According to Gram Research analysis, men with lower folate status had reduced sperm quality in a 2026 study of 197 healthy young men. Specifically, men carrying a genetic variant called MTHFD1 1958 AA had 7.7% lower sperm movement and were 4.4 times more likely to have abnormal sperm patterns. While most men had adequate folate levels, the findings suggest this B vitamin plays an important role in male reproductive health.
A new study of 197 healthy young men found that those with lower folate levels—a B vitamin found in leafy greens and beans—had lower quality sperm. Researchers also discovered that certain genetic variations affecting how the body uses folate were connected to reduced sperm movement and abnormal sperm shape. While most men in the study had adequate folate levels, the findings suggest that this common B vitamin plays an important role in male fertility. The research adds to growing evidence that nutrition and genetics both influence reproductive health in men.
Key Statistics
A 2026 cross-sectional study of 197 healthy men found that those with the MTHFD1 1958 AA genetic variant had 7.7% reduced progressive sperm motility compared to men with the GG variant.
In the 2026 Led-Fertyl study of 197 men, only 1.5% had severe folate deficiency and 5.6% had low folate status, yet the genetic variant MTHFD1 1958 AA was associated with 4.4 times higher odds of abnormal sperm patterns.
A 2026 analysis of 197 healthy men aged 18-40 years showed that folate-related genetic variations may influence sperm quality more significantly than folate status alone in this population.
The Quick Take
- What they studied: Whether folate levels and specific genes that control folate use affect sperm quality in healthy young men
- Who participated: 197 healthy men aged 18-40 years recruited between 2021-2023. All participants were generally healthy with no known fertility problems at the time of the study.
- Key finding: Men with lower folate status had worse sperm quality. Additionally, men carrying a specific genetic variant (MTHFD1 1958 AA) had 7.7% lower sperm movement and were 4.4 times more likely to have abnormal sperm patterns compared to those with a different genetic version.
- What it means for you: If you’re a man concerned about fertility, ensuring adequate folate intake through diet or supplements may support sperm health. However, this is one study in a younger, healthy population—talk to a doctor about your individual situation, especially if you have fertility concerns.
The Research Details
This was a cross-sectional study, which means researchers took a snapshot in time of 197 healthy men and measured their folate levels, genetic makeup, and sperm quality all at once. They weren’t following men over time or comparing them to a control group—instead, they looked at whether the men with lower folate also had worse sperm quality.
The researchers measured folate in two ways: in blood plasma (the liquid part of blood) and in red blood cells, which shows both recent and long-term folate status. They also measured cobalamin (vitamin B12) and homocysteine (a compound related to B-vitamin metabolism). Additionally, they identified specific genetic variations that affect how efficiently the body uses these B vitamins.
Sperm quality was assessed using standard WHO (World Health Organization) criteria that measure sperm count, movement (motility), and shape (morphology). The researchers then used statistical analysis to determine whether folate status and genetic variations were connected to these sperm quality measures.
This research approach is important because it examines both environmental factors (folate intake/status) and genetic factors (inherited variations) together. Sperm production is a complex process that requires proper DNA synthesis and cell division, processes that depend heavily on folate. By measuring actual folate levels rather than just asking men about their diet, the study provides more reliable information. The genetic analysis helps explain why some men might be more vulnerable to folate deficiency’s effects on fertility.
Strengths: The study measured folate in multiple ways (plasma and red blood cells), included genetic testing, and used standardized sperm quality criteria. The sample size of 197 is reasonable for this type of research. Limitations: This is a snapshot study, not a long-term follow-up, so we can’t prove folate deficiency causes poor sperm quality—only that they’re associated. The study included only healthy young men, so results may not apply to older men or those with existing health conditions. The study was conducted in one location, which may limit how broadly the findings apply.
What the Results Show
Most men in the study had adequate folate levels. Only 1.5% had severe folate deficiency (plasma folate below 7 μmol/L), and 5.6% had low folate (below 15 μmol/L). Interestingly, these very low folate levels weren’t directly associated with worse sperm quality in this group.
However, a specific genetic variation called MTHFD1 1958 AA showed a clear connection to sperm problems. Men with this genetic variant had 7.7% lower progressive motility—meaning their sperm didn’t swim as well—compared to men with the GG variant. These men were also 4.4 times more likely to have an abnormal seminogram (an overall assessment of sperm quality showing problems with count, movement, or shape).
The study suggests that genetics may play a bigger role than folate status alone in determining sperm quality. Men with certain genetic variations may be more sensitive to even modest folate deficiency, even when their folate levels appear adequate by standard measures.
The study measured cobalamin (vitamin B12) and homocysteine levels but didn’t find strong associations between these and sperm quality. This suggests that folate’s effect on sperm may be more important than B12’s effect, though both vitamins work together in the body. The median red blood cell folate level (678.2 nmol/L) was in the normal range for most participants, indicating that most men were getting enough folate from their diet.
