Lab Library

Fertility -- Men

Fertility -- Men is a lab panel for trying to conceive, or a pre-conception baseline on the male side. It covers 9 markers. This page explains what each one measures, what it does NOT measure, and which nutrients are known to move it.

The markers, and what they actually tell you

Each marker below carries its technical name, what it measures in plain language, the limits of what it can tell you, and the nutrients known to move it. Where a framework and mainstream practice disagree, both views are shown rather than one being hidden.

Total & Free Testosterone

Cellular Six: Sense

This marker sits in Sense -- signals being produced, detected and acted on.

The primary male androgen; should be drawn in the morning (levels are highest then and fall through the day) and, ideally, confirmed on a second morning sample before acting on a low result.

Typical range: Conventional: total testosterone roughly 300-1000 ng/dL (lab/assay-dependent), free testosterone roughly 5-21 ng/dL (or calculated from total T + SHBG + albumin). The main urology guideline (AUA) sets a working diagnostic threshold around <300 ng/dL *with symptoms* for treatment consideration -- it does not endorse a higher "optimal" target. Functional-medicine opinion often favors the upper half of the range (600-900 ng/dL); this is not an established consensus target.

Nutrients that move it

  • Vitamin Dsolid -- two well-designed RCTs (the Graz Vitamin D&TT-RCT) found vitamin D3 supplementation (20,000 IU/week for 12 weeks) had no significant effect on total testosterone in men with either normal or low baseline levels -- directly contradicting the popular claim that correcting vitamin D raises testosterone, despite observational studies linking low vitamin D to low testosterone (correlation, not causation). (cite: Pilz S et al., Journal of Clinical Endocrinology & Metabolism, 2017-2018, PMID 28938446; PMC6842386)
  • Zincemerging -- a systematic review found zinc restriction lowered testosterone in normal men over ~20 weeks, and repletion in marginally zinc-deficient older men raised it back; in men with already-adequate zinc status, extra supplementation showed no further testosterone benefit -- real effect, but only in deficiency, not a general booster. (cite: systematic review, Journal of Trace Elements in Medicine and Biology, 2023)
  • Ashwagandha (Withania somnifera)emerging -- in a small RCT of oligospermic (low sperm count) men, ashwagandha root extract (675 mg/day for 90 days) raised serum testosterone by 17% and LH by 34% alongside sperm-parameter improvements. But a systematic review of herbs and testosterone in men found the overall RCT literature too heterogeneous (different extracts, doses from 240-675 mg/day, mixed populations) for firm conclusions, and at least one more recent 8-week RCT in men found no significant testosterone difference versus placebo. Net read: plausible and studied, but not a reliable, dose-predictable effect. (cite: Ambiye VR et al., Evidence-Based Complementary and Alternative Medicine, 2013, PMC3863556; systematic review of herbs and testosterone in men, Advances in Nutrition, 2022)
  • Boroncontested -- same thin evidence base as in the SHBG entry below; popular in supplement marketing, weak human trial support for reliably raising free testosterone.
  • Most commercial "testosterone booster" ingredients (tribulus terrestris, fenugreek, D-aspartic acid, etc.)contested -- the honest picture: most of these lack rigorous, independently replicated RCT evidence of raising serum testosterone in men with normal-range baseline levels. A few (fenugreek) have small positive trials, but effect sizes are modest and a disproportionate share of positive trials are industry-funded. Be candid with clients that "test booster" supplement claims mostly outrun the evidence.

Food first: Healthy body weight (obesity lowers testosterone both through increased peripheral aromatization to estradiol and through lower SHBG), resistance exercise, adequate sleep, and avoiding chronic caloric restriction or overtraining are more consistently evidence-backed than any single supplement.

When to see someone: This is a sourcing problem more than a nutrient problem. Most commercial "testosterone booster" blends -- tribulus, fenugreek, D-aspartic acid -- do not hold up in trials, and the FDA has documented cases of such products containing **undisclosed anabolic steroids or prescription hormones**. That is a manufacturing and verification failure, and it is precisely why a product needs a traceable manufacturing record and published efficacy behind it before it is worth taking. Separately, a genuinely low result is worth a workup including LH and FSH, since those distinguish a testicular cause from a pituitary one -- and that changes what actually helps.

