Sex Hormone Binding Globulin – Part 2
In my previous article, I detailed what Sex Hormone Binding Globulin (SHBG) is, the old theory about it being strictly a bad thing, and how new science shows that this is not the case. If you missed that you can find it here.
In this article, we’ll dive into more detail about various interventions that have been shown to increase or decrease SHBG.
Most of the following information comes from an extremely comprehensive article on SelfHacked.com.
This article links to primary research on everything listed there, so I figured I didn’t need to re-do their amazing work. I summarize their findings below for easy of use and say click over there if you want the deeper details.
Causes of Low SHBG Levels
• High Insulin Levels
• High Growth Hormone Levels
• High Prolactin Levels
• High Testosterone Levels
• Non-Alcoholic Fatty Liver Disease
• Certain Genetic Mutations
• High Sugar Diet
• Steroid Use
• Possibly Low Thyroid Hormone Levels (research is mixed)
• Possibly High Growth Factor Levels (research is mixed)
Although these are listed as causes, I think it is important to look at with the hormones that you can get caught up in vicious or virtuous cycles. High testosterone tends to keep SHBG low…but also vice versa.
Diseases or Conditions Correlated with Low SHBG Levels
• Type 2 Diabetes
• Gestational Diabetes
• Metabolic Syndrome
• Breast Cancer
• Heart Disease
• High Blood Pressure
• High Cortisol
• Congenital Adrenal Hyperplasia
Did you notice inflammation being linked up above in the first list? That is at the root of almost everything listed here. Very important to note.
How to Increase SHBG Levels
• Low fat, high fiber diet
• Calorie restricted diet
• Vegetarian or vegan diet
• Olive oil
• Other Caffeinated Drinks
• Cruciferous Vegetables
• Aerobic Exercise
• Strength Training
• Weight Loss
Here is where we start to get to some interesting things. A few different diets have been shown to increase SHBG. These include low-fat varieties, calorie restriction of any kind, as well as vegetarian or vegan diets.
And specifically, we see a number of specific foods and drinks that increase SHBG.
Lastly, it appears that ANY and ALL forms of exercise will increase SHBG. InsideTracker stated this in one of their articles, read more here.
“Both intense resistance and endurance-type exercise increase SHBG production. Interestingly, in resistance exercise, despite potentially decreasing free testosterone levels, SHBG correlates with increased hypertrophy and muscle strength, though now that we know that specific SHBG receptors do exist (i.e. RSHBG and megalin), this result is not as surprising.”
Let me reiterate that point because I find it important personally. “SHBG correlates with increased hypertrophy and muscle strength.” Obviously, I’m not a super muscular guy, but I do focus on strength, i.e. what I can do not what I look like. Unfortunately, I’m not willing to stop training for a period of weeks just to see if my SHBG goes down.
There is likely some mechanism at play in how hormones may be transported and used in muscles doing the work, which then upregulates the need for SHBG. (It makes me wonder if my high SHBG is because of the crazy strength work I do?)
That lends credence to the idea that high SHBG could be because of systemic inflammation and other ill-health, and it could also be because of exercising a lot. The reason why it’s high is likely critical.
Causes of High SHBG
• High Estrogen Levels
• High Thyroid Hormone (T4 and T3) Levels
• Low Growth Hormone Levels
• Liver Issues and Disorders (Cirrhosis, Hepatitis)
• High Iron Levels
• Alcohol Consumption
• Drugs (including Oral Contraceptives, Aromatase Blockers, Anti-Seizure Medication,
Selective Estrogen Receptor Modulators, Metformin, and some Antipsychotics)
Now we flip from low SHBG to high and we see many opposites involved. Here there appear to be a few hormones that interact with SHBG in the opposite way. Once again, all hormones operate off of feedback loops.
In addition, there are a number of unhealthy behaviors and conditions that can easily be seen here.
Diseases or Conditions Correlated with High SHBG Levels
• Bone Loss
• Alzheimer’s Disease
• Possibly Prostate Cancer (research is mixed, though meta-analysis points to there not being a link)
Very interesting that this is a much smaller list. Only two items if we throw out the third which looks like it is safe to do.
As for bone loss that may only be an issue with other hormones, low estrogen and testosterone, and not because of SHBG by itself.
Unfortunately, how SHBG is linked to Alzheimer’s is unclear.
How to Lower SHBG Levels
• High Protein Diet
• High Fat Diet
• Low Fiber Diet
• Red Wine
• Vitamin D
• Fish Oil
• Drugs (Glucocorticoids including Prednisone, Prednisolone, Dexamethasone)
Here, the opposite dietary approaches work as compared to raising SHBG. Specifically, we see a number of nutrients are key. These same nutrients are necessary for good hormone health and just good health period, so make sure you get them.
Finally…Herbs that Lower SHBG
Tongkat Ali has been shown to reduce SHBG in one pilot study, which in turn increased free testosterone. 
An in vitro study found that Nettle Root lignans were found to bind to SHBG, most notably (-)-3,4-divanillyltetrahydrofuran. 
This binding with the lignans, in turn, appears to reduce the binding activity of SHBG. 
