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Wednesday 26th June 2019

Caffeine affects women's oestrogen levels

31st January 2012

Caffeine seems to change the way women's levels of oestrogen vary over the course of a day, according to a recent US study.


The stimulant does not seem to affect ovulation, and the statistical link between the hormone and caffeine mainly seems to affect younger women.

Enrique Schisterman, an epidemiologist at the U.S. National Institutes of Health (NIH), said his team's results indicated that caffeine consumption among women of child-bearing age influenced oestrogen levels.

He said that, in the short term, variations in oestrogen levels among different groups did not appear to have any pronounced effects.

The hormone levels also tended to vary depending on the ethnic origin of the woman under consideration.

Women of East Asian descent were also affected differently from the other women studied.

For the study, the researchers recruited 250 women between the ages of 18 and 44.

Over two menstrual cycles, the researchers monitored the women's caffeine intake and levels of oestrogen.

Not all of the women drank coffee, so the researchers used milligrams as a way of measuring caffeine intake.

Besides coffee, women drank black tea, green tea, or caffeinated fizzy drinks.

The researchers found that 89% of women in the study consumed the equivalent of about 2 cups of coffee a day, or 200 milligrams.

The average caffeine intake was 90 milligrams per day.

Among women of East Asian descent, getting 200 milligrams of coffee tended to bring elevated oestrogen levels.

Among other ethnic groups of women, caffeine did not seem to have such a pronounced effect.

In addition, the results differed when the researchers made separate analyses of the individual sources of caffeine.

Getting a lot of caffeinated fizzy drinks, or drinking green tea, tended to elevate women's levels of oestrogen.

Schisterman said that variations in oestrogen tended to cause endometriosis and osteoporosis.

He said that long-term caffeine consumption could possibly affect women's long-term oestrogen levels, and that doctors needed to be aware of the caffeine consumption of female patients.

As for the reason why caffeine seemed to affect women differently, the researchers suggested that genetics might play a role.

Antioxidant levels in various drinks, or adding milk or sugar, might also affect the way the body metabolises the substances in the drinks.

Schisterman said that more research was needed, particularly in order to assess the long-term effects of caffeine intake in women.

Statistically, high caffeine intake is usually associated with lower rates of cancer.

However, drinking fizzy drinks is associated with many health problems, including diabetes and male impotence.


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