It should be noted that in theory if one was to consistently suppress your natural estrogen levels for a long period of time, this would negatively impact your health, including your cholesterol. Due to the ability of Letrozole- to inhibit estrogen so much, this should definitely be a concern to most users. However the research that has focused on the relationship between use of letrozole and cholesterol levels is rather inconsistent in it's findings. Many studies have concluded that the compound is detrimental to both a user's HDL and LDL cholesterol levels, while other research has found no link. Obviously individuals are best served to monitor their cholesterol while using any compound via blood tests however barring that, letrozole should simply not be run for extended periods of time if at all possible. Doing so could cause serious medical complications.
Along with the issues related to blood lipids is the fact that many users complain that their libido is dramatically reduced when using the compound. This is related to the fact that estrogen is partly responsible for the regulation of an individual's sex drive. Since Letrozole- is so potent it can often drive estrogen levels too low and this inhibits a user's libido. To avoid this users can lower dosages, but some anecdotally report that even extremely low doses of the drug can cause problems. If this is the case a less potent compound such as exemestane or anastrozole may be a more appropriate option.
Regardless of your purpose, possible side-effects may occur, but with responsible use, they are very easy to avoid. First and foremost, if you are a healthy adult male who supplements with responsible doses you will in most all cases be completely fine. To add protection, supplementing with an Aromatase Inhibitor can be extremely useful, as many of the testosterone based side-effects are aromatase based. Of course, if your dose goes to an extreme level, the higher it goes the greater the risk of adverse side-effects, and this is something you must keep in mind. If you're a healthy adult male and supplement with a dosing of 100mg every other day, you will rarely have a problem. If you are a healthy adult male looking for a really big cycle, if you supplement with 200mg every other day along with the use of an Aromatase Inhibitor such as Arimidex of Letrozole, and live a lifestyle that promotes health, you will be in the clear almost each and every time. The only reason we cannot say each and every time and must add the word "almost" is because individual genetic response is impossible to predict. For example, some people cannot take Aspirin, but most can. In any case, smaller or larger doses Aromatase Inhibitors are advised, as for with this alongside responsible use you can enjoy all the benefits of Testosterone-Propionate.
We've listed the commonly used anabolic steroids, but the next question is what the best of the best are; of the 22 forms, which ones are the best steroids of all? In many ways, this is a very hard question to answer, as your individual goals and desires will dictate quite a bit, but we will still provide some answers. Without question, if one was to be listed as the absolute best of all it would go to Trenbolone-Acetate. Any Trenbolone form will find itself at the top of the pack, but Fina simply edges out the rest, and for good reasons. There is no steroid as versatile as Trenbolone, no steroid that can provide such dramatic changes in any direction from bulking to cutting. Beyond Trenbolone, the next best steroids included the numerous testosterone forms, but if we include the importance of a steroid to the human body as well as its tolerable level testosterone wins hands down. Like Trenbolone, testosterone is very versatile, it will not provide the conditioning of Trenbolone, but it is so well-tolerated and so essential to our health it always finds itself at the top of the list. At any rate, we have again listed some steroids below, this time they have been broken down into bulking and cutting categories. We have taken the 22 most commonly used steroids, the best steroids of all and left you with the top five for bulking and the top five for cutting. Some may disagree with our choices, but each choice was made considering the hormones versatility, means to promote the specific function of the class, its milligram potency and on some level its tolerable nature. We have for your convenience also listed the best steroids for women in the final list below:
The mean oral bioavailability of finasteride is approximately 65%.  Its volume of distribution is 76 L/kg.  The plasma protein binding of finasteride is 90%.  The drug has been found to cross the blood–brain barrier , whereas levels in semen were found to be undetectable.  Finasteride is extensively metabolized in the liver , first by hydroxylation via CYP3A4 and then by aldehyde dehydrogenase .  The metabolites of finasteride have about 20% of its potency in inhibiting 5α-reductase and hence its metabolites are not particularly active.  The drug has a terminal half-life of 5 to 6 hours in adult men (18–60 years of age) and a terminal half-life of 8 hours or more in elderly men (greater than 70 years of age).  It is eliminated as its metabolites 57% in the feces and 40% in the urine . 
Stanozolol oral intake in the form initially absorbed in the digestive tract, and later transferred to the liver, the presumption is that the blood stream reaches the much less active substance than the injectable form. Studies have shown that oral administration of stanozolol is metabolized in the body two times, where there's injectable only once, so the effects of injection Winstrolu are much higher, especially in terms of increasing protein synthesis.
Another interesting fact is that oral administration of stanozolol, at a dose mg / kg body weight decreases SHBG by 50%. What course reinforces anabolic effect cures. But the point is that the injectable stanozolol SHBG decreases at the same dose of only 11%.
Much of the free TST is bound to SHBG, thus reducing the anabolic effect of TST, thanks stanozolol you can reduce SHBG, thus ensuring better efficiency of the TST. It is therefore recommended after 5 weeks of treatment taking stanozolol in cure because it increases anablic effect.
The mean oral bioavailability of finasteride is approximately 65%.  Its volume of distribution is 76 L/kg.  The plasma protein binding of finasteride is 90%.  The drug has been found to cross the blood–brain barrier , whereas levels in semen were found to be undetectable.  Finasteride is extensively metabolized in the liver , first by hydroxylation via CYP3A4 and then by aldehyde dehydrogenase .  The metabolites of finasteride have about 20% of its potency in inhibiting 5α-reductase and hence its metabolites are not particularly active.  The drug has a terminal half-life of 5 to 6 hours in adult men (18–60 years of age) and a terminal half-life of 8 hours or more in elderly men (greater than 70 years of age).  It is eliminated as its metabolites 57% in the feces and 40% in the urine .