The DHT derivative AASs lower HDL levels causing a bad HDL/LDL ratio. i'm not sure the exact mechanism is known for sure, but has something to do with HDL production in the liver. They do know that high dose niacin increases HDL production in the liver, but even that exact process is still unknown. Unfortunately adding niacin is not enough to offset the effect of DHT derivatives and can cause liver damage if used at the same time. This is another reason why you MUST cycle your substances with AT LEAST as much time off as on and have a lipid panel done along with all the other blood work when on cycle.