So, nandrolone may be a little less safe than testosterone in regard to lipids, perhaps owing to its lower affinity for aromatization to estrogen. Primobolan Depot (methenolone enanthate) has seen much less study in Western medicine, although it's expected to have an even worse effect on lipids, owing to the fact that it's a non-aromatizable anabolic steroid. It too is commonly identified as the safest steroid, but indeed I would place it slightly behind Deca Durabolin in relative cardiovascular risk. Honestly, all three of these hormones are relatively safe when used in reasonable doses for limited periods of time. But you asked for the absolute safest, and in that regard, I'd say any slow-acting ester of testosterone would fit the bill, including cypionate, enanthate, or Sustanon 100/250. These drugs also have the benefit of not being weak muscle builders and in fact work extremely well for that purpose.