According to the results of a recent clinical trial, fish oil pills and B vitamins are not helpful in helping heart and stroke patients fight the symptoms of depression. In fact, it turns out that when men were given fish oil, they actually seemed to experience even more depression.

The researchers are careful to say that they can’t confirm the fish oil is the reason for the depression; however, they also state that there is no proof that the fish oil or vitamin B helps prevent depression, either. For this reason, it is not really clear if heart disease patients should use the supplements on a regular basis.

“Generally, it should be stressed that the dietary supplements that we studied are in fact active substances that, when taken over a long period and without a physician’s advice, might not have positive effects on health,” lead researcher Valentina A. Andreeva of the University of Paris said in an email.

She also added that using supplements long-term may actually be harmful for some people. Some studies have discovered that depressed patients who have suffered from a heart attack or stroke are likely to do worse than those who are not depressed, but they don’t know why that is. Fish oil looked to be a good combatant due to the fact that it’s rich in omega-3 fatty acids, which are generally believed to be good the heart. Of course, this study, which was reported in the American Journal of Clinical Nutrition, found that the fish oil really didn’t do anything.

Even vitamin B was thought to be of use to depressed heart patients because it is thought to be a mood regulator. Prescription medications like the SSRIs Paxil and Effexor also affect the brain’s serotonin levels and are often used to treat depression. The problem with using drugs like Paxil or Effexor is that those drugs are also linked to serious adverse side effects, including aggressive and suicidal thoughts and behavior and birth defects in babies whose mothers take the drugs while pregnant. It is likely those side effects that made the fish oil and vitamin B seem like such a good idea in the first place. Unfortunately, it looks like researchers will have to find something else in treating depressed heart patients.