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Home > Health Conditions > Aromatization

Aromatization/Gynecomastia

Related Topics:

• chrysin / I3C / DIM / testosterone

• Arimidex (anastrozole) / Aromasin (exemestane) / Femara (letrozole) / Nolvadex (tamoxifen) / Faslodex (fulvestrant)

Prescription aromatase inhibitors:

• Arimidex at International Anti-aging Systems
• Femara at International Anti-aging Systems
• Letrozole at OffshoreRX.com

The Really Important Stuff:

• Anastrozole (Arimidex) - anabolic-androgenic-steroids.com - "Anastrozole (Arimidex) is the aromatase inhibitor of choice ...With moderate doses of testosterone 0.5 mg/day is usually sufficient and in some cases may be too much" - Femara (letrozole) may not have been available at the time this article was written.
• Chrysin: Is It An Effective Aromatase Inhibitor? - vrp.com - "Unfortunately, there does not appear to be any effective natural inhibitor of aromatase"

• Aromatase Inhibition Offers Little Benefit, Possible Harm to Men With Lo... - Medscape, 12/22/09 - "The inescapable conclusion from these data is that the 50% increase in testosterone levels was trumped by the much more modest 20% reduction in estradiol levels, leading to negative skeletal effects of anastrozole therapy in aging men" - Note:  I'm not sure that thought this though thoroughly.  Mortally in men is best when estrogen is around 25pg/mL.  I suspect that most have higher estrogen than that.  See:

  • High, Low Estradiol Levels and Mortality in Men With Systolic HF - Medscape, 5/19/09 - "Both low and high serum levels of estradiol, compared with mid-range levels, are significantly and independently associated with increased all-cause mortality in men with chronic systolic heart failure"
    Serum Estradiol Concentration Quintiles as Predictors of All-Cause Mortality in Men (With Quintile 3 as the Reference Group)

    Parameter	Quintile 1	Quintile 2	Quintile 3	Quintile 4	Quintile 5
    Estradiol concentration (pg/mL)	<12.903	12.90–21.79	21.80–30.11	30.12–37.39	>37.40
    3-y survival* (%)	44.6	65.8	82.4	79.0	63.6
    Quintile as mortality predictor,* HR (95% CI) vs quintile 3	4.17 (2.33–7.45)	2.15 (1.16–3.99)	--	1.22 (0.64–2.31)	2.33 (1.30–4.18)

    HR= hazard ratio
• High, Low Estradiol Levels and Mortality in Men With Systolic HF - Medscape, 5/19/09 - "Both low and high serum levels of estradiol, compared with mid-range levels, are significantly and independently associated with increased all-cause mortality in men with chronic systolic heart failure" - Note:  See my aromatization page for ways to reduce it.  I take a quarter tablet of letrozole every day.  See letrozole at OffshoreRX.com.
  Serum Estradiol Concentration Quintiles as Predictors of All-Cause Mortality in Men (With Quintile 3 as the Reference Group)

  Parameter	Quintile 1	Quintile 2	Quintile 3	Quintile 4	Quintile 5
  Estradiol concentration (pg/mL)	<12.903	12.90–21.79	21.80–30.11	30.12–37.39	>37.40
  3-y survival* (%)	44.6	65.8	82.4	79.0	63.6
  Quintile as mortality predictor,* HR (95% CI) vs quintile 3	4.17 (2.33–7.45)	2.15 (1.16–3.99)	--	1.22 (0.64–2.31)	2.33 (1.30–4.18)

