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Testosterone, sex hormone-binding globulin, calculated free testosterone, and oestradiol in male vegans and omnivores
Abstract and Figures
Total testosterone (T), total oestradiol (E2) and sex hormone-binding globulin (SHBG) concentrations were measured in plasma samples from fifty-one male vegans and fifty-seven omnivores of similar age. Free T concentration was estimated by calculation. In comparison with the omnivores, the vegans had 7% higher total T (P = 0.250), 23% higher SHBG (P = 0.001), 3% lower free T (P = 0.580), and 11% higher E2 (P = 0.194). In a subset of eighteen vegans and twenty-two omnivores for whom 4 d diet records were available, there were statistically significant correlations between T and polyunsaturated fatty acids (r 0.37), SHBG and fat (r 0.43 for total fat, 0.46 for saturated fatty acids and 0.33 for polyunsaturated fatty acids), and SHBG and alcohol (r-0.39). It is concluded that a vegan diet causes a substantial increase in SHBG but has little effect on total or free T or on E2.
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... Moreover, few studies have investigated the association between vegetarianism and sex hormone levels, which revealed that adherence to a vegetarian diet could increase the level of sex hormone-binding globulin (SHBG) and decrease urinary levels of estrogen in postmenopausal women, but they reported dissimilar results on the effect of vegetarian diet on sex hormones in pre-menopausal population; furthermore, the possible impact of vegetarian diet on fertility regarding sex hormones, was not well-established in these articles (14,(33)(34)(35)(36). ...
... Overall, 73 articles were selected for full-text screening. Finally, 20 eligible articles (14,28,31,33,34,(37)(38)(39)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54) were included for qualitative synthesis, of which 16 were appropriate for quantitative synthesis (28, 31, 33, 34, 37-39, 44, 45, 47-49, 51-54). The detailed selection process is shown in Figure 1. ...
... Detailed study characteristics are presented in Table 1. Studies were published between 1982 and 2021 and were conducted mainly in the USA (n = 8) (28,39,(47)(48)(49)(51)(52)(53), followed by the UK (n = 5) (33,34,43,44,54) and Canada (n = 2) (14, 37). Also, one study was reported from each one of the following countries (Chile (46), Italy (45), India (50), Belgium (38), and Germany (31)). ...
Background:
An increasing number of people have adhered to vegetarian diet since several years ago. Nowadays, the favorable effect of this dietary pattern on metabolic diseases is well established, but its impact on fertility and reproductive health as a serious health concern is not clear yet. Hence, we aim to summarize existing evidence, regarding the possible association between a vegetarian diet, and fertility as measured by key indicators such as sperm quality, and sex hormone levels.
Methods:
We systematically searched online databases, including PubMed, ISI, Scopus, and Google Scholar, up to December 1st, 2022 using relevant keywords. We included observational studies that compared semen quality, sex hormone levels, and infertility in people who adhered to a vegetarian diet versus. Heterogeneity between studies was assessed using I2 and Chi-square tests. Standardized mean differences (SMD) using a random/fixed model were calculated to assess outcomes between vegetarians and omnivores in included articles.
Results:
Finally, out of 972 documents that were retrieved, 20 articles met our inclusion criteria, and 16 were eligible for quantitative synthesis. Results of meta-analyses showed that there were no significant differences between vegetarians and omnivores in terms of semen quality parameters, including total sperm count, total and progressive sperm motility, sperm morphology, and sperm concentration. Seven studies on female sex hormones profiles were eligible for meta-analysis. The only significant difference was the lower level of plasma estrone in vegetarians (Pooled SMD: -0.56; 95% CI: -1.08, -0.05; P-value = 0.03) compared to the omnivores. Furthermore, our meta-analysis revealed significantly higher sex-hormone-binding globulin (SHBG) levels in vegetarians men than in omnivores (Pooled SMD: 0.52; 95% CI: 0.18, 0.86; P-value = 0.002).
Conclusion:
Despite the numerous health benefits of a vegetarian diet, our review suggested that there were no conclusive positive or negative associations between vegetarian diet and semen quality, sex hormone levels, and infertility. Further studies are recommended to better understand vegetarian dietary pattern effect on infertility and reproductive health. This article is protected by copyright. All rights reserved.