This research builds on earlier studies showing that folate is important for male fertility. Previous research has shown that folate deficiency can harm sperm production because folate is essential for DNA synthesis and cell division—processes critical during sperm development. This study adds new information by examining specific genetic variations that affect folate metabolism. The finding that genetics may matter more than folate status alone is relatively novel and suggests that future fertility assessments might benefit from considering both nutritional status and genetic factors.
The study has several important limitations. First, it’s a snapshot in time—researchers measured men once and looked for associations, but couldn’t prove that low folate causes poor sperm quality. Second, the study included only healthy young men (18-40 years), so we don’t know if these findings apply to older men or those with existing health problems. Third, only a small percentage of men had severe folate deficiency, making it hard to study the effects of truly low folate. Fourth, the study was conducted in one location, which may limit how broadly the results apply to different populations. Finally, while the genetic findings are interesting, they need to be confirmed in larger studies before doctors might use genetic testing to predict fertility problems.
The Bottom Line
Moderate confidence: Men concerned about fertility should ensure adequate folate intake through diet (leafy greens, legumes, fortified grains) or consider a multivitamin containing folate. Low confidence: Genetic testing for MTHFD1 variants is not yet recommended for routine fertility assessment, but men with a family history of fertility problems might discuss this with a fertility specialist. These recommendations apply primarily to healthy men aged 18-40; older men or those with health conditions should consult their doctor.
Young, healthy men concerned about fertility or planning to have children should pay attention to folate intake. Men with a family history of fertility problems may find this research particularly relevant. This research is less immediately applicable to men over 40, those with diagnosed fertility problems, or those taking medications that affect folate metabolism—these groups should consult a fertility specialist. Women planning pregnancy should also ensure adequate folate intake, though this study focused on men.
Folate status can improve within weeks of increasing intake through diet or supplements. However, sperm production takes about 74 days from start to finish, so improvements in sperm quality from better folate status would likely take 2-3 months to become apparent. Genetic factors can’t be changed, but understanding your genetic status might help guide personalized nutrition strategies.
Frequently Asked Questions
Does low folate affect male fertility and sperm quality?
Research shows low folate is associated with reduced sperm quality in healthy men. A 2026 study of 197 men found that genetic variations affecting folate use were linked to 7.7% lower sperm movement and 4.4 times higher odds of abnormal sperm patterns, suggesting folate plays an important role in male reproductive health.
What foods have folate to improve sperm health?
Folate-rich foods include leafy greens (spinach, kale), legumes (lentils, chickpeas, black beans), asparagus, broccoli, and fortified grains. Adult men need 400 micrograms daily. Including these foods regularly may support sperm quality, though improvements typically take 2-3 months since sperm production takes about 74 days.
Can genetic testing predict fertility problems in men?
Genetic testing for folate-metabolism variants like MTHFD1 is not yet recommended for routine fertility screening. While this 2026 study found associations between certain genetic variants and sperm quality, more research is needed before genetic testing becomes standard practice for assessing male fertility.
How much folate should men take for better sperm?
The recommended dietary allowance for adult men is 400 micrograms of folate daily. Most healthy men can meet this through diet alone. If considering supplements, consult a doctor first, especially if taking other medications, as excessive folate can interact with certain drugs.
How long does it take to see improvements in sperm quality from better nutrition?
Sperm production takes approximately 74 days from start to finish. Improvements in sperm quality from better folate intake would likely become apparent after 2-3 months of consistent adequate intake. Follow-up sperm analysis at this timeframe would be needed to measure actual improvements.
Want to Apply This Research?
- Track daily folate intake in micrograms (target: 400 mcg for adult men) by logging foods like spinach, broccoli, lentils, and fortified cereals. Monitor this weekly to identify patterns and ensure consistent adequate intake.
- Add one folate-rich food to your daily routine: a handful of spinach in smoothies, a side of steamed broccoli at dinner, or a serving of beans in lunch. Use the app to set a daily reminder and track completion for 12 weeks to assess any changes in energy or health markers.
- Create a 12-week folate optimization plan: weeks 1-4 establish baseline intake tracking, weeks 5-8 increase folate-rich foods, weeks 9-12 maintain and monitor consistency. If fertility is a concern, consider follow-up sperm analysis at 3 months to assess any improvements.
This research is observational and cannot prove that low folate causes poor sperm quality—only that they are associated. These findings apply specifically to healthy men aged 18-40 and may not apply to older men, those with existing health conditions, or those taking medications affecting folate metabolism. Genetic testing for fertility assessment is not yet standard medical practice. If you have concerns about fertility, sperm quality, or folate status, consult a healthcare provider or fertility specialist for personalized medical advice. This article is for educational purposes and should not replace professional medical guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.