  HR= hazard ratio
• Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism - Eur J Endocrinol. 2008 May;158(5):741-7 - "Isolated hypogonadotropic hypogonadism (IHH) is frequently observed in severely obese men, probably as a result of increased estradiol (E(2)) production and E(2)-mediated negative feedback on pituitary LH secretion. Aromatase inhibitors can reverse this process ... treated with 2.5 mg letrozole once a week for 6 months ... Six weeks of treatment reduced total E(2) from 123+/-11 to 58+/-7 pmol/l (P<0.001, mean+/-s.e.m.), and increased serum LH from 4.4+/-0.6 to 11.1+/-1.5 U/l (P<0.001). Total testosterone rose from 5.9+/-0.5 to 19.6+/-1.4 nmol/l (P<0.001), and free testosterone from 163+/-13 to 604+/-50 pmol/l (P<0.001). Total testosterone rose to within the normal range in all subjects, whereas free testosterone rose to supraphysiological levels in 7 out of 12 men ... Letrozole 2.5 mg once a week produced a sustained normalization of serum total testosterone in obese men with IHH. However, free testosterone frequently rose to supraphysiological levels. Therefore, a starting dose <2.5 mg once a week is recommended" - See Femara (letrozole) at OffshoreRX.  I've been taking a quarter table a day but it sounds like that's way to much an a quarter tablet every other day might be best which comes to 2.5 mg every 8 days.  People complain about the hassle to get doctors to prescribe testosterone.  It sounds like letrozole will give you the same or better numbers without the hassle.  Plus testosterone replacement increases estrogen but letrozole has the advantage of decreasing it.  See my aromatization page.
• Long-term Consequences of the Aromatase Inhibitors - Medscape, 11/16/05 - "The "short-term toxicities," such as vasomotor symptoms, venothromboemboli, and gynecologic complications, favor the use of AIs. However, long-term bone loss, altered lipid profiles, and possible compromise in sexual functioning appear to be adversely affected by the AIs"
• Letrozole normalizes serum testosterone in severely obese men with hypogonadotropic hypogonadism - Diabetes Obes Metab. 2005 May;7(3):211-5 - "Six weeks of treatment decreased serum estradiol from 120 +/- 20 to 70 +/- 9 pmol/l (p = 0.006). None of the subjects developed an estradiol level of less than 40 pmol/l. LH increased from 4.5 +/- 0.8 to 14.8 +/- 2.3 U/l (p < 0.001). Total testosterone rose from 7.5 +/- 1.0 to 23.8 +/- 3.0 nmol/l (p < 0.001) without a concomitant change in sex hormone-binding globulin level. Those treated with Letrozole 17.5 mg per week had an excessive LH response" - Note:  A half tablet per day would be 8.75 mg/week.  I believe 40 pmol/l of estradiol is 11.54 pg/mL and the normal value for men is 10 to 52 pg/mL (Quest says 10 to 50).  The way I read that, testosterone tripled.  I take a half tablet a day of Femara (letrozole).  See Femara at International Anti-aging Systems or Letrozole at OffshoreRX.com.
• Can Broccoli Prevent Lupus? - WebMD, 11/6/03 - "I3C is believed to act as an anti-estrogen ... I3C-fed mice had far fewer kidney problems than the mice whose diets were not supplemented, and researchers say this is the reason that they lived much longer. Kidney disease is one of the main, life-threatening complications of lupus" - See iHerb I3C products.
• Why Testosterone Levels Decline  - Life Extension Magazine, 11/99 - "Clinical studies using testosterone injections, creams, or patches have often failed to provide a long-lasting, libido-enhancing effect in aging men (98). We now know why. The testosterone can be converted to estrogen. The estrogen is then taken up by testosterone receptor sites in cells throughout the body. When an estrogen molecule occupies a testosterone receptor site on a cell membrane, it blocks the ability of serum testosterone to induce a healthy hormonal signal. It does not matter how much serum free testosterone is available if excess estrogen is competing for the same cellular receptor sites"
• Correcting A Hormone Imbalance  - Life Extension Magazine, 11/99 - "If all of the above fail to increase free testosterone and lower excess estradiol, then ask your doctor to prescribe the potent aromatase inhibiting drug Arimidex (anastrozole) in the very low dose of one-half (0.5 mg) mg, twice a week"
• Androgel prescribing information - androgel.com - "Serum estradiol (E2) concentrations increased significantly within 30 days of starting treatment with AndroGel® 5 or 10 G/day and remained elevated throughout the treatment period but remained within the normal range for eugonadal men" - Yeah, but what if you are taking DHEA and what about testosterone/estrogen ratios.   See:
