Nutr Cancer. 1988 ; 11(2): 101-6.

The binding of blood-borne estrogens in normal vegetarian and omnivorous women and the risk of breast cancer.

Fentiman IS, Caleffi M, Wang DY, Hampson SJ, Hoare SA, Clark GM, Moore JW, Bruning P, Bonfrer JM.

ICRF Clinical Oncology Unit, Guy's Hospital, London, UK.

Serial blood samples were taken at two-hour intervals over a 24-hour period from 25 premenopausal vegetarians (12 vegans and 13 ovolactovegetarians) and from 21 omnivorous controls. All members of the former group had been on a vegetarian diet for a minimum of three years. The mean proportion of estradiol unbound to blood proteins was similar in both vegetarians (1.26%) and meat eaters (1.16%). However, the amount bound to albumin was significantly raised in vegetarians (50.1% vs. 43.1%, p less than 0.009), whereas that bound to sex hormone-binding globulin (SHBG) was correspondingly lower (48.7% vs. 55.8%, p = 0.01). Mean levels of SHBG were similar in vegetarians (59.9 nmole/l) and omnivores (62.0 nmole/l), as was the total amount of free fatty acid (0.42 mmole/l for both). Within the vegetarian group, no differences were detected between vegans and ovolactovegetarians.