Read the studies on Total & Free Testosterone

LH & FSH

Pituitary gonadotropins; LH stimulates testicular Leydig cells to produce testosterone, FSH stimulates Sertoli cells and drives spermatogenesis. Together with testosterone, they distinguish primary (testicular) from secondary (pituitary/hypothalamic) hypogonadism.

Typical range: Conventional: LH roughly 1.5-9.3 mIU/mL, FSH roughly 1.5-12.4 mIU/mL (both assay-dependent). A high FSH with low testosterone points to primary testicular failure; low/normal LH and FSH with low testosterone points to a pituitary/hypothalamic cause.

Nutrients that move it

  • Adequate energy availabilitysolid -- as in women, chronic under-fueling relative to training load (common in some endurance athletes) can suppress the hypothalamic-pituitary-gonadal axis, lowering LH, FSH, and testosterone together; correcting the energy deficit restores normal signaling.

Food first: Adequate total energy intake for high-training-volume men; beyond that, there's no dietary way to move LH/FSH in a man with a normal axis.

When to see someone: An elevated FSH with low testosterone needs medical workup for primary testicular failure -- not a nutrition-first approach.

Read the studies on LH & FSH

Estradiol

In men, estradiol is produced mainly via aromatization of testosterone in adipose tissue; elevated levels (common with excess body fat) can suppress the hypothalamic-pituitary-gonadal axis and lower sperm counts, while very low estradiol (e.g., from aromatase-inhibitor misuse) impairs bone health and libido.

Typical range: Conventional: roughly 10-40 pg/mL (assay-dependent; sensitive/mass-spec assays may report differently than standard immunoassays).

Nutrients that move it

  • Weight managementsolid -- adipose tissue aromatase converts testosterone to estradiol, so excess body fat is the most common driver of an unfavorable testosterone-to-estradiol ratio in men; weight loss reliably improves it.
  • Zinc -- proposed aromatase-modulating role is mostly theoretical; weak direct human trial evidence for changing serum estradiol specifically.

Food first: Weight loss if overweight is the most evidence-backed lever; limiting excessive alcohol intake also helps (alcohol impairs hepatic estrogen clearance).

When to see someone: Aromatase-inhibiting drugs and supplements taken to push oestradiol down can over-suppress it, and the cost lands on bone density and libido. There is a floor here as well as a ceiling.

Read the studies on Estradiol

Sex Hormone-Binding Globulin (SHBG)

Cellular Six: Sense

This marker sits in Sense -- signals being produced, detected and acted on.

A liver-made protein that binds testosterone and estradiol, controlling how much circulates free and biologically active.

Typical range: Conventional: roughly 10-57 nmol/L in men (lab/assay-dependent).

Nutrients that move it

  • Boron** and **cruciferous vegetables/DIMcontested -- see `Function-Health-Hyman.md` SHBG entry; the same thin evidence base applies to men.

Food first: Weight management (higher body fat is associated with lower SHBG in men), adequate but not excessive protein intake.

When to see someone: Treat boron/DIM supplement marketing claims skeptically -- plausible biochemistry, weak outcome evidence.

Read the studies on Sex Hormone-Binding Globulin (SHBG)

Prolactin

A pituitary hormone; in men, meaningful elevation suppresses testosterone and libido and, if markedly high, suggests a prolactinoma or medication effect.

Typical range: Conventional: roughly 4-15.2 ng/mL (assay-dependent).

Food first: General stress management and adequate sleep; no reliable dietary lever exists for a truly elevated level.

When to see someone: A significantly elevated prolactin in a man needs medical workup, including pituitary imaging if very high -- this is not a nutrition-first situation.

Read the studies on Prolactin

Sperm Concentration, Total Count & Semen Volume

How many sperm are present and in what volume of ejaculate -- the most basic quantitative fertility screen.