  • Biotransformation of oral dehydroepiandrosterone in elderly men: significant increase in circulating estrogens - J Clin Endocrinol Metab 1999 Jun;84(6):2170-6 - "Serum testosterone and dihydrotestosterone remained unchanged after DHEA administration. In contrast, 17beta-estradiol and estrone significantly increased in a dose-dependent manner to concentrations still within the upper normal range for men [placebo vs. 50 mg DHEA vs. 100 mg DHEA; AUC 0-12 h for 17beta-estradiol, 510 +/- 198 vs. 635 +/- 156 vs. 700 +/- 209 pmol/L x h (P < 0.0001); AUC 0-12 h for estrone, 1443 +/- 269 vs. 2537 +/- 434 vs. 3254 +/- 671 pmol/L x h (P < 0.0001)]"
• Estrogen: The Unrecognized Male Hormone - IAS
• Testosterone Deficiency & Depression, Does DHEA Raise the Levels of Bioavailable Testosterone in Men? - Life Extension Magazine, 8/02 - "Some men on testosterone drug replacement therapy develop dangerously high estrogen levels. Estrogen can be suppressed by taking an aromatase-inhibiting drug like Arimidex (0.5 mg twice a week) or using a supplement like Super Mira Forte (six capsules daily)" - See Arimidex at International Anti-aging Systems.
• Biotransformation of oral dehydroepiandrosterone in elderly men: significant increase in circulating estrogens - J Clin Endocrinol Metab 1999 Jun;84(6):2170-6 - "Serum testosterone and dihydrotestosterone remained unchanged after DHEA administration. In contrast, 17beta-estradiol and estrone significantly increased in a dose-dependent manner to concentrations still within the upper normal range for men [placebo vs. 50 mg DHEA vs. 100 mg DHEA; AUC 0-12 h for 17beta-estradiol, 510 +/- 198 vs. 635 +/- 156 vs. 700 +/- 209 pmol/L x h (P < 0.0001); AUC 0-12 h for estrone, 1443 +/- 269 vs. 2537 +/- 434 vs. 3254 +/- 671 pmol/L x h (P < 0.0001)]" - That's a 40% increase in the bad estrogen!  On top of that, if you are taking testosterone, that increases estrogen also.
• Aromatase Inhibition Corrects Endocrinopathy In Infertile Men - Doctor's Guide, 4/9/01 - "investigators found that men with severe infertility had significantly lower testosterone (328 versus 543 ng/dl) and significantly higher oestradiol (58.4 versus 43.5 ng/l) than the fertile controls. As a result, the infertile men had much lower testosterone-to-oestradiol ratios ... These abnormalities were corrected in the 45 men who received testolactone and their testosterone-to-oestradiol ratios rose into the normal range"
• Evidence of a Treatable Endocrinopathy in Infertile Men - J. of Urology, 3/01 - "We identified an endocrinopathy in men with severe male factor infertility that is characterized by a decreased serum testosterone-to-estradiol ratio. This ratio can be corrected by aromatase inhibition, resulting in a significant improvement in semen parameters in oligospermic patients"
• Replenish Testosterone Naturally - Life Extension Magazine, 1/00 - "Through a variety of mechanisms, aging men suffer from the dual effects of having too little testosterone and excess estrogen. The result is a testosterone/ estrogen imbalance that can severely inhibit sexual desire and performance ... Too much estrogen plays havoc with a man's sex life by binding to testosterone receptor sites and may contribute to the over-production of SHBG. SHBG binds free testosterone in a way that makes it unavailable to receptor sites in the brain, nerves and genitals."
• Estrogen suppression in males: metabolic effects - J Clin Endocrinol Metab. 2001 Apr;86(4):1836-8 - "First, a dose-response study of 12 males (mean age, 16.1 +/- 0.3 yr) was conducted, and blood withdrawn at baseline and after 10 days of oral Arimidex given as two different doses (either 0.5 or 1 mg) in random order with a 14-day washout in between. A sensitive estradiol (E2) assay showed an approximately 50% decrease in E2 concentrations with either of the two doses ... There was a 58% increase in serum T"
• Male Hormone Modulation Therapy  - Life Extension Magazine, 11/99 - "One cause of hormone imbalance in men is that their testosterone is increasingly converted to estrogen. One report showed that estrogen levels of the average 54-year-old man are higher than those of the average 59-year-old woman . . . . High levels of estrogen have been implicated as a cause of benign prostatic hypertrophy (BPH)"
• Arimidex - Rxlist.com - "ARIMIDEX 1 mg, reduced estradiol by approximately 70% within 24 hours and by approximately 80% after 14 days of daily dosing"

