induce production of sex hormone-binding
globulin in the liver and in this way influence
sex hormone metabolism and biological effects.
Indeed, Gorbach and Goldin (1987) measured
urinary, faecal and plasma levels of oestrogens in
pre- and postmenopausal women eating differ-
ent diets. Premenopausal US women consuming
a ‘Western’ diet composed of 40% fat and low
fibre were compared with age-matched vegetari-
ans eating 30% of their energy intake as fat and
a high-fibre diet. The researchers found that
the vegetarian women excreted threefold more
oestrogen in their faeces, had lower urinary
oestrogen excretion, and had 15–20% lower
plasma oestrogen than the omnivorous women.
When pre- and postmenopausal women eating a
Western diet were compared with Asian immi-
grants eating a very low fat diet (20–25% of total
energy from fat), similar results were found,
except that the plasma oestrogen levels were 30%
lower among the Orientals than in the Western
omnivore group. Correlation analysis of dietary
components and plasma oestrogen showed that
plasma oestrogen was positively associated with
fat intake and negatively associated with dietary
fibre. The authors concluded that diets high in
fibre, like a vegetarian diet, can alter the route of
excretion of oestrogen by influencing the entero-
hepatic circulation and thus influence plasma
levels of oestrogen. In a similar study, Pedersen et
al.(1991) examined the effect of different nutri-
tional patterns on menstrual regularity in pre-
menopausal women. Forty-one non-vegetarian
and 34 vegetarian women were recruited and
completed a questionnaire regarding menstrual
history and a 3-day dietary record. The reported
incidence of menstrual irregularity was 4.9%
among the non-vegetarians and 26.5% among
the vegetarians. The vegetarian group consumed
significantly more polyunsaturated fatty acids,
carbohydrates, vitamin B 6 and dietary fibre,
whereas the non-vegetarians consumed signifi-
cantly more caffeine, cholesterol, saturated fatty
acids and alcohol. Logistic regression analysis
showed that the probability of menstrual regu-
larity among all subjects was positively corre-
lated with increasing protein and cholesterol
452 special considerations
intakes. The probability of developing menstrual
irregularities was negatively correlated with
increasing dietary fibre and increasing amounts
of magnesium in the diet. This study is consistent
with the notion that premenopausal vegetarian
women as a group have decreased circulating
oestrogen concentrations.
Additional data from Adlercreutz et al.(1986a)
have also found that vegetarians may be excret-
ing more oestrogen than omnivores: they investi-
gated the possible effects of variations in dietary
fibre intake on oestrogen metabolism in young
Finnish women through one winter and one
summer. Eleven of the subjects were lactovege-
tarians, while 12 were omnivorous. Within the
groups there was a seasonal variation in fibre
intake. The vegetarian group consumed more
fibre (P<0.02), more grains (P<0.02) and more
vegetables (P<0.02) during the winter than
during the summer. The excretion of oestrogens
was remarkably constant in the omnivorous
group, while the vegetarian group had a signifi-
cant seasonal variation of total and individual
catecho-oestrogens and estrone (P<0.05–0.005).
There were no differences between the groups in
excretion of total or individual urinary oestro-
gens in any season or between mean values for
both seasons, but a significant negative correla-
tion was found between dietary intake of total
grain fibre per kilogram of body weight and the
excretion of individual oestrogens were found.
These studies are consistent with the notion that
menstrual regularity can be influenced by spe-
cific dietary nutrients that may have a direct
effect on oestrogen.Hormonal responses of a vegetarian lifestyle
on males
Most of the data collected on diet and hormone
relationships among vegetarians is on women,
and information on males is sparse. Howie and
Shultz (1985) studied the relationship between
dietary nutrients and plama testosterone, 5-a-
dihydrotestosterone, oestradiol-17-b, luteinizing
hormone, and prolactin levels in 12 Seventh Day
Adventist vegetarian, 10 Seventh Day Adventist