You want as much free testosterone as you can get so there can be optimal interaction with androgen receptors for optimal anabolic activity. So after testosterone leaves the testes and enters the bloodstream (that’s total testosterone), about 44–65% of the circulating plasma T is bound strongly to sex hormone binding globulin (SHBG) and 33–54% binds loosely to albumin (that’s bio-active testosterone). So only about 2-3% of testosterone is actually free. 5% of the remaining T is then converted to DHT via the 5-reductase enzyme, and 0,2% (most people convert much more than that) is converted to estrogen via aromatase.
SHBG binds the strongest to DHT and the weakest to estrone. Highest to lowest affinity looks like this: dihydrotestosterone (DHT) > testosterone > androstenediol > estradiol > estrone. DHEA is weakly bound to SHBG as well, but DHEA-S is not. DHEA-S is the storage form of DHEA in the body.
Other steroids such as progesterone, cortisol, and corticosteroids are bound by transcortin.
SHBG isn’t useless in the body and it’s not just there to make your androgens unavailable. SHBG prevents testosterone clearance from the body, as well as prevent testosterone conversion rate to androstenedione (a weaker androgenic metabolite). SHBG also increase uptake of androgens into cells. For a more detailed article, check it out here…
Also, inflammatory cytokines like TNF-alpha and Interleukin are inversely correlated with SHBG (36). You surely don’t want to increase inflammation just for this, unless you get that inflammation from exercise in order to grow muscles.
SHBG raises as a defense mechanism in response to elevated estrogen, to help keep it under control. Once you achieve euthyroid levels, your estrogen drops, as well as SHBG.
The best way to lower SHBG would be to lower your estrogen and fix your thyroid function. Then SHBG will automatically drop and you will have more free T.
Symptoms of low free testosterone include:
- Hypogonadal symptoms even if total testosterone is normal (34)
- Elevated LH
- Low libido
- Low physical function
- Slow walk speed
- Low energy
- Less lean mass and muscle strength
- More fat mass
- Depressive mood and cognitive function (35) (the risk of developing Alzheimers’ Disease decreased 26 percent for each 10 unit increase in free testosterone index)
- Lower hematocrit
So how can we increase free testosterone?
Even though SHBG isn’t bad, free testosterone is still the fraction (and to a lesser degree albumin-bound testosterone) that binds to the androgen receptors and make the muscles anabolic.
Let’s look at a few:
Protein intake is negatively correlated with SHBG, meaning: meat eaters tend to have much lower SHBG than vegetarians. (1)
If you think that protein is bad for testosterone, you need to read this post right here. It’s very much needed to build muscle and to keep testosterone high.
2) Lower Fiber
Fiber is also a guilty contributor to SHBG levels. The more fiber you consume through your diet, the more SHBG you’ll have. (2) I have consumed a fiber-free diet for quite some time now, and I have no constipation or digestive problems.
3) Avoid Lignans
Lignans are compounds found in seeds and grains which lower the 5-alpha reductase enzyme and also increases SHBG for less free T (3).
Flax seeds are the highest source of lignans, while other grains, seeds and nuts also contain moderate to high amounts.
The only type of exercise I would recommend would be resistance training (calisthenics included), because it’s just the best kind of exercise for optimal health, muscle growth and testosterone.
An acute burst of resistance exercise increases testosterone & free testosterone quite significantly, but it doesn’t affect SHBG significantly. (4)
But all kinds of exercise is good for the body… just not as good as weight training.
45 min of bicycle spinning increases free testosterone significantly (5).
Cardio based exercises may increase free T, but it also increases SHBG a bit. Moderate to vigorous exercise of cardio for three months is shown to increase SHBG by 14.3% (6). I guess that’s still ok as you’ll still have more free T despite the higher SHBG.
I don’t really advise doing cardio based exercises just because I have done them before (for fat loss purposes only) but don’t do them anymore, as I enjoy doing weight training much more, but also do enjoy doing sprints however.
Drinking a bit of alcohol (a glass of wine) post-workout will result in significantly higher free testosterone (7). But don’t overindulge, as high alcohol consumption lowers T and significantly increases SHBG (8).
BMI has a negative correlation on SHBG. (9)
Build more muscle
A BMI over 25 is usually classified as your getting overweight.
But did you know that if you increase your muscle mass while staying lean, your BMI will also increase? So I would have to be in the fat category because my BMI is high, but I have low body fat.