News & Research:

• Obesity may influence heart function through sex hormones - Science Daily, 4/27/13 - "suggests effects on heart function in healthy men with artificially raised estrogen levels and artificially lowered testosterone levels to mimic an obese state ... Estradiol, an estrogen, is primarily known as a female hormone but it also circulates at very low levels in men. Testosterone is converted to estradiol by the enzyme aromatase, the activity of which might be increased in obesity leading to raised estradiol and reduced testosterone ... The men with obesity-related changes in sex hormones exhibited altered heart function ... We found that after increasing the estrogen levels and decreasing the testosterone levels in men for one week the deformation of the left heart chamber was significantly altered"
• The Inhibitory Effects of the Standardized Extracts of Ginkgo biloba on Aromatase Activity in JEG-3 Human Choriocarcinoma Cells - Phytother Res. 2013 Jan 21 - "There are many endocrine adjuvant therapies for breast cancer patients that are categorized according to their mechanisms. Among them, aromatase inhibitors (AIs) that block the synthesis of estrogens have proven superiority compared with tamoxifen and have replaced it as a first-line hormonal therapy. However, AIs also have limitations due to their side effects - increased rate of bone loss and musculoskeletal complaints ... The extracts of Ginkgo biloba (EGb), which contain phytochemicals from the tree, had biphasic effects for estrogens and osteoporosis-inhibiting activities in our previous experiments. In this study, we explored the possibility of EGb as an AI and their mechanisms. Aromatase activities were inhibited by EGb both in JEG-3 cells and in recombinant CYP19 microsomes ... From these results, we concluded that EGb could act as an AI at both the enzyme and transcriptional levels" - See Ginkgo biloba products at iHerb.
• Age Trends in Estradiol and Estrone Levels Measured Using Liquid Chromatography Tandem Mass Spectrometry in Community-Dwelling Men of the Framingham Heart Study - J Gerontol A Biol Sci Med Sci. 2012 Oct 25 - "Estrone was positively associated with smoking, BMI, and testosterone, and total and free estradiol with diabetes, BMI, testosterone, and comorbid conditions; additionally, free estradiol was associated negatively with smoking ... Men in the highest quintile of estrone levels had significantly higher age and BMI, and a higher prevalence of smoking, diabetes, and cardiovascular disease than others, whereas those in the highest quintile of estradiol had higher BMI than others ... Total estrone and estradiol levels in men, measured using liquid chromatography tandem mass spectrometry, revealed significant age-related increases that were only partially accounted for by cross-sectional differences in BMI, diabetes status, and other comorbidities and health behaviors"
• Higher endogenous estrogen levels in 70-year-old women and men: an endogenous response to counteract developing atherosclerosis? - Menopause. 2012 Sep 17 - "Low androgen levels, high aromatase enzyme activity (estrone [E1]/androstenedione and estradiol [E2]/testosterone), high E2/E1 ratio, and high estrogen levels (E1, E2, estriol, and E2/sex hormone-binding globulin) were consistently associated (often significantly) with a more unhealthy artery wall (thick intima, thin media, and high IMT ratio) in both sexes. Consistently strong associations were found between the aromatase index E2/testosterone and intima, media, and the IMT ratio. For IMT ratio, in both men (rs = 0.52) and women (rs = 0.58), P was <0.001 for both and remained significant after adjustment for cardiovascular disease risk factors and the Framingham risk score (both P < 0.01)" - Note:  I'm not a doctor but it seems like taking a quarter tablet of letrozole every second or third day as I'm doing would control this.  See letrozole at International Anti-aging Systems.
