Vegans who don't eat meat or fish may have low levels of important fatty acids in their bodies. A study gave some vegans supplements of different fatty acids to see if it would increase these levels. The supplements didn't make a big difference in the fatty acid levels, except when two types were given together. Even then, the increase was small. This suggests that the body may not easily convert one type of fatty acid into another. It also shows that having a lot of one type of fatty acid in the diet may not necessarily lead to higher levels in the body.