Lots of muscle mass + low body fat = high BMI = lower SHBG.
If you’re unsure how to build muscle optimally, check out my products.
Lose the extra fat
But also, more fat = less SHBG, but more fat = low testosterone. So lose the fat and build muscle instead.
However, a chronic caloric deficit also increases SHBG as well as being anorexic. So just maintain good amounts of muscle and use a low carb diet to cut.
Leptin is the hormone that is released when you eat and makes you feel full.
Fasting reduces leptin, but when you eat, leptin increases as well as insulin.
Leptin reduces SHBG (11) and insulin disassociates testosterone from its binding proteins, which makes them free and increases its absorption by androgen receptors.
However, obese individuals are leptin resistant, meaning, their bodies don’t sense that they have eaten, or eaten enough, so they just continue to eat and eat…and eat.
So the best thing to do is to lose weight, become lean by eating less and only healthy (natural, organic and free range) foods which will produce leptin and insulin sensitivity.
Monosaccharides (glucose or fructose) effectively decrease SHBG expression by inducing lipogenesis, which reduces hepatic HNF-4alpha levels, a transcription factor that plays a critical role in controlling the SHBG promoter (28). Don’t worry about getting fat from carbs, as only 3-5% of carbs are converted to fat, while the rest is being burned for energy or stored as glycogen (A).
9) GI of foods
Low GI carbohydrates increase SHBG while high GI carbs actually lower it (14). It might be that low GI vegetables are high in fiber and that it causes a very low insulin release, while high GI foods are low in fiber and cause a spike in insulin.
10) Vitamin D
This sunshine vitamin increases testosterone & free testosterone. But only if you have a vitamin D deficiency. The testosterone difference is quite significant when having adequate vitamin D levels vs being deficient. Men with sufficient vitamin D levels also had significantly lower SHBG than deficient men (15, 16). So I would highly recommend getting some sunlight instead of a supplement, but if that isn’t possible, a supplement is highly valuable. More on vitamin D here…
- Vitamin D – 1000IU per serving, 180 servings
10 mg of boron supplementation results in a significant decrease in SHBG and an increase in free testosterone (17).
Boron is also a mineral, but not an essential mineral. One does consume low levels of it through your diet, but very low. For e.g. 100g of raisins contain 2.5mg of boron. But raisins are pretty high in calories, so it’s probably not the best idea to try to consume 10mg of boron from eating raisins daily.
If you plan on using boron, use 10mg, as 2.5mg of boron daily had no effect on androgens (18).
- Boron – 3mg per cap, 250 caps
Magnesium is used as a sport enhancing aid and is positively correlated with total testosterone. So magnesium is very important for a few things, such as better sleep, relaxation, lower cortisol, muscle contraction, and energy production, just to name a few.
It’s quite hard to get 100% of your DV of magnesium in through foods due to lots of anti-nutrients in foods. Leafy greens, cocoa, milk, oats, potato are a few good sources of magnesium. More on magnesium here…
- Magnesium glycinate – 200mg per serving, 113 servings
Zinc is negatively correlated with SHBG (20), and significantly positively correlated with total and free testosterone and DHT (21a, 21b, 22). Which might result in more free estrogen rather than free T.
Oysters would be the best source of zinc, 100g of oysters contain 524% of your DV of zinc. Second best is red meat 48% of your DV of zinc from just 100g.
- Zinc glycinate – 22mg per serving, 250 servings. Start with 1 serving twice daily.
Iron is also shown to be positively correlated with total testosterone and free testosterone (24).
I don’t recommend getting a supplement, and also to stay away from a supplement, as iron is highly reactive with oxygen and makes free radicals and other damage. Rather consume iron-rich foods. Vitamin C helps with iron absorption whereas vitamin E and caffeine reduce iron absorption. Vitamin E, vitamin C, melatonin protects against the toxic effect of iron.
The best source of iron would be beef liver, as 100g would give you 99% of your DV of iron.
I enjoy drinking a lot of milk. Milk is the best source of calcium, and lots of other nutrients, such as vitamin A, B2, B5, B12, D, zinc, selenium, and has a great macro-nutrient composition for testosterone production.
In this study, people who consumed the most calcium had the highest testosterone, free testosterone as well as the lowest estrogen.