• Reducing the side effects of treatment for prostate cancer - Science Daily, 8/24/12 - "tamoxifen reduced the risk of both gynecomastia and breast pain at 3, 6, 9, and 12 months of treatment compared to men who received no treatment. Overall, treatment with tamoxifen was more successful in reducing breast symptoms than treatment with an aromatase inhibitor (anastrazole) or radiotherapy" - Note:  They left out Femara (letrozole).
• Drugs for hair loss and benign prostatic hyperplasia may result in loss of libido, erectile dysfunction in men - Science Daily, 1/11/11 - "5a-reductase inhibitors (5a-RIs), while improving urinary symptoms in patients with benign prostatic hyperplasia (BPH) and possible hair loss prevention, produces significant adverse effects in some individuals including loss of libido, erectile dysfunction (ED), ejaculatory dysfunction and potential depression" - Note:  That goes back and forth.  One study claimed that finasteride improved sex after after six months of taking it.  Regarding gynaecomastia, if you're taking low dose letrozole to increase testosterone and to prevent aromatization it many also help prevent gynaecomastia.
  • Prostate Drug May Not Dim Sex - WebMD, 6/26/07 - "Six months after the men started taking their assigned drugs, the survey scores were about three points higher for the men taking Proscar. By the end of the study, that gap narrowed to about two points"
  • Prostate Drug Doesn't Limit Sexual Function In Most Men - Science Daily, 7/19/07 - "The study suggests that finasteride will cause little or no sexual dysfunction for most men who decide to take it"
  • Ask a Medical Question - Can letrozole cure gynecomastia - JustAnswer - "Letrozole may be effective in preventing and reversing the gynaecomastia provided it is used early enough in steroid induced gynaecomastia" - See letrozole at OffshoreRx.com.  I believe the recommended dose is something like a quarter tablet every three days but don't quote me on it.  That's what I take.
• Sex Hormones and the Risk of Incident Prostate Cancer - Urology. 2010 May 6 - "Serum testosterone, estradiol, estrone, and sex hormone-binding globulin were assayed at baseline ... the mean age was 73 years. Higher serum estrone was strongly related to an increased risk of prostate cancer: compared with men in the lower quartile, the risk of prostate cancer among those in the highest 3 quartiles (>24.9 pg/dL) was nearly 4-fold higher (adjusted heart rate = 3.93, CI: 1.61-9.57). Other sex hormones were not associated with the risk of prostate cancer" - The following results for estrone are for women.   I didn't find any results for men but see the "For Aromatization (in males):" section on my letrozole page.
  • Letrozole suppresses plasma estradiol and estrone sulphate more completely than anastrozole in postmenopausal women with breast cancer - J Clin Oncol. 2008 Apr 1;26(10):1671-6 - "Letrozole reduces plasma E2 and E1S levels to a significantly greater extent than anastrozole" - See Femara (letrozole)at OffshoreRX.
  • Influence of letrozole and anastrozole on total body aromatization and plasma estrogen levels in postmenopausal breast cancer patients evaluated in a randomized, cross-over study - J Clin Oncol. 2002 Feb 1;20(3):751-7 - "estrone (E(1)), estradiol (E(2)), and estrone sulfate (E(1)S) ... Treatment with anastrozole suppressed plasma levels of E(1), E(2), and E(1)S by a mean of 81.0%, 84.9%, and 93.5%, respectively, whereas treatment with letrozole caused a corresponding decrease of 84.3%, 87.8% and 98.0%, respectively. The suppression of E(1) and E(1)S was found to be significantly better during treatment with letrozole compared with anastrozole"
• Aromatase Explains Why Testosterone Increases Breast Cancer Rate - Cancer Epidemiol Biomarkers Prev. 2009 May 12 - "All of this is consistent with the increase in breast cancer observed in postmenopausal women who had higher serum testosterone levels being due to the resulting increase in the local level of estradiol in the breast tissue"
