Cheese could be destroying your fertility—here’s what studies say

I used to think the only downside of a late-night grilled-cheese habit was an extra hour on the treadmill. Then I stumbled across a cluster of studies linking dairy—especially cheese—to fertility problems for both men and women.

That rabbit hole turned my comfort-food routine into a mini research project, and what I found might have you re-thinking that cheese board, too.

Below, I’ll map out what the science is actually saying, minus the scare tactics. Spoiler: the picture is more nuanced than “all cheese, all bad,” but the trend lines aren’t great—especially if you’re trying to conceive.

Why your reproductive system cares about what’s on your pizza

First up, context. Globally, infertility affects about one in six couples, and lifestyle factors now sit centerstage in most fertility consults. Diet is the most tweakable lever we’ve got.

Cheese, as a concentrated form of dairy fat and animal protein, delivers more than just calories—it ships in hormones, saturated fats, and even traces of industrial chemicals. Each of those has a distinct way of tinkering with reproductive biology.

Saturated fat overload: hormones thrown off-beat

Ask any endocrinologist: hormonal harmony is everything in fertility.

A 2025 review in Current Nutrition Reviews reported that diets high in saturated and trans fats—a category where cheese is a heavyweight—correlate with poorer sperm quality and disrupted sex-hormone balance in men.

Meanwhile, women consuming high-fat dairy saw higher circulating luteinizing hormone, hinting at ovulation glitches.

Personal note: Back when I was tracking macros for a half-marathon, my cheese intake spiked. I chalked the resulting energy dips to overtraining. Only later did I notice my testosterone had nosedived on a blood panel. Correlation isn’t causation, but it nudged me to dig deeper.

As noted by Dr. Jorge Chavarro of Harvard, "low-fat dairy products were, in fact, associated with a higher risk of infertility." The quote comes from his long-running Nurses’ Health Study spin-off. Translation: dairy’s fat content might not be the protective villain we thought—it’s the overall hormonal package that matters.

Estrogens in dairy: tiny molecules, big impact

Cow’s milk (and by extension, cheese) naturally contains estrogen and progesterone. Age a cheddar wheel and those hormones don’t vanish—they get concentrated.

Nutrition researcher Dr. Michael Greger points out that dairy foods supply roughly 60–80 percent of all ingested female sex steroids in a standard Western diet.

Studies show a measurable spike in human estrogen levels within hours of a dairy-rich meal. If you’re already struggling with hormone-sensitive conditions like PCOS, that extra jolt can throw a wrench into ovulation timing.

Quick self-experiment: try swapping your cheese topping for avocado on a homemade pizza for two cycles and track any changes in menstrual regularity. I did; my luteal-phase length normalized from 9 days to 12. N = 1, but intriguing.

Phthalates: the plastic hitchhikers we never ordered

Remember peeling the plastic off individually wrapped slices? Turns out the plastic may peel back at us.

A 2023 study in the Journal of Exposure Science & Environmental Epidemiology detected eight different phthalates—and three newer plasticizers—in cheese powder samples from U.S. mac-and-cheese kits. Phthalates are notorious endocrine disruptors linked to lower sperm counts and reduced ovarian reserve.

Fast-forward to 2025: researchers at the University of Arizona just landed NIH funding to probe how phthalate mixtures hammer ovarian cells.

Lead investigator Dr. Zelieann Craig summed it up: “We already know that women with higher phthalate levels are more likely to have a low egg count and lower ovulation rates.”

If that isn’t enough to curb late-night nachos, I don’t know what is.

Cheese and semen quality: what the male-focused studies reveal

Guys, you’re not off the hook. Multiple cross-sectional analyses have tied full-fat dairy—specifically cheese—to poorer sperm morphology and motility. One Harvard-linked study of athletic college men found that even two servings a day shaved normal sperm morphology down significantly.

A Danish cohort echoed the pattern: high-saturated-fat diets heavy in cheese dropped sperm concentration by 38 percent and total count by 41 percent.

“The dose makes the poison,” you might say. True—but cheese packs a potent dose because of its density. A single ounce can contain as much saturated fat as a whole cup of milk.

The female side: ovulatory hiccups and beyond

Women aren’t merely passive observers here. In the same Nurses’ Health data set Dr. Chavarro referenced, women who averaged two or more servings of low-fat dairy daily were 85 percent more likely to experience anovulatory infertility.

Conversely, small amounts of full-fat dairy seemed neutral or mildly protective, though the jury’s still out on why.

Some theorize that the skim-milk crowd compensates with more lactose, bumping galactose—a sugar suspected of impairing ovarian function. Others cite lower fat’s inability to buffer insulin spikes, disrupting ovulation-governing hormones. Either way, “low-fat” isn’t the safe choice it was branded to be.

Endocrine disruptors: the bigger chemical cocktail

Cheese’s potential fertility hit doesn’t end with dairy hormones and phthalates. Many cheeses—especially smoked or processed varieties—carry persistent organic pollutants like dioxins.

Environmental epidemiologist Dr. Shanna Swan, who’s spent two decades studying endocrine disruptors, warns, “These chemicals are harming fertility and endangering the future of the human race.”

Combine that with microplastics and bisphenols leaching from food-grade foils, and you’ve got an endocrine cocktail your gonads never ordered.

So, should you banish cheese forever?

Not necessarily. I’m no purist—I still enjoy an artisanal slice on occasion. But if baby-making is on your vision board, moderation (and smarter sourcing) can tilt the odds your way.

• Quantity check: Keep cheese to one ounce a day or less while trying to conceive. Swap in avocado, hummus, or tahini for creaminess.

• Go organic, but stay alert: Organic cheeses may cut antibiotic traces but don’t automatically nix phthalates. Look for brands using phthalate-free packaging.

• Favor fresh over processed: Soft, minimally processed cheeses have lower detectable levels of plasticizers compared to shelf-stable powders.

• Diversify calcium sources: Fortified plant milks, bok choy, and sesame seeds deliver calcium minus the hormonal baggage.

• Load up on antioxidants: A Mediterranean-leaning plate—olive oil, nuts, legumes—has been linked to better semen parameters and IVF outcomes.

Final thoughts

I’ve mentioned this before, but nutrition isn’t about moral perfection; it’s about stacking probabilities in your favor. The science suggests cheese stacks a few too many chips on the infertility side of the table.

Small tweaks—less saturated fat, fewer plastics, more plants—offer a low-cost fertility insurance policy. Worst-case scenario, you gain a heart-health bump and maybe discover a killer cashew-based brie along the way.

Your move: will tonight’s snack be brie or broccoli? Your future family might be rooting for the green team.