... The current data are of great importance for a comprehensive understanding of the effects of a well-designed vegan diet on highly physically active and healthy long-term adult vegans. The data, which are particularly interesting, belong to the category of those that researchers compare with an omnivorous diet as the standard dietary pattern suggested by dietary guidelines (e.g., dietary intakes of protein, eicosapentaenoic omega-3 fatty acids (EPAs) and docosahexaenoic omega-3 fatty acids (DHAs), vitamin B12 and D, calcium, iron, zinc, and iodine [3,13], serum vitamin B12, 25-hydroxyvitamin D (25 (OH)D) and iron, total testosterone status in men, insulin-like growth factor 1 (IGF-1), homocysteine, the omega-3 index (indicator of EPA and DHA intake in erythrocyte membranes), and iodine in urine) [3,[14][15][16][17][18]. ...
... Contrary to common belief, subjects on a vegan diet had significantly higher total testosterone levels than subjects on omnivorous (by 13%) and lacto-vegetarian (by 8%) diets [14]. In a smaller study that included 51 vegans and 57 omnivorous subjects, vegans had 7% higher total testosterone values [15]. Finally, in a recent study, the researchers found no significant difference in serum total testosterone values between omnivores and those who had a plant-based diet [84]. ...
Adopting a vegan diet as a long-term diet has recently become a new global trend among healthy and physically active adult populations. Unfortunately, scarce scientific data are available on the nutritional and health status and lifestyle patterns of long-term highly physically active ve-gan populations. In the present case study, we present the results of the nutritional, health and lifestyle status of a highly physically active and health-conscious long-term vegan man. The following research methods were used to assess overall health and lifestyle status: (i) analysis of blood serum (selected cardiovascular risk factors (e.g., lipoproteins, triglycerides, glucose, glycosylated haemo-globin, and homocysteine), safety markers (e.g., insulin-like growth factor 1, total testosterone, high-sensitivity C-reactive protein, uric acid, and creatinine), and micronutrients (e.g., vitamin B12, 25-hydroxyvitamin D, iron and ferritin); (ii) erythrocyte membranes analysis (omega-3 index); (iii) urine sample analysis (creatinine and iodine); (iv) blood pressure measurement; (v) bioimpedance and densitometry measurement (initial and current anthropometric variables and body composition); (vi) seven-day weighted dietary records (energy and nutrient intake from regular foods only were compared with the recommended daily intake); and (vii) standardized questionnaires (socio-demographic status, economic status and lifestyle status). The most remarkable results related to dietary intake were high energy (4420 kcal/d) and fibre intake (143 g/d) and nutritional sufficiency from foods only compared with dietary recommendations, with the exception of eicosapentaenoic omega-3 fatty acids and docosahexaenoic omega-3 fatty acids, vitamin B12 and vitamin D. Overall dietary acid load (DAL) scores, calculated from the potential renal acid load (PRAL) and net endog-enous acid production (NEAPF), were rated as lower compared to those of other dietary patterns. In addition, we found that the overall health and lifestyle status of the subject was satisfactory, with some minor deviations that we interpreted.
... Unfortunately, in most papers comparing testosterone levels there are significant differences in BMI between the groups, reflecting around 10 kg in weight. Although patients are mostly in the normal BMI range, the results need to be critically evaluated as the primary differences described are changes in SHBG in terms of higher concentrations in vegans compared to omnivores [22] and even compared to vegetarians [23] or in vegetarians compared to omnivores [24]. The effect on free testosterone is described inconsistently, from decreases to no changes, but these data are virtually impossible to interpret as the lower SHBG groups have significantly higher weight. ...
The great popularity of various diets in recent years has led us to reflect on their suitability for our health. The aim of this communication is to review current knowledge on the influence of the most well-known diets on the concentrations of the main steroids and to consider possible mechanisms. The influence of diet on hormone concentrations is expected, but the literature data on this topic are inconsistent and yield conflicting results. The main problem in evaluating these influences is the change in weight that a change in diet induces. This effect needs to be filtered out in order to discover interesting associations between diet and steroid hormones. This is illustrated by the example of the effects of ketogenic diets on testosterone levels in men, where the direct effect of the diet is to reduce testosterone levels, but a number of papers have described increases that are due to diet-related weight loss and the modification of obesity-induced changes. A second major driver is the change in circadian rhythm, and it is necessary to assess hormonal changes induced by changing the time of day of the diet. Such shifts within the circadian rhythm rather than due to a particular type of diet itself are documented by changes in the circadian rhythm of cortisol.
... Contrary findings have been also reported. In a study of 108 men with a mean age of 41 years higher PUFA intake was related to higher testosterone concentrations [37]. In another study of 209 men aged 18-23 years, higher intakes of MUFA and TFA were associated with lower testosterone concentration [23]. ...