• Obesity Linked To Hormone Imbalance That Impacts Sexual Quality Of Life - Science Daily, 3/3/09 - "In our study population, we found that lower testosterone levels and diminished ratings for sexual quality of life were correlated with increased BMI ... Subjects who lost weight through bariatric surgery experienced a reduction in estradiol levels, an increase in testosterone levels and an increase in ratings of sexual quality of life" - Another way to increase testosterone and decrease estradiol is with letrozole.  I take a quarter tablet every other day.
• Short-term aromatase inhibition: effects on glucose metabolism and serum leptin levels in young and elderly men - Eur J Endocrinol. 2008 Dec 2 - "Ten elderly and nine young healthy men were randomized to receive letrozole 2.5 mg daily or placebo for 28 days in a crossover design. Results: Both in young and elderly men, active treatment significantly increased serum testosterone (+128 and +99%, resp.) and decreased estradiol levels (-41 and -62%, resp.). Fasting glucose and insulin levels decreased in young men after active intervention (-7 and -37%, resp.) compared to placebo. Leptin levels fell markedly in both age groups (-24 and -25%, resp.), while adiponectin levels were not affected by the intervention. Lipid profile was slightly impaired in both groups, with increasing LDL-cholesterol levels (+14%) in the younger age group and 10% lower levels of ApoA1 in the elderly. A decline in IGF-1 levels (-15%) was observed in the younger age group. No changes in weight or BMI were observed in either young or old men" - Note:  I take a quarter tablet of letrozole every other day to prevent aromatization.  See letrozole at OffshoreRX.com.
• Sex Hormones Link To Heart Risk - Science Daily, 8/31/08 - "one of the sex hormones - estradiol - was associated positively with total cholesterol and negatively with HDL-cholesterol. Circulating concentrations of another sex hormone - estrone - showed strong positive associations with both total cholesterol and LDL-cholesterol ... Thus, men with the highest concentrations of estrone and estradiol may have the highest level of cardiovascular risk as their levels of detrimental LDL-cholesterol are high whilst their cardio-protective HDL-cholesterol is low"
• Letrozole suppresses plasma estradiol and estrone sulphate more completely than anastrozole in postmenopausal women with breast cancer - J Clin Oncol. 2008 Apr 1;26(10):1671-6 - "Letrozole reduces plasma E2 and E1S levels to a significantly greater extent than anastrozole" - See Femara (letrozole) at OffshoreRX.
• Male Breast Enlargement May Be Common - WebMD, 9/19/07 - "Underlying the condition is an imbalance of estrogen and testosterone. When estrogen levels get too high, the breasts can begin to grow"
• The red clover (Trifolium pratense) isoflavone biochanin A inhibits aromatase activity and expression - Br J Nutr. 2007 Aug 29;:1-8 - "Biochanin A is an isoflavone isolated from red clover (Trifolium pratense) ... Isoflavones resemble the structure of oestrogen, and display agonistic and antagonistic interactions with the oestrogen receptor. Overexposure of oestrogen is a major contributing factor in the development of breast cancer ... In the present study the effect of biochanin A on the gene regulation and enzyme activity of aromatase was investigated. By assaying MCF-7 cells stably transfected with CYP19, biochanin A inhibited aromatase activity and hampered cell growth attributing to the enzyme activity" - See red clover products at iHerb.
• Management of Gynaecomastia: An Update - Medscape, 8/7/07
• Elevated Serum Estradiol Ups Stroke Risks - Physician's Weekly, 5/7/07 - "High levels of serum estradiol may increase the risk of stroke in elderly men"
