Sex Hormone Binding Globulin
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Sex Hormone Binding Globulin (SHBG) is a protein that binds to sex steroid hormones like testosterone and estrogen, preventing them from being in their free or active forms. Here are key insights discussed by and guests on the :
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Caffeine's Impact: Caffeine intake can increase SHBG, slightly reducing levels of free testosterone and estradiol. These effects are minor and typically not a concern at moderate doses of caffeine, but it's something to keep in mind to optimize hormone levels without excess intake 1.
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Nutritional Influence: Adequate calorie and carbohydrate intake can modulate SHBG levels. Insulin, which rises with carbohydrate intake, inhibits SHBG, thus increasing free testosterone. Therefore, very low-carb diets can increase SHBG levels, reducing free testosterone 2 3.
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Oral Contraceptives: Taking oral estrogen (such as in birth control pills) raises SHBG, which can significantly reduce free testosterone levels. This reduction can lead to symptoms like decreased libido and vaginal dryness. Some women are particularly sensitive to these changes due to genetic factors 2 4.
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Testosterone Transporters: SHBG and albumin transport testosterone into cells. SHBG regulates the amount of free and bound testosterone, shuttling testosterone to specific tissues. Supplements like Tongkat Ali can help lower SHBG, potentially increasing free testosterone availability 5 3 6.
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Vitamin D and Boron: Supplementing with vitamin D and boron can support hormone profiles. Boron, in particular, can acutely lower SHBG levels, thus boosting free testosterone 7.
In summary, SHBG plays a crucial role in regulating free hormone levels, and factors like diet, caffeine intake, oral contraceptives, and specific supplements can influence its activity.
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