Inhibit aromatase naturally

How to Inhibit Aromatase Without Inhibiting 5 Alpha Reductase

In Dihydrotestosterone, Estrogen by Marcel8 Comments

Aromatase and 5 alpha reductase are two enzymes under the same transmission and switch gears as one. When one is stimulated the other gets triggered. When you inhibit aromatase 5 alpha reductase gets inhibited as well to some degree and vice versa.

Aromatase aka estrogen synthase is an enzyme responsible for a key step in the biosynthesis of estrogens. Aromatase is responsible for the aromatization of androgens into estrogens.

5 alpha reductase are enzymes involved in steroid metabolism. They participate in 3 metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. 5 alpha reductase converts testosterone into the more potent DHT. There are 5 isoenzymes of 5-alpha reductase – 5α-R1, 5α-R2, 5α-R3, GPSN2 and GPSN2L proteins.

Typical aromatase inhibiting and estrogen lowering foods and compounds inhibit 5 alpha to some degree and this leaves you with less estrogen, less DHT, and more total testosterone. The hormonal manipulation there is simply less estrogen and DHT and more total testosterone.

Take a look at some typical aromatase inhibiting and estrogen lowering foods and compounds:

DIM (found in cruciferous vegetables) – DIM lowers estrogen by converting it into less potent forms (study). Then DIM inhibits 5 alpha as well (study).

Calcium-d-glucarate (found in berries) – Calcium-d-glucarate lowers estrogen (study), but then it lowers DHT as well (study).

Quercetin (found in onions and garlic) – Quercetin inhibits aromatase (study), but then again it inhibits 5 alpha as well (study).

Now you’re probably thinking of how to inhibit aromatase without inhibiting 5 alpha as well so you can lower your estrogen without lowering DHT and indirectly increase DHT.

5 Ways to Inhibit Aromatase Without Inhibiting 5 Alpha Reductase

  1. Coffee
  2. Nicotine
  3. Vitamin E
  4. Moderate dose zinc
  5. Niacinamide


Coffee is one of the greatest beverages a man can drink. Increases testosterone, DHT, dopamine, and some more androgens. Another upside to coffee – it can inhibit aromatase and not just without inhibiting 5 alpha, but increase testosterone and DHT as well.

This study here found out that coffee consumption decreases the risk of breast cancer in premenopausal women. A common cause of breast cancer is high estrogen so the decreased risk of it is probably because coffee decreases estrogen.

“Consumption of regular coffee was associated with linear declines in breast cancer risk. Consumers of ≥4 cups/d experienced a 40% risk reduction.”

Then this study says coffee is a strong aromatase inhibitor.

“Another study reported results in units/100 g wet weight (one unit was defined as the dose required for 50% inhibition) and found tea (C. sinensis), coffee (Coffea L. sp.), cocoa (Theobroma cacao L.), collards (Brassica oleracea L.), and tomato leaves (Lycopersicon esculentum Mill.) to strongly inhibit aromatase.”

An experiment here found out that coffee is associated with lower total and free estradiol.

“Coffee intake was significantly associated with lower luteal total and free estradiol levels, but not luteal progesterone levels.”

Coffee lowers estrogen and increases androgens. Win win.

“Caffeine intake increased the concentrations of T and DHT, organ weight, epithelial cell proliferation and androgen receptor tissue expression in the ventral prostatic lobe.”

“Chronic caffeine intake from puberty increases androgenic signalling and cell proliferation.”

“Plasma T and DHT concentrations and the VP absolute and relative weights were significantly higher in the animals exposed to caffeine compared with the control animals.”experiment.


Nicotine, most common in tobacco, is a damn androgenic compound. It increases all androgens and inhibits aromatase, especially in the brain. There are downsides other than health to it as well though – it messes up sperm production and mobility. This doesn’t affect androgens in the experiments out there though. I’m not telling you to use nicotine, light some cigs, or puff on a cigar, just giving you the data.

“Cigarette smoke (obtained using methylene chloride and aqueous traps) and tobacco leaves (70% ethanol extract; Nicotiana tabacum L.) also potently inhibited aromatase.” – study.

An experiment found out that nicotine blocks brain aromatase.

“Smoking can reduce or completely cancel the efficacy of orally administered estrogens.”study.

“Nicotine was also observed to yield a concentration-dependent inhibition of the stimulation by thyrotrophin-releasing hormone (TRH) of prolactin promoter activity.”experiment.

This experiment here found out that nicotine and it’s metabolites inhibit the conversion of androgens to estrogens.

“Nicotine, cotinine (a major metabolite of nicotine), and anabasine (a minor component of cigarette tobacco) all inhibited androstenedione conversion to estrogen in a dose-dependent fashion.”

What makes nicotine androgenic is nicotine and it’s metabolite – cotinine prevent the breakdown of DHT to it’s less potent form – 3 alpha-androstanediol, and this accumulates more DHT in the bloodstream.

“When microsomal fractions were incubated for 1 hour with and without nicotine and cotinine, enzyme activity of 3 alpha-hydroxysteroid dehydrogenase was significantly suppressed.”

