Study Suggests Bad Diet May Harm a Woman’s Fertility

Can a bad diet hurt a woman’s chances of conceiving? A 2018 Australian study suggests that eating too much fast food and not enough fresh fruit will make it harder for women to get pregnant.

“Interest in the impact of diet and environmental toxins on fertility is growing,” notes fertility specialist Rebecca Flyckt, MD, commenting on the study.

“I do believe diet can influence fertility. But the problem is separating diet out from factors such as smoking, obesity, poor sleep and lack of exercise — all of which can also influence fertility.”

Female fertility more common

Fifteen percent of all couples have trouble conceiving. In 70 to 80 percent of those cases, it’s because the woman has one of these issues:

• A structural problem (fibroids, cysts, endometriosis, scar tissue from infections) can make it harder for eggs to travel through the fallopian tubes.
• A hormonal problem (polycystic ovary syndrome, thyroid disease) can interfere with a woman’s reproductive cycle.
• Advanced maternal age can make it harder to produce viable eggs. (A woman’s fertility drops dramatically in her mid- to late 30s.)

How the study worked

In the study, midwives asked 5,628 women at their first post-delivery visit about their intake of fruit, leafy greens, fish and fast foods in the month before they conceived.

Then investigators looked at how long (with one year as the endpoint) it took the women to get pregnant.

The less often the women consumed fresh fruit, and the more often they consumed fast food, the longer it took them to conceive, they found.

Why fruit and not veggies?

The fact that eating leafy greens and fish had no impact on the time it took women to conceive in this study surprised Dr. Flyckt.

“I wouldn’t run out and buy a grocery cart full of only fresh fruit to improve your fertility,” she says. “Vegetables are good for you, too.”

Other studies have found the Mediterranean diet — which incorporates fresh veggies, fruit, healthy fats and whole grains — beneficial for fertility.

Study limitations

While this study showed a relationship between fast food, fresh fruit and fertility, it failed to show cause and effect.

That’s because the women were asked to look back and recall what they ate.

“Any study based on recall is subject to bias,” says Dr. Flyckt. “The women who conceived easily might assume, ‘It must have been my good diet,’ while those who struggled might assume, ‘It must have been my terrible diet.’”

To prove cause and effect, you’d need a prospective study measuring how changes in behavior influence fertility going forward, she says.

The researchers acknowledged that this study did not look at the impact of vegetables other than leafy greens, or the possibility of male infertility.

‘Good, clean living’ helps

Still, “this study reinforces what many fertility specialists see in clinical practice: that good, clean living translates to better outcomes,” says Dr. Flyckt.

For men and women who hope to conceive, she recommends:

• Eating a healthy diet with fresh fruit and veggies
• Avoiding fast food, processed foods, and sugary sweets and sodas
• Avoiding alcohol, cigarettes and drugs
• Getting good and consistent sleep
• Going outdoors and exercising your body

Begin making these lifestyle changes about three months before you start trying to conceive, she advises. “It takes 90 days for the egg that a woman ovulates in any given month to start the process of maturing,” explains Dr. Flyckt.

No magic bullet

This study is one more vote against fast food’s deleterious effects on the body, and one more vote in support of a healthy diet, she says. But it’s important to keep the influence of diet in perspective.

“Many of us working in the field wish there were a diet that could help our patients conceive. But going vegan, gluten-free or ketogenic, or giving up dairy, is not a magic bullet,” she says.

Many who struggle to conceive need treatment for real, identifiable medical problems.

“A healthy diet is a helpful addition to treatment. But we wouldn’t want patients to waste six or nine months trying out a diet if it means they’ll delay treatment,” says Dr. Flyckt.