Typical range: WHO 6th edition (2021) lower reference limits (5th percentile of a fertile reference population): semen volume >=1.4 mL, sperm concentration >=16 million/mL, total sperm number >=39 million per ejaculate. (cite: World Health Organization, WHO Laboratory Manual for the Examination and Processing of Human Semen, 6th edition, 2021)

Nutrients that move it

  • Zincemerging -- a meta-analysis of 20 studies (2,600 infertile cases vs. 867 controls) found seminal plasma zinc significantly lower in infertile men, and supplementation trials show increases in semen volume, motility, and normal morphology; the effect is most consistent when baseline zinc status is genuinely low. (cite: meta-analysis, Scientific Reports, 2016, PMC4773819)
  • Folic acid + zinc combinedsolid -- the FAZST trial, the largest and most rigorously designed RCT in this space to date (2,370 men at 4 US fertility centers, NIH-funded, double-blind, placebo-controlled), found daily folic acid (5 mg) plus zinc (30 mg) for up to 6 months produced **no improvement** in sperm concentration, motility, morphology, semen volume, or live birth rate compared with placebo. This directly contradicts decades of smaller, positive folic-acid/zinc trials and the "fertility multivitamin" marketing built on that older evidence -- it's a textbook example of a well-powered trial overturning a popular supplement claim. (cite: Schisterman EF et al., JAMA, 2020)
  • CoQ10emerging -- a meta-analysis of 3 RCTs (149 vs. 147 men) found CoQ10 supplementation significantly increased sperm concentration and total motility (RR 4.50 for motility), but no included trial reported live birth or pregnancy rate -- so this is a semen-parameter benefit only, not proven to translate into more babies. (cite: Lafuente R et al., Journal of Assisted Reproduction and Genetics, 2013, PMID 23912751)
  • L-carnitine / acetyl-L-carnitineemerging -- a systematic review of 8 RCTs found carnitine supplementation significantly improved total and progressive motility and morphology, without a clear effect on concentration; a network meta-analysis ranked L-carnitine first among antioxidants for motility and morphology. An early placebo-controlled RCT (60 men, 6 months) found improved motility and 4 spontaneous pregnancies in the treatment group. As with CoQ10, improvements in semen parameters have not been proven in large trials to reliably raise live-birth rates. (cite: Lenzi A et al., Fertility and Sterility, 2004, PMID 15193480)
  • Lycopeneemerging -- one RCT in 44 oligozoospermic (low count) men (25 mg/day for 12 weeks) found increased sperm count, concentration, and motility; a separate RCT of lactolycopene (14 mg/day, 12 weeks) in 60 *healthy* young men found no change in the primary motile-sperm-concentration endpoint, though morphology and fast-progressive motility did improve. Effects look more reliable in men who start out with genuinely low counts than in men with normal-range semen parameters. (cite: Nouri M et al., Phytotherapy Research, 2019)

Food first: An overall antioxidant-rich diet, healthy body weight, limiting alcohol/smoking/cannabis (all associated with lower counts), and avoiding chronic scrotal heat exposure (frequent hot tubs/saunas, laptop directly on lap) -- the heat-exposure evidence is weaker than the others but biologically plausible and low-cost to address.

When to see someone: A single semen analysis is noisy -- sperm production takes roughly 72-90 days, so a recent fever, illness, or heat exposure can transiently tank a result. Always repeat an abnormal semen analysis before drawing conclusions, and get a urology/reproductive-endocrinology referral for severely abnormal results rather than relying on supplements alone.

Read the studies on Sperm Concentration, Total Count & Semen Volume

Sperm Motility (Total & Progressive)

The percentage of sperm that are moving (total motility) and moving in a purposeful, forward direction (progressive motility) -- the parameter most consistently linked to natural conception ability.

Typical range: WHO 6th edition (2021) lower reference limits: total motility >=42%, progressive motility >=30%.

