In what ways does niacin help our body?

Niacin. Supplementing with 2000-3000mg of flush free Niacin daily can help to control your cholesterol levels quite nicely, even increasing your HDL and converting your LDL to a less harmful subtype. As a negative, Niacin can cause facial flushing and redness so get the flush free variety. And have your liver enzyme values monitored, as they can be affected by Niacin use.
Cholesterol... Niacin helps the cholesterol profile in three ways. It lowers triglycerides, raises the good cholesterol, hdl, and makes the small, dense LDL particles more large and buoyant, thereby less likely to get into a plaque. Downside: "flushing" of the body and it makes your body more Insulin resistant.