Supplements for Fertility: Can L-Carnitine Raise FSH and LH?
Updated: Nov 4
By Dr. Harsimranjeet Singh Bhatia, ND · Last reviewed November 2026
The short answer: For most people, raising FSH is not a helpful goal, because a high FSH early in the cycle usually signals a lower egg reserve rather than a problem to fix. Small studies suggest acetyl-L-carnitine may raise LH in women with stress related hypothalamic amenorrhea and low LH, but no supplement has been shown to correct FSH or LH in general or to improve pregnancy rates on its own.
If you have just seen your blood work and an FSH or LH value is flagged, it is natural to search for a way to bring it back into range. Many people are told about supplements that claim to balance these hormones. The honest picture is more nuanced, and understanding what these numbers actually mean can save a lot of worry and money.
What do FSH and LH do, and should you try to increase them?
FSH and LH are released by the pituitary gland and guide the ovaries through each cycle. FSH helps follicles grow, and a surge of LH triggers ovulation. Their levels change from day to day, so a single result only makes sense when you know the cycle day and look at it alongside other markers such as AMH, antral follicle count and estradiol.
A raised FSH early in the cycle is one sign of reduced ovarian reserve. The American Society for Reproductive Medicine notes that FSH varies a great deal between cycles, that a high estradiol can push FSH falsely into the normal range, and that none of these markers predict well whether a person will conceive. In other words, a higher FSH is usually not something to chase. On the other hand, FSH and LH that are both low can reflect hypothalamic amenorrhea, where stress, low energy availability or intense exercise quiet the signals from the brain. That situation calls for finding the cause, not simply adding a supplement.
Can a supplement increase LH levels?
The most studied option is acetyl-L-carnitine. In a small study of women with functional hypothalamic amenorrhea, those who started with low LH saw their LH levels and the size of their LH pulses rise over several months, while women whose LH was already normal saw no change. A later study from the same research group, combining L-carnitine and acetyl-L-carnitine, found similar changes in LH along with lower cortisol. Neither study had a placebo group, neither showed a change in FSH, and neither reported periods returning or pregnancies. So the finding is interesting but narrow, and it does not mean these supplements are a way to raise LH in general.
What is L-carnitine, and does it help egg quality?
L-carnitine helps carry fats into the mitochondria, the energy producing parts of our cells, and it has antioxidant properties. Because developing eggs are energy hungry and sensitive to oxidative stress, researchers have proposed that L-carnitine and acetyl-L-carnitine could support egg maturation and quality. A 2018 review in Reproductive Biology and Endocrinology summarized this thinking. Most of the egg quality evidence, however, comes from animal and laboratory studies, and at least one mouse study showed harm to embryos, so we do not yet have human trials showing better egg quality.
Does L-carnitine help with PCOS?
L-carnitine has been studied more in PCOS than in any other fertility setting, and the results are best described as modest and still uncertain. A 2023 meta-analysis in Clinical Endocrinology found that, compared with placebo, carnitine lowered fasting insulin and a measure of insulin resistance and led to a small drop in BMI, with no change in fasting glucose. A double blind trial in women with PCOS who were overweight or living with obesity found the same improvement in insulin resistance over twelve weeks, without changes in SHBG or cholesterol. The benefit seems to show up mainly in women carrying extra weight, with little effect in lean women. Studies disagree on blood lipids: one meta-analysis found improvements in cholesterol and triglycerides, while others found none.
The fertility results are less settled. Earlier reports of better ovulation and pregnancy rates leaned heavily on one trial in women who had not responded to clomiphene, and that trial has since been retracted. It is also among the studies cited in both meta-analyses, so their fertility findings should be read with caution: the 2023 meta-analysis reported higher ovulation and pregnancy rates with wide uncertainty, while an earlier 2022 meta-analysis of nine trials found no significant effect on ovulation or pregnancy. Most trials have been small and short, usually around three months, and none has reported live births. L-carnitine is not part of PCOS treatment guidelines and is not a replacement for lifestyle care, metformin or standard ovulation induction, but it is a reasonable topic to raise with a clinician who can weigh it against your full picture.
Is L-carnitine safe while trying to conceive?
L-carnitine is generally well tolerated, but it is not without considerations. At higher intakes it can cause nausea, diarrhea and a fishy body odour. It may blunt the action of thyroid hormone inside cells, which matters for anyone taking thyroid medication. Gut bacteria convert carnitine into a compound called TMAO that has been linked with heart disease in animal and observational research. Certain seizure medications lower carnitine levels, and caution is advised with a seizