Google fish oil and dozens of websites pop up, many of them boasting claims about how the supplement can improve your health and even stave off disease.

What makes fish oil so special? Well, fish and fish oil are packed with two omega-3 fatty acids commonly known as DHA and EPA. These fatty acids are necessary for overall health, but when it comes to thwarting diseases, what can a fish oil supplement really do?

Numerous studies have shown that taking fish oil or eating fish like salmon or tuna can boost your heart health and possibly prevent heart attacks from recurring. Research has even shown that people who eat fish regularly are less likely to die from heart disease than people who don’t.

But if you are taking fish oil to stave off dementia or supercharge your brain power in old age, you may not get the results you’re looking for.

Although some research has linked eating more fish to a lessened risk of developing dementia, a new British study found no connection between taking fish oil and better cognitive function in older adults over a two-year period. Of course, that doesn’t mean fish oil won’t keep your brain in shape, it just might take longer than two years to do it.

Studies have also been done examining fish oil’s potential effects on several conditions such as diabetes, arthritis, cancer, depression and asthma. Researchers have found no benefits linked to diabetes and for most other conditions, the results conflict from study to study.

Your doctor may still recommend taking a supplement like fish oil, though. And nutritionists recommend eating fish as part of a healthy diet. After all, fish oil may not cure all that ails you, but taking it could still give your body a boost of healthy omega-3s.