Fish oil capsules can be beneficial nutritional supplements when used correctly. However, too much of this good thing can prove to be counterproductive. The U.S. Food and Drug Administration has established the safe level of fish oil consumption at no more than three grams per day. When consumed in excess, negative side effects of fish oil capsules can include a heightened risk of vitamin D toxicity and vitamin A toxicity, interference in blood clotting, and an increase in bad cholesterol levels.
The primary benefits of fish oil capsules are vitamin D and omega-3 fatty acids. Vitamin D plays a role in bone health, regulating blood pressure, and various immune functions. It can also help to reduce the risk of diabetes and certain types of cancer. According to the University of Maryland Medical Center, omega-3 fatty acids are involved in brain function and body development. As reported by the UK National Health Service, a study by the University of California links omega-3 fatty acids from fish to improved heart health.
However, when taken in excess there can also be negative side effects of fish oil capsules. According to the Creighton University Medical Center, many of these are simply minor annoyances. Minor negative side-effects of fish oil capsules include fishy-smelling breath and bodily excretions, upset stomach or bloating, nausea, and diarrhea.
Creighton University reports that fish oil can have a blood thinning effect, interfering with the ability for blood to clot. As a result, a possible negative side effects of fish oil capsules is nose bleeding. The body can also become more susceptible to bruising.
High levels of fish oil can actually interfere with the absorption of other essential nutrients including vitamin A and vitamin E. According to the Mayo Clinic, this negative side effect of fish oil capsules is cumulative from extended use over a period of months. Absorbing fish oil uses vitamin E, so the body’s requirement for the vitamin is greater when taking fish oil capsules.
Opposed to a deficiency, fish liver oil can actually cause levels of vitamins A and D to become too high, eventually leading to toxicity, per the Mayo Clinic. When the body experiences vitamin D toxicity, side effects can include reduced bone strength and an increased risk of kidney stones. In vitamin A toxicity, symptoms include dry skin, appetite loss, and achiness throughout the body. This only applies to fish liver oil as it contains vitamins A and D.
High doses or extended use of fish oil capsules may increase the LDL or bad cholesterol levels in the body. The Mayo Clinic reports that the increase is generally between five and ten percent and depend upon how much is taken.
Negative side effects of fish oil capsules do not develop in everyone and they will generally only show up in high doses or with extended use. The best way to realize the benefits of fish oil is to eat seafood. The body absorbs nutrients from food more effectively than it does from supplements. The American Heart Association recommends eating at least two servings of fish per week to get plenty of omega-3 fatty acids.