quoted from "anabolics 9th edition" on tamoxifen citrate (nolvadex):
Note that like some other triphenylethylene compounds, tamoxifen citrate can act as an estrogen in the liver.
Estrogenic action in the liver is important in the regulation of serum cholesterol, and tends to support HDL (good) cholesterol synthesis and LDL (bad) cholesterol reductions.
Since steroid-using bodybuilders are already dealing with the negative cardiovascular effects of these drugs, compounding the issue with aromatase inhibitors (which will lower total serum estrogen levels) may not always be the best option. Using a drug that blocks gynecomastia, for example, while at the same time supporting improved cholesterol values, might be much more ideal.
It is important to note that tamoxifen citrate is not sufficient to stabilize serum cholesterol at healthy levels with the use of c-17alpha alkylated orals or high doses of steroids in general. The effect it would have on cholesterol values would likely be one of degrees, and cannot be relied upon to eliminate cardiovascular disease risk from anabolic/androgenic steroid use.