• High Estrogen Levels Associated With Dementia In Older Men; No Association Observed With Testosterone - Science Daily, 7/24/06 - "Levels of bioavailable testosterone were not associated with risk of cognitive decline and incident dementia," they report. "In contrast, higher levels of bioavailable estradiol were associated with an increased risk for cognitive decline and Alzheimer's disease." For each standard deviation increase in estradiol level, the risk for the disease went up by 25 percent" - I take a quarter tablet of Femara (OffshoreRx.com) to keep estrogen low. - Ben
• Drug Combination May Slow Male Breast Cancer Growth - Science Daily, 7/7/06
• Five Years on Anastrozole Can Promote Progression to Osteoporosis - Medscape, 6/12/06 - "Women taking anastrozole also had about a 40% increased risk of fractures while on the study ... At 5 years, women taking anastrozole lost 6.1% of BMD at the hip and 7.2% at the spine ... women with a normal BMD at baseline did not develop osteoporosis" - It's something to think about for men taking anastrozole for aromatization.
• Shrinking Male Breasts? - Dr. Weil, 4/12/06
• Declining Estradiol Levels More Predictive of Fracture Risk Than Low Testosterone in Aging Men - Doctor's Guide, 10/8/04 - "While low levels of free testosterone are a predictor of hip-bone loss, declines in estradiol levels play a stronger role than testosterone"
• New-Onset Depression Linked to Tamoxifen - Doctor's Guide, 5/25/03 - "Results show a rate of new-onset depression of 17.82% in the tamoxifen group and 14.34% in the no-tamoxifen group" - It seems like the same might be true for men taking tamoxifen to prevent aromatization.
• Procedure Removes Excess Breast Fat In Men - TheSanDiegoChannel.com, 5/14/03
• Several Options Available for Androgen Replacement Therapy - Doctor's Guide, 4/8/03 - "Side effects of exogenous androgen therapies are mood changes, polycythemia, gynecomastia, exacerbation of sleep apnea, and in some patients, acne"
• I have read that Indole-3-Carbinol (I3C) actually increases the activity of aromatase enzyme and that DIM does not - Life Extension Magazine, 3/01 - "In one study, men received I3C for one week; a profile of 13 estrogens was measured. The results were that I3C significantly increased the urinary excretion of C-2 estrogens. The urinary concentrations of nearly all other estrogen metabolites, including levels of estradiol, estrone, estriol and 16 alpha-hydroxyestrone, were lower after I3C treatment [J Natl Cancer Inst 1997 May 21;89(10):718-23]. On the other hand, studies have shown that DIM can actually induce aromatase activity with a two-fold increase [Toxicol Sci 2001 May;61(1):40-8]" - The following are the two references for that statement:
• 2,3,7,8-Tetrachlorodibenzo-p-dioxin and Diindolylmethanes Differentially Induce Cytochrome P450 1A1, 1B1, and 19 in H295R Human Adrenocortical Carcinoma Cells - Toxicol Sci 2001 May;61(1):40-8 - "DIM, but not TCDD, induced aromatase activity with an apparently maximal 2-fold increase at 10 µM; higher concentrations of DIM and many of its analogs were cytotoxic"
• Changes in levels of urinary estrogen metabolites after oral indole-3- carbinol treatment in humans - J Natl Cancer Inst 1997 May 21;89(10):718-23 - "In both men and women, I3C significantly increased the urinary excretion of C-2 estrogens. The urinary concentrations of nearly all other estrogen metabolites, including levels of estradiol, estrone, estriol, and 16alpha- hydroxyestrone, were lower after I3C treatment" - So if C-2 estrogens are increased, is that bad in men?  I don't know. The following are all I could find:
  • Estrogen Metabolism - immunacare.com - "C-2 metabolites are essentially devoid of peripheral biological activity, as shown in studies on uterine weight, gonadotrophin secretion, and cell proliferation {1}. 2-Hydroxyestrogen has even been found to exert a modest anti-estrogenic effect {2,3}, and has been called "the good estrogen" {4}. The 16a-hydroxylated metabolites, 16a-hydroxyestrone (16OHE1) and estriol (E3), are estrogen agonists {5}."