The calcium from dairy products are the most bio-available, plus, milk can also increase your DHT read more here. Eggshell powder is also a great source of calcium. Just ½ a teaspoon is all you need the day.
Although forskolin is used as a fat-loss supplement, which does work, it also boosts testosterone a bit by increasing cAMP.
As seen here, individuals ingested 250mg of 10% forskolli (25mg forskolin) twice a week and increased their free testosterone by 16% after 12 weeks, while the placebo group saw no change.
This is definitely a supplement I would advise.
- Forskolin (40% extract) – 25mg forskolin per serving, 60 servings
17) Lower estrogen & increase testosterone
Estrogen significantly increases SHBG production by the liver, whereas androgens such as testosterone decrease it. Your body produces all the SHBG as a defense mechanism to deal with the high estrogen, so see it as a sign to lower estrogen, rather than SHBG. (ref)
18) Tongkat Ali
- Tongkat Ali (200:1 extract) – 100mg per serving, 60 servings. Start with 100mg twice daily. (Lost empire herbs)
- Tongkat Ali (100:1 extract) – 400mg per cap, 150 cap (South African orders only)
19) Increase DHT
20) Avoid soy
The phytoestrogen, genistein, and mitotane increase SHBG production and SHBG gene promoter activity (28).
21) Growth hormone
Continuous infusion of growth hormone is obese men reduces their SHBG, testosterone and also thyroid hormone T4, but increased T3. This shows GH is anti-metabolic and anti-androgenic (30). GH isn’t good for you, but IGF-1 is, so just focus on boosting that.
22) Lower PPARγ
PPARγ increases SHBG production (29). PPARγ promotes fat storage. The more insulin sensitive your adipose tissue is, the more fat it can uptake. Estrogen increase PPARγ expression and androgens decrease it. Polyunsaturated fats also increase PPARγ.
DHEA (dehydroepiandrosterone) lowers SHBG and increases free testosterone (30). However, under a stressful condition, is DHEA mostly aromatized. I advise to use small amounts, 5-15mg. When applied topically, more than 70% is converted to DHT. If larger doses are taken, the risk for aromatase increases.
- DHEA – 25mg per cap, 90 caps
Progesterone decreases intracellular SHBG, which might partly contribute to the abolition of the intracellular estrogen-dominant milieu, and be related to the inhibition of estrogen-dependent growth of some endometrial cancer cells (31).
- Progestene – 20mg per serving, 30 servings. Superior topical absorption
- Pregnenolone – 100mg per cap, 100 caps (also very good at boosting progesterone levels)
25) Be slightly hyperthyroidism
SHBG is elevated during hyper- and lowered during hypothyroidism (ref). Don’t try to stay close to hypo as then your androgen production suffers. Testosterone and DHT synthesis is significantly increased during hyperthyroidism (A). Although SHBG is elevated during hyperthyroidism, your free T is still significantly more elevated during hyper than hypothyroidism.
SHBG is elevated when thyroxine (thyroid hormone, T4) is elevated. T4 can be elevated due to hypothyroidism, and because due to poor liver function and slow conversion to T3, the active thyroid hormone. If this is the case, you might want to focus on fixing you liver, by eating lots of eggs for the protein and choline (which are both lipotropics). High doses of caffeine (400mg+ daily), vitamin K2 (45mg daily), glycine (1g+ daily), taurine (2g+ daily) and magnesium also helps to clean out the liver. And also, consider a selenium supplement to help convert T4 to T3.
- Caffeine – 200mg per serving, 100 servings
- Idealabs Kuinone (K2, MK-4) – 99.9% purity, 1.5mg per serving, 720 servings, superior absorption.
- Glycine – 1g per serving, 100 caps
- Taurine – 500mg per serving, 100 servings
- Magnesium glycinate – 200mg per serving, 180 servings
- Selenomethionine – 200mcg per serving, 60 servings
26) Black Musli
Black Musli, at doses of 50mg/kg significantly increased free testosterone in rats (32). The human equivalent dose would be 7.1mg/kg. So an 80kg man would have to consume 570mg daily.
27) Stinging Nettle & divanil
Stinging nettle inhibits the binding of DHT to SHBG, and the lignan, divanil ((-)-3,4-divanillyltetrahydrofuran) showed the greatest affinity (33).
- Divanil – 700mg per cap, 150 caps (South African orders only)