“Nicotine and cotinine are competitive inhibitors of the 3 alpha-hydroxysteroid dehydrogenase, an important enzyme involved in the metabolism of DHT and produce an accumulation of DHT.”experiment.

P.S. Nicotine gum produces these effects as well but its less potent than tobacco.

Vitamin E

Vitamin E is an antioxidant with functions involving enzymatic activities, gene expression, and neurological function.

Vitamin E is a studied vitamin I found that inhibits aromatase without inhibiting 5 alpha reductase. Vitamin E does reduce androgen signaling but it does so without affecting androgen metabolism.

“Vitamin E treatment did not influence steroid 5-α-reductase expression in the prostate tumors. Vitamin E, however, significantly reduced aromatase expression, suggesting reduced estrogen synthesis.

“Neither IGF-I nor the ROS generating iNOS or NADPH oxidase were affected by vitamin E.”

“Vitamin E reduced androgen signaling without affecting androgen metabolism.”experiment.

“Dietary supplementation of vitamin E may reduce a woman’s risk of developing breast cancer.”

Alpha-Tocopherol is the most biologically active form of vitamin E.”

“A dose-dependent inhibition of cell proliferation was found in estrogen receptor (ER)-positive cells showing a potent suppression of growth at 100 microM vitamin E in MCF-7 (53%) and T47D (75%) cells.”

“Vitamin E reduced significantly the response of both cell lines to estrogen (10 nM), and cell proliferation was decreased in MCF-7 and T47D cells by 69% and 84%.”study.

Get a vitamin E supplement here.

Moderate Dose Zinc

Good old zinc inhibits 5 alpha reductase at doses higher than 54mg, at least in vitro in this experiment. Then at low-moderate doses it inhibits aromatase without inhibiting 5 alpha, it even increases 5 alpha. And then a deficiency in zinc lowers androgens and increases estrogens.

To get your bang for the buck with zinc:

  1. Fix a zinc deficiency asap
  2. Eat a good amount of red meat daily or supplement with a zinc supplement in 20-50mg doses
  3. Don’t go too high on zinc (according to a vitro study keep it <54mg)

“Prolactin concentrations significantly fell below basal levels in all subjects in response to the increase in plasma zinc levels, as compared to the controls.”study.

“Hepatic conversion of testosterone to dihydrotestosterone was significantly less, but formation of estradiol from testosterone was significantly greater in rats fed the zinc-deficient diet.”

“A significantly higher level of estrogen receptor in zinc-deficient rats than in pair-fed controls and a significantly lower level of androgen binding sites in rats fed the zinc-deficient diet  than in pair-fed control rats.”experiment.

“When zinc is added at low concentrations the 5 alpha-reduction of testosterone is increased but at higher cation concentrations the metabolism is significantly inhibited.” – experiment.


Niacinamide aka nicotinamide is the amide of nicotinic acid (vitamin B3 / niacin). Nicotinamide is a water-soluble vitamin and is part of the vitamin B group. Nicotinic acid, also known as niacin, is converted to nicotinamide.

“Cells were treated with nicotinamide or sirtinol, the level of estrogen receptor alpha mRNA in T47D cells was reduced after 48 h of 100 μM sirtinol treatment. The level of estrogen receptor alpha mRNA in MCF-7 cells was also reduced after treatment with sirtinol (100 μM) and nicotinamide (20 mM).”

“These data suggest that inhibition of SIRT1, a class III HDAC, suppresses estrogen receptor alpha expression at both mRNA and protein levels.”experiment.

“Estrogen receptor inhibitor ICI 182,780 and SIRT1 inhibitor niacinamide could block SIRT1’s protective effect.”

“SIRT1 functions as an important regulator of estrogen-mediated cardiomyocyte protection during AngII-induced heart hypertrophy and injury.”experiment.

Then there’s a good amount of evidence that niacinamide is androgenic (source).

“SIRT1 antagonists induce endogenous androgen receptor expression and enhance DHT-mediated androgen receptor expression.”

“Androgen receptor expression and DHT signaling are regulated by nicotinamide.”

“Nicotinamide, a noncompetitive inhibitor of Sir2, induced expression of the endogenous androgen-responsive androgen receptor gene.”experiment.

This makes niacinamide inhibit aromatase without inhibiting 5 alpha reductase.


That’s about all – the 5 ways to inhibit aromatase without inhibiting 5 alpha reductase.


  1. Brayden

    Doesnt vitamin e succinate block dht through inhibiting 5 ar?
    How would this differ from’ normal ‘vitamin e? If it reduces androgen signaling this is not good for someone like me suffering from post finasteride/saw palmetto
    Im open to suggestions

    1. Author

      Reduces estrogen more than it affects androgens. Higher androgen to estrogen ratio.

  2. Dave

    What dose zinc is good? I eat 8 oz red meat daily. Which equals around 15mg…should I aim for a little higher? Like 30 to 40mg for better benefits?

  3. Ashley

    I noticed you mention zinc lowers dht at doses higher than 54mg which is true, but even 20mg is too high if you have dht deficiency. Be very careful you should not be supplementing with zinc as it inhibits dht at anything higher than 5mg. Eating 2-3 eggs a day is fine as they contain trace amounts of zinc less than 3 mg in 3 eggs.

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