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Natural Ways to Increase Testosterone Bioavailability in AthletesLeave a Reply

Being a natural athlete I've always sought to find more ways to increase testosterone levels naturally. The question I've always asked myself was what are the variables, which determine how much testosterone is boiavailable.

I've read articles before, giving some advice on what in my every day life causes my test levels to go up and what causes them to go down. But after an extensive research I couldn't find an article, explaining in detail how and actually what exactly I should manipulate directly in my system to achieve the effects I desired – namely not only higher levels of circulating testosterone but also how much of it will be available to the corresponding receptors in the cell walls. Moreover, I wanted to know all this in regards to natural bodybuilding…

So, I decided to do some good digging and reading and then if I manage to put things together, to lay that in writing form so that others can benefit as well.

Without wasting even a minute more I will start this off by describing what testosterone is and what it does in the human body. Testosterone is a steroid hormone with anabolic and androgenic properties. It is the main hormone, responsible for the increase in lean muscle tissue, increased libido, energy, bone formation, and immune function.

Testosterone is secreted in the testes in men and in the ovaries in women. Small amounts are also secreted in the adrenal glands. Testosterone is derived from cholesterol. The levels of testosterone in men range between 350 and 1,000 nanograms per deciliter (ng/dl). After the age of 40 these normal levels start dropping by roughly 1 per cent a year.

In the blood stream testosterone circulates in great percentage bound to so called binding proteins. Sex Hormone Binding Globulin or SHBG is the one that concerns us the greatest. Why? Because this is the main reason why testosterone might not be available to reach the cell receptor. When testosterone gets attached to SHBG, it is no longer able to perform its anabolic functions.

What elevates SHGB: Anorexia nervosa, Hyperthyroidism, Hypogonadism (males), Androgen insensitivity/deficiency, Alcoholic hepatic cirrhosis (males), Primary biliary cirrhosis (females).

What suppresses SHGB: Obesity, Hypothyroidism, Hirsutism (females), Acne vulgaris, Polycystic ovarian disease, Acromegaly, Androgen-secreting ovarian tumors
Less than 1% of the circulating testosterone is in a free form in males (less that 3% in females). Only when in a free form this hormone can exhibit its properties by connecting to the androgen receptors on the cell walls. Based on a study 14 to 50 per cent of the testosterone is bound to SHBG in males and 37 to 75 in females. It is worth mentioning that SHGB poses very high affinity for binding to testosterone. Therefore, changes in the SHGB levels noticeably influence the level of bioavailable testosterone.

Let's discuss for a moment what exactly a testosterone bioavailability is. Other than SHGB there are two more testosterone-binding proteins, also called carriers. One of them is albumin. It is a low-affinity binding protein, thus testosterone bound to it is considered "bioavailable". Albumin binds to testosterone in the range 45 to 85 per cent in men (25 – 65 in women). The third carrier is the cortisol binding globulin, which binds also with low-affinity to less that 1 % of the testosterone in circulation.

The free androgen index (FAI) indicates the amount of bioavailable testosterone. FAI is the sum of the free testosterone and the albumin and cortisol binding globulin. Or it's the total serum testosterone minus the SHGB-bound testosterone.

It is now clear why we should focus our attention on the properties of SHGB. The levels of this binding protein increase when there is excess estrogen present. Conversely, SHGB levels drop if the testosterone levels are elevated. Here I should mention the fact that SHGB exhibits higher affinity to testosterone than to estrogen. Now, pay close attention…

It's a well-known fact that testosterone is an estrogen precursor – it will convert to estrogen under the influence of the enzyme aromatase. Nothing that we don't know so far. Here is where it gets interesting. Suppose that we have normal testosterone levels and we don't suffer from any of the health ailments, which influence the SHGB levels. That means that SHGB levels are normal, too.