Background/Objectives
Average testosterone concentrations in men have declined over the last few decades. The reasons for this are not fully known, but changes in dietary fat quality have been suggested to have a role. This study aimed to investigate the associations of different dietary fatty acids with serum androgen concentrations.
Subjects/Methods
A total of 2546 men with a mean age of 53 from the Kuopio Ischaemic Heart Disease Risk Factor Study were included in this cross-sectional study. Associations between dietary saturated (SFA), monounsaturated (MUFA), polyunsaturated (PUFA) and trans (TFA) fatty acids and concentrations of serum total and free testosterone and steroid hormone binding globulin (SHBG) were analyzed with analysis of covariance and linear regression analysis. Associations of isocaloric replacement of nutrients and androgen concentrations were analyzed with multivariate nutrient-density models.
Results
After adjustment for age, examination year and energy intake, higher SFA intake was associated with higher serum total and free testosterone and SHBG concentrations, and higher PUFA intake with lower concentrations. However, the associations were attenuated and not statistically significant after further adjustments for potential confounders. MUFA and TFA intakes were not associated with androgen concentrations. In isocaloric substitution models, replacing dietary protein with SFA was associated with higher serum total testosterone and SHBG concentrations. After excluding men with history of CVD or diabetes ( n = 1021), no statistically significant associations were found.
Conclusions
Dietary fat quality was not independently associated with serum androgen concentrations in middle-aged men. However, replacing protein with SFA may be associated with higher serum androgen concentrations.
... 11 However, these old studies are burdened by small sample sizes and some methodological limits. [11][12][13][14] In more recent times, many other diet components have been evaluated so far in their influence on androgen production, such as soy flavonoids, 15 coffee, 16,17 and low carbohydrate intake. [18][19][20] Comprehensively, which components of diet and with what weight could really influence T production in humans is still a matter of debate. ...
Background
Low testosterone concentrations affect 2–13% of adult males, with a direct association between reduction in testosterone (T) concentrations and cardiovascular events. Lifestyle habits have been linked to visceral fat accumulation and endocrine disorders like secondary hypogonadism. Alcohol intake has also been a topic of debate, with studies showing a detrimental effect on sperm production and underlying mechanisms. This meta‐analysis aims to comprehensively evaluate the effect of alcohol consumption on T serum concentrations in adult men.
Methods
The literature search included only controlled clinical trials comparing men who drink alcohol to men who do not, or who assumed placebo or nonalcoholic beverages. The primary outcome was the comparison of total testosterone serum concentrations between the study and control groups. The publications were examined for publication bias using Egger's test.
Results
Twenty‐one studies were included in the analysis for a total of 30 trials that examined the effects of alcohol consumption on testosterone level in 10,199 subjects. The meta‐analysis showed that alcohol consumption overall is related to significant reduction in circulating concentrations of total testosterone (mean difference [MD] = −4.02; 95% CI −6.30, −1.73), free T (MD = −0.17; 95% CI −0.23, –0.12), sex hormone binding globulin (SHBG) (MD = −1.94; 95% CI −3.37, −0.48), an increase in estradiol (E2) (MD = 7.65; 95% CI 1.06, 14.23) and neutral effect on luteinizing hormone (LH) (MD = −0.15; 95% CI −0.36, 0.06), independently by age, body mass index (BMI), E2, and LH serum concentrations and alcohol intake. However, these results are evident only in healthy men exposed to chronic alcohol consumption and not in those with a recognized diagnosis of alcohol use disorder or after acute alcohol intake.
Conclusion
This study suggests how chronic alcohol consumption may inhibit the gonadal axis in healthy men, although the exact pathophysiological mechanisms connecting alcohol exposure and steroidogenesis are still not completely clarified.
Sex hormone‐binding globulin (SHBG) is a homodimeric glycoprotein produced by the human liver and secreted into the systemic circulation where it binds with high affinity sex steroids regulating their availability in blood and accessibility to target tissues. Plasma SHBG levels are altered in metabolic disorders such as obesity, anorexia, and insulin resistance. Several reports have shown that diets in terms of total calories or fat, fiber, or protein content can alter plasma SHBG levels. However, there are many components in a diet that can affect SHBG gene expression in the liver. In order to unravel the molecular mechanisms by which diets regulate SHBG production, it would be necessary to analyze single diet components and/or nutritional factors. This review summarizes the recent advances in identifying different nutritional factors regulating SHBG production and the related molecular mechanism, as well as the clinical implications.