Another study found that a water extract of Nettle Root, but not alcohol extract, nor isolated compounds of U. dioica agglutinin or stigmasta-4-en-3-one, modulated the binding of SHBG on receptors on human prostate membranes. 
Maca was not shown to change SHBG status in 29 postmenopausal Chinese women. 
There’s a reputation for oats helping to increase testosterone, possibly by the avenacosides binding to SHBG. However, I cannot locate this research, the only thing I found was saying it was an unpublished study. Fenugreek extract was shown to lower SHBG in a double-blind place controlled study of 80 women from 20 to 49 years old. 
Why is My SHBG so High?
Honestly, I wrote this article to better answer this question for myself. And of course, I knew it would help other people interested in the same thing.
My SHBG is always high. But I noticed that the InsideTracker reference range only goes up to 50 nmol/L. Other reference ranges go up to 60.
I’d still be high with my last test of 88, but some of my earlier tests would have been in range.
But looking at everything listed here why is it high?
1. Genetics (not proven but a guess)
2. Intense exercise regularly
3. Higher fat and protein diet
4. Regular consumption of olive oil, nuts, coffee, tea, and cruciferous vegetables
5. Semi-regular alcoholic consumption (speaking of this, I think I was drinking a bit more than usual before the last test)
6. Iron levels are usually high too
The things I’ve done that should lower it include getting good amounts of the micronutrients listed, though some of those haven’t been tested and verified lately.
In my last testing product, I was taking more Nettle Root than before, both the powder and the tincture. My SHBG was not any lower, in fact,I had the biggest amount in a while. (Well, it is possible it would have been higher without it. Impossible to say for sure.)
Maybe next time I’ll work with Tongkat Ali to see if that lowers my SHBG. I have not really used fenugreek so I can’t comment on that one.
Higher is Better?
Contrary to the overly-simplified picture of SHBG as bad, there is evidence that higher amounts might be beneficial.
“Higher testosterone and SHBG levels in aging males are independently associated with higher insulin sensitivity and a reduced risk of the metabolic syndrome, independent of insulin levels and body composition measurements, suggesting that these hormones may protect against the development of the metabolic syndrome.”
One question that this leads me to ask is this. Is it best to have high SHBG as long as free testosterone is still high? Does it depend on WHY it is high in the first place?
But then there was that link to Alzheimer’s. Is SHBG active inside the brain? It seems so since some are produced locally there. What’s its role there?
I’m sure this two-part article has raised more questions than it answered. But any investigation ought to.
To sum up, SHBG is not the hormone boogeyman it was originally made out to be. With so many questions unanswered it is likely best to focus on other areas and root causes rather than specifically trying to change this number.
Got comments or questions? Want to share what has worked for you, or not, in regards to SHBG? Post below…
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2. Henkel RR, Wang R, et al. Tongkat Ali as a potential herbal supplement for physically active male and female seniors–a pilot study. Phytother Res. 2014 Apr;28(4):544-50. doi: 10.1002/ptr.5017. Epub 2013 Jun 11. https://www.ncbi.nlm.nih.gov/pubmed/23754792
3. Schöttner M1, Gansser D, Spiteller G. Lignans from the roots of Urtica dioica and their metabolites bind to human sex hormone-binding globulin (SHBG). Planta Med. 1997 Dec;63(6):529-32. https://www.ncbi.nlm.nih.gov/pubmed/?term=Lignans+from+the+roots+of+Urtica+dioica+and+their+metabolites+bind+to+human+sex+hormone+binding+globulin+(SHBG)
4. Gansser D, Spiteller G. Plant constituents interfering with human sex hormone-binding globulin. Evaluation of a test method and its application to Urtica dioica root extracts. Z Naturforsch C. 1995 Jan-Feb;50(1-2):98-104. https://www.ncbi.nlm.nih.gov/pubmed/7702715
5. Hryb DJ, Khan MS, Romas NA, Rosner W. The effect of extracts of the roots of the stinging nettle (Urtica dioica) on the interaction of SHBG with its receptor on human prostatic membranes. Planta Med. 1995 Feb;61(1):31-2. https://www.ncbi.nlm.nih.gov/pubmed/7700987
6. Stojanovska L, Law C, Lai B, et al. Maca reduces blood pressure and depression, in a pilot study in postmenopausal women. Climacteric. 2015 Feb;18(1):69-78. https://www.ncbi.nlm.nih.gov/pubmed/24931003
7. Rao A., Steel E., et al. Influence of a Specialized Trigonella foenum-graecum Seed Extract (Libifem), on Testosterone, Estradiol and Sexual Function in Healthy Menstruating Women, a Randomised Placebo-Controlled Study. Phytother Res. 2015 Aug;29(8):1123-30. https://www.ncbi.nlm.nih.gov/pubmed/25914334
8. Muller M, Grobbee DE, den Tonkelaar I, Lamberts SW, van der Schouw YT. Endogenous sex hormones and metabolic syndrome in aging men. J Clin Endocrinol Metab. 2005 May; 90(5):2618-23. https://www.ncbi.nlm.nih.gov/pubmed/15687322/