  • Effects of Pesticides on the Ratio of 16/2-Hydroxyestrone: A Biologic Marker of Breast Cancer Risk - Environmental Health Perspectives 103, Supplement 7, October 1995 -"Estradiol metabolism proceeds by hydroxylation at one of two mutually exclusive sites at C-2 and C-16. The catechol pathway yields the weakly estrogenic 2-hydroxyestrone (2-OHE1), which inhibits breast cell proliferation" - If that means, and I think it does, that the C-2 metabolites inhibit breast cell growth, that would definitely be a good thing for men.
• Estrogen - the Unrecognized Male Hormone - Rick Cohen, MD
• The Cruciferous Choice: DIM or I3C? - Michael A. Zeligs, M.D. - "It is well documented that estrogen accumulates in the prostate gland starting at age 50 (42) and that estrogen is associated with the degree of prostate enlargement ... Using DIM in men avoids accelerating testosterone metabolism, especially regarding unwanted conversion of testosterone into estrogen. In the safety study reported (11), I3C and not DIM increased activity of "aromatase" (CYP19), the enzyme responsible for converting testosterone into estrogen"
• Tamoxifen, Raloxifene Prove Effective In Pre-Pubertal Gynecomastia - Doctor's Guide, 7/12/01
• Anti-Aromatase Agents Cost-Effective For Women With Metastatic Breast Cancer - Doctor's Guide, 5/15/01
• Aromatase Inhibition Does Not Interfere With Serum Lipids In Metastatic Breast Cancer - Doctor's Guide, 5/14/01
• Aromatase Inhibition Corrects Endocrinopathy In Infertile Men - Doctor's Guide, 4/9/01 - "investigators found that men with severe infertility had significantly lower testosterone (328 versus 543 ng/dl) and significantly higher oestradiol (58.4 versus 43.5 ng/l) than the fertile controls. As a result, the infertile men had much lower testosterone-to-oestradiol ratios ... These abnormalities were corrected in the 45 men who received testolactone and their testosterone-to-oestradiol ratios rose into the normal range"
• Replenish Testosterone Naturally - Life Extension Magazine, 1/00
• Evidence of a Treatable Endocrinopathy in Infertile Men - J. of Urology, 3/01 - "We identified an endocrinopathy in men with severe male factor infertility that is characterized by a decreased serum testosterone-to-estradiol ratio. This ratio can be corrected by aromatase inhibition, resulting in a significant improvement in semen parameters in oligospermic patients"
• Femara (Letrozole) Significantly More Effective Than Tamoxifen In Treating Advanced Breast Cancer - Doctor's Guide, 12/7/00
• Diagnosis and Management of Male Breast Enlargement in Patients With HIV/AIDS - Medscape, 12/00
• Aromasin Now Available In US For Advanced Breast Cancer - Doctor's Guide, 1/24/00
• Should Aging Men Take Testosterone Drugs?  - Life Extension Magazine, 11/99
• Inhibition of aromatase activity by flavonoids - Arch Pharm Res. 1999 Jun;22(3):309-12 - "Over 50% of the flavonoids significantly inhibited aromatase activity, with greatest activity being demonstrated with apigenin (IC50: 0.9 microg/mL), chrysin (IC50: 1.1 microg/mL), and hesperetin (IC50: 1.0 microg/mL)"
• I3C/DIM - Recurrent Respiratory Papillomatosis Foundation
• Flavonoid inhibition of aromatase enzyme activity in human preadipocytes - J Steroid Biochem Mol Biol. 1993 Sep;46(3):381-8 - "Chrysin, the most potent of the naturally-occurring flavonoids, was similar in potency and effectiveness to AG, a pharmaceutical aromatase inhibitor used clinically in cases of estrogen-dependent carcinoma."
• Inhibition of human estrogen synthetase (aromatase) by flavones - Science. 1984 Sep 7;225(4666):1032-4
• Testolactone (Teslac) - mesomorphosis.com
• Mesterolone (Proviron) - mesomorphosis.com
• Anastrozole (Arimidex) - anabolic-androgenic-steroids.com - "Anastrozole (Arimidex) is the aromatase inhibitor of choice"
• Anti-estrogens - mesomorphosis.com - "The most commonly used aromatase inhibitor in bodybuilding is aminoglutethimide (Cytadren)"