Bare with me now. If more of this testosterone is converted to estrogen due to abnormal aromatase levels, the SHGB I will increase as well. SHGB, being more readily bound to testosterone, will leave us with excess estrogen levels in the system, which in turn will stimulate increased production of the SHGB protein from the liver. This whole process ultimately amplifies estrogen levels. Estrogen readily binds to the androgen receptors in cells thus leaving less opportunity for the free testosterone. Even more important, estrogen is the messenger molecule that signals the brain to decrease testosterone production.

Another thing of great importance is the fact that over 40 per cent of the SHGB protein circulates unbound in the blood stream in man (over 80 per cent in women), and albumin circulates unbound almost all of the time. Thus increase in the total testosterone levels does not produce any noticeable changes in the free testosterone levels unless there is a significant increase like the one seen after synthetic steroid hormone administration.

Well, this whole story brings us to the conclusion that the main approach should be - to keep the testosterone bioavailability high.

In this regard a natural athlete should strive to:

  • Prevent testosterone levels from getting low
  • Attempt to increase the total testosterone as a means of keeping the testosterone levels from plunging
  • Block the testosterone-binding effects of SHBG
  • Lower the levels of the enzyme aromatase - less testosterone conversion to estrogen

1. How to prevent testosterone levels from getting low?

  • Obesity. Based on the way the testosterone-estrogen mechanism works, increased levels of estrogen will ultimately decrease the circulating testosterone. Excess fat causes more estrogen production due to the fact that fat cells are those, which manufacture estrogen. So, the more fat cells, the more estrogen in the blood and the less testosterone.
  • Drug and alcohol abuse. Alcohol has the property to inhibit your ability to remove estrogen from the blood stream by acting as a central nervous system depressant and also by decreasing zinc levels.
  • Stress elevates corticosteroid levels in the blood steam, which causes the testosterone levels to decrease.
  • Medications. Some medications, including estrogen and progesterone, lower the lutenizing hormone (LH) levels. LH is the hormone, responsible for the steroid hormones production.
  • Diabetes. Studies suggest that there is a link between type 2 diabetes and lower testosterone levels.
  • Hypertension and high cholesterol levels. These both cause the arteries to harden, this way decreasing the blood flow to the sex hormone producing organs. That of course leads to low sex hormone levels.
  • Aging. Fact is after the age of 40 test levels drops by roughly one per cent per year. We can't do too much about that. The clock keeps ticking for all of us. However, we can try to manipulate testosterone levels in any other possible way.
  • Low fat diet. Low fat consumption causes increase of the SHGB, which means one thing – less free testosterone. It is considered that monounsaturated fats play an important role in testosterone levels and bioavailability.
  • Overtraining can contribute to as much as 40 per cent drop in testosterone levels. That is why it's important to notice early the signs of overtraining and give the body a week or two well-deserved rest.
  • Not enough sleep. If you are not getting enough sleep the body is not recuperating well, which causes less testosterone and more corticosteroids to be released. Just to mention corticosteroids like cortisol are in fact catabolic hormones meaning they use up muscle tissue to provide the brain and the heart with energy.
  • Vitamin C. It suppresses the release of the stress hormone cortisol. Cortisol decreases testosterone levels. So, ultimately less cortisol, more testosterone.

2. How to boost testosterone levels

  • Incorporate basic movements that involve several muscle groups in your training routine. Good ones are squats, dead lifts, and military presses. Basic (compound) exercises have been shown to play an important role in the testosterone levels.
  • The greatest workout related testosterone production occurs with the use of heavier weights and lower rep range. A study shows that the best is 85 per cent of your one-rep max.
  • Tribulus terestris is a natural supplement, which has been shown in some studies to have the ability to increase the leutenizing hormone (LH) levels. As we already mentioned above, one of the functions of LH is to stimulate testosterone production by the testes.

