin E when supplementing fish oil.
How to Avoid Soy
Some people must avoid soy due to very sensitive allergies, while others choose to avoid soy because, for example, it interferes with certain medications. Soy-free fish oil supplements are available, although it takes some careful searching to find one. Look for "soy-free" or "no soy" on the label, or check under the allergens section of the label to see if soy is listed. If it's not, check the ingredients section for soy.