Nutrients that move it

  • Omega-3 fatty acids (EPA/DHA)emerging -- in the EARTH prospective cohort, men's dietary omega-3 intake was associated with better semen quality parameters. Direct supplement-RCT evidence specifically for omega-3 and motility in this exact population is weaker than the observational diet data, partly because a chunk of the older idiopathic-oligoasthenoteratospermia supplement-trial literature (including omega-3 trials) comes from research groups whose work has since drawn documented integrity concerns -- see the Evidence Integrity Note below. Treat the omega-3-and-motility supplement claim as emerging/unsettled rather than proven, even though the general diet-quality association is more credible. (cite: Mínguez-Alarcón L, Chavarro JE, et al., American Journal of Obstetrics and Gynecology, 2022, PMC9308672)

Food first: Fatty fish 2-3x/week or an algae-based EPA/DHA supplement for the general omega-3 signal; otherwise the same overall pattern as the Concentration section.

When to see someone: Same repeat-testing caveat as above -- don't over-interpret a single abnormal motility result.

Read the studies on Sperm Motility (Total & Progressive)

Sperm Morphology

The percentage of normally shaped sperm by strict (Kruger) criteria. Of the three classic semen parameters, morphology correlates the least reliably with actual conception ability on its own.

Typical range: WHO 6th edition (2021) lower reference limit: >=4% normal forms by strict criteria.

Food first: Same general antioxidant-supportive dietary pattern as the Concentration section; nothing morphology-specific beyond that.

When to see someone: Don't over-interpret an isolated low morphology percentage as "the cause" of infertility -- it needs to be weighed alongside count, motility, and the female partner's workup.

Read the studies on Sperm Morphology

Sperm DNA Fragmentation (DFI)

The percentage of sperm with damaged or fragmented DNA (measured via SCSA, TUNEL, or Comet assay -- results are **not** interchangeable across these methods). Elevated fragmentation is associated with lower IVF/ICSI success and higher miscarriage risk even when standard semen parameters look normal.

Typical range: Assay-dependent; commonly cited SCSA-based bands are <15% (good), 15-30% (fair/moderate), >30% (poor), though there is no single validated clinical cutoff that applies across all assay types, and ASRM has not endorsed universal testing for this reason.

Nutrients that move it

  • Combined antioxidants (vitamin C, vitamin E, zinc, selenium, CoQ10, carnitine, lycopene, in varying combinations)emerging -- several smaller RCTs and a network meta-analysis show antioxidant supplementation can reduce DNA fragmentation index and improve some oxidative-stress markers. **However**, the largest and most authoritative synthesis -- the Cochrane systematic review of antioxidants for male subfertility (61 trials, 6,264 subfertile men) -- concluded the overall evidence is **inconclusive** for the outcomes that actually matter (live birth, clinical pregnancy), citing serious risk of bias, poor reporting, high attrition, and small/imprecise trials. An updated Cochrane review reached a similarly cautious conclusion. Improvements in DFI or other surrogate/lab markers have not been reliably shown to translate into more live births. (cite: Smits RM et al., Cochrane Database of Systematic Reviews, 2019, CD007411.pub4; de Ligny W et al., Cochrane Database of Systematic Reviews, 2022, CD007411.pub5)

Food first: Reducing broad oxidative-stress exposures -- smoking cessation, limiting heat/toxin exposure, treating a varicocele if present, moderating alcohol -- has more consistent mechanistic logic behind it than reaching for any single supplement to lower DNA fragmentation.

When to see someone: High-dose combined antioxidant supplementation is not automatically risk-free. In other contexts (e.g., cancer-prevention trials), high-dose antioxidant supplementation has paradoxically worsened outcomes -- the "antioxidant paradox" -- and there's no evidence that piling on multiple antioxidants at high doses helps a nutrient-replete man. Favor modest, targeted doses of specific nutrients over mega-dosing a combination product.

Read the studies on Sperm DNA Fragmentation (DFI)

Food first, then fill the gaps

Every marker above lists the nutrients known to move it. Build a day around them first -- the Diet Builder shows which food groups you are consistently missing, inside the way you already eat.