3. Block the testosterone-binding effects of SHBG

  • Nettle root as a highly concentrated extract has shown to be effective at binding to SHBG and therefore it permits more free testosterone to circulate the system. It also acts as a 5-alpha reductase inhibitor. This is the enzyme, responsible for the conversion of testosterone to dihydrotestosterone (DHT), a more potent form of the male sex hormone, which causes prostate enlargement and ultimately cancer. Methanolic extract of nettle can also cut down the SHBG levels, which is another form of elevating the free testosterone in the blood stream.
  • Pygeum (prunus africana) is another herb, known to block the testosterone-binding effects of SHBG. Nettle root and pygeum extracts also benefit the prostate gland as a preventive treatment for benign prostatic hyperplasia (BPH) both by blocking the 5-alpha reductase action.
  • Avena Sativa is an extract from the straw of oats. It has somewhat different properties. It works by freeing bound testosterone, which increases the free testosterone in circulation.

4. Lowering aromatize levels

  • Zinc. The mineral zinc inhibits the aromatase enzyme that converts testosterone into excess estrogen. The recommended dose for inhibiting aromatase is 80mg daily. However, be sure the combined zinc quantity of all the daily supplements you are taking does not go over this benchmark.
  • Chrysin is a bioflavonoid that has shown a potential as a natural aromatase inhibitor. Chrysin is poorly absorbed in the system. It is found that when taken along with piperine, chrysin exhibits a lot better absorption. Supplementation with chrysin and piperine together might bring good results in reducing aromatase levels.

How does this all apply in the sport of natural bodybuilding

Let's assume you are an individual, who exercises regularly and who doesn't consider taking exogenous steroid hormones. With other words you are a natural athlete or enthusiast, who desires to keep his natural testosterone levels in the range, favoring good health and lean muscle mass build up.

Here is what you do:

  1. If you are even slightly overweight consider staring immediately a diet and training routine, tailored toward fat loss and lean muscle retention.
  2. Consider also dropping the alcohol intake to absolute minimum if you want your efforts in keeping test levels high to give results.
  3. Begin mastering some types of self-control or even meditation. These will take care of the excess stress levels.
  4. Take medications only if they are absolutely essential for your health and are prescribed by your doctor. Talk to your personal physician to find out if there are any natural remedies to replace your current medications and if he recommends such approach for your health issue.
  5. Keep your blood pressure and the serum cholesterol in check.
  6. Eat enough good fats in your diet. Good means monounsaturated and omega-3 and 6 polyunsaturated fats.
  7. Don't ever overtrain. Sleep enough to promote good recovery. Signs of overtraining are loss of appetite, tiredness and irritability, lack of motivation, impaired mental focus, prolonged recovery periods.
  8. Start relying more heavily on basic exercise movements. Train in the low rep range most of the time. 5 – 8 reps will ensure that you're using weights that will eventually stimulate elevated testosterone levels.
  9. It will only do you good if you decide to try some or all of these natural supplements: chrysin - piperine blend, nettle root extract, pygeum, avena sativa extract, and tribulus terestris. Try to find them in your local health store. Follow the directions for best results.
  10. And you shouldn't even consider training without supplementing your diet with enough vitamin C (at least 1g a day) and zinc (15mg min.). Take vitamin C with your multivitamin formula after breakfast, and post-workout with your protein shake. Zinc should be present in your multivitamin blend but this is not enough. Take zinc with magnesium in the form of ZMA right before you go to bed on an empty stomach.


Ron Geraci, Men's Health, December 25, 2000; 13 Ways to Naturally Boost Your Testosterone Levels
LE Magazine January 2000; Replenish Testosterone Naturally
Plant extracts favorably alter hormone metabolism and improve sexual desire in men
Jennifer A. Kelly, Ph.D. and Leo Vankrieken, Eur. Eng. Diagnostic Products Corporation; Sex Hormone Binding Globulin and the Assessment of Androgen Status; Avena Sativa - are oats an aphrodisiac?
Gabe Mirkin, M.D.; High Cholesterol Causes Low Testosteron

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