Wide-ranging and inclusive, this text provides an invaluable review of an expansive selection of topics in human evolution, variation and adaptability for professionals and students in biological anthropology, evolutionary biology, medical sciences and psychology. The chapters are organized around four broad themes, with sections devoted to phenotypic and genetic variation within and between human populations, reproductive physiology and behavior, growth and development, and human health from evolutionary and ecological perspectives. An introductory section provides readers with the historical, theoretical and methodological foundations needed to understand the more complex ideas presented later. Two hundred discussion questions provide starting points for class debate and assignments to test student understanding.
Wide-ranging and inclusive, this text provides an invaluable review of an expansive selection of topics in human evolution, variation and adaptability for professionals and students in biological anthropology, evolutionary biology, medical sciences and psychology. The chapters are organized around four broad themes, with sections devoted to phenotypic and genetic variation within and between human populations, reproductive physiology and behavior, growth and development, and human health from evolutionary and ecological perspectives. An introductory section provides readers with the historical, theoretical and methodological foundations needed to understand the more complex ideas presented later. Two hundred discussion questions provide starting points for class debate and assignments to test student understanding.
Wide-ranging and inclusive, this text provides an invaluable review of an expansive selection of topics in human evolution, variation and adaptability for professionals and students in biological anthropology, evolutionary biology, medical sciences and psychology. The chapters are organized around four broad themes, with sections devoted to phenotypic and genetic variation within and between human populations, reproductive physiology and behavior, growth and development, and human health from evolutionary and ecological perspectives. An introductory section provides readers with the historical, theoretical and methodological foundations needed to understand the more complex ideas presented later. Two hundred discussion questions provide starting points for class debate and assignments to test student understanding.
Wide-ranging and inclusive, this text provides an invaluable review of an expansive selection of topics in human evolution, variation and adaptability for professionals and students in biological anthropology, evolutionary biology, medical sciences and psychology. The chapters are organized around four broad themes, with sections devoted to phenotypic and genetic variation within and between human populations, reproductive physiology and behavior, growth and development, and human health from evolutionary and ecological perspectives. An introductory section provides readers with the historical, theoretical and methodological foundations needed to understand the more complex ideas presented later. Two hundred discussion questions provide starting points for class debate and assignments to test student understanding.
The British tables of Paul and Southgate provide by far the most extensive introductory and explanatory material with the tables. As it is a resource which is often utilized, we thought it important to mention here. Since, however, the introduction is 52 pages long and is already in the English language we refer you to the original. A sample page is presented (see Table 1).
PIP
A review was made to understand how plasma binding protein might influence sex-hormone action in target tissues. Steroids are predominately bound to plasma proteins and only unbound steroids enter the cells. Sex-hormone-binding globulin (SHBG) binds to both the main circulating steroid T and E2 but changes in SHBG concentrations exert significant results. Increased SHBG levels increase estrogen production and decreases T activity; whereas, increased androgens increase T action and inhibit SHBG production. These disturbances in hormone maintenance may lead to abnormal adult sex differentiation such as hirsutism and forms of hynaecomastia. By developing SHBG concentration measurement methods-responses of hirsutism to glucocorticoid or estrogem may be assessed. In addition, the effect of thyroid hormones on SHBG may also have therapeutic implications in endocrine disease.
Several experimental studies have suggested that diet can alter the production and metabolism of steroids in men. The purpose of this study was to determine the levels of unconjugated steroids and steroid glucuronides as well as sex hormone-binding globulin (SHBG) among normal adult men who were either omnivorous or vegetarians. The participants were white volunteers ranging from 25–35 years of age and the blood samples were taken between 0900 h and 1000 h and between 1600 h and 1700 h for two consecutive days. No significant statistical change was found in plasma dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, dihydrotestosterone and estradiol levels. Vegetarian group showed a higher levels of sex hormone-binding globulin (SHBG) while the free androgen index (FAI; calculated by the ratio testosterone/SHBG) was lower in this group. Although the concentrations of androsterone glucuronide were higher in vegetarian group, the vegetarians had a 25–50% lower level of androstane-3α,17β-diol glucuronide and androstane-3β,17β-diol glucuronide. Our data further indicate that both, androstane-3α,17β-diol glucuronide and androstane-3β,17β-diol glucuronide concentrations are significantly correlated with SHBG levels and with the FAI values. The increases in androstane-3α,17β-diol glucuronide and androstane-3β,17β-diol glucuronide levels in the omnivorous group are probably a consequence of the elevation of the FAI. Our data suggest that in a vegetarian group, less testosterone is available for androgenic action.
This study reports the effect of a vegetarian diet and dexamethasone administration on the hormone status of healthy Caucasian men and premenopausal women. A lower nocturnal release of prolactin and testosterone occurred in men fed a vegetarian diet, while in women, dexamethasone administration decreased the nocturnal release of prolactin and caused a greater decrease of plasma dehydroepiandrosterone (DHEA). These results show that diet modification can induce hormonal changes, If similar changes occur in patients with breast and/or prostatic cancer, diet modification may be of benefit in these patients with tumors known to be hormonally dependent.
The concentration of sex hormones and their binding in the plasma were measured in male patients (20-40 years old), who weighed 140-170% (I), 170-200% (II) and >200% (III) of their ideal weight. Correlated to body weight, there is a reduction in the total concentration of testosterone, which, in the very obese patients, amounts to 41% (in group I: 85%, in group II: 68%; P<0.001) of that found in an age-matched healthy control group of subjects of 'normal' body weight (90-115% of the ideal body weight; n: 20). Androstenedione values show only a trend downwards (from 0.94 to 0.72 ng/ml plasma), while the oestrogen values increase significantly; oestrone increases by a factor of 1.09 (I), 1.43 (II; P<0.001) and 1.69 (III; P<0.001) and oestradiol by 1.13, 1.43 P<0.001) and 1.76 (P<0.001), respectively. Despite the fall in testosterone there are no clinical signs of hypogonadism, as SHBG (from 5.1±0.8 in the controls to 2.4±0.6x10-8 Mol/l in the very obese patients of group III) and the protein-bound fraction of testosterone also decrease. As a result the concentration of free testosterone remains constant (120 pg/ml), except in the very obese (93 pg/ml). Becuase of the different affinity of the binding proteins for testosterone and oestradiol the ratio of free oestradiol: free testosterone shifts less strongly in favour of the feminizing hormone (11.1x10-3 in group III as compared to 4.1x10-3 in the controls), than is suggested by the total hormone concentrations. A disturbance in the gonadal function of the pituitary gland or the testes is not present, since the concentration of LH is normal and the testicular response to HCG in very obese patients adequate (increase of testosterone by a factor of 3.11 as compared to 2.23 in the controls). The cause of the decrease in testosterone and SHBG is unknown, while the increase of plasma oestrogens is likely to be due to the increased conversion of androgens to oestrogens in the adipose tissue, which clearly plays an important role for plasma concentrations of sex hormones in obese patients.
Several experimental studies have suggested that diet can alter the production and metabolism of steroids in men. The purpose of this study was to determine the levels of unconjugated steroids and steroid glucuronides as well as sex hormone-binding globulin (SHBG) among normal adult men who were either omnivorous or vegetarians. The participants were white volunteers ranging from 25-35 years of age and the blood samples were taken between 0900 h and 1000 h and between 1600 h and 1700 h for two consecutive days. No significant statistical change was found in plasma dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, dihydrotestosterone and estradiol levels. Vegetarian group showed a higher levels of sex hormone-binding globulin (SHBG) while the free androgen index (FAI; calculated by the ratio testosterone/SHBG) was lower in this group. Although the concentrations of androsterone glucuronide were higher in vegetarian group, the vegetarians had a 25-50% lower level of androstane-3 alpha, 17 beta-diol glucuronide and androstane-3 beta,17 beta-diol glucuronide. Our data further indicate that both, androstane-3 alpha,17 beta-diol glucuronide and androstane-3 beta,17 beta-diol glucuronide concentrations are significantly correlated with SHBG levels and with the FAI values. The increases in androstane-3 alpha,17 beta-diol glucuronide and androstane-3 beta,17 beta-diol glucuronide levels in the omnivorous group are probably a consequence of the elevation of the FAI. Our data suggest that in a vegetarian group, less testosterone is available for androgenic action.
Nagase analbuminemic rats have normal reproductive capacity, normal apparent libido, and normal serum concentrations of LH and FSH. Therefore, it is reasonable to assume that intracellular sex steroid hormone concentrations are normal or at least adequate to maintain normal reproductive function in these rats. To test whether intracellular testosterone concentrations in these rats are maintained by the circulating concentration of free or free-plus-weakly-bound testosterone, we measured the concentrations of total testosterone, free testosterone, and non-sex-hormone-binding-globulin-bound testosterone in sera from five adult male Nagase analbuminemic rats and from five age- and sex-matched controls. We found that the analbuminemic rats had markedly decreased serum concentrations of total and non-sex-hormone-binding-globulin-bound testosterone, but normal serum concentrations of free testosterone. These results suggest that intracellular concentrations of testosterone in biologically relevant organs of the rat are maintained by the concentration of free rather than free-plus-weakly-bound testosterone in plasma, in accord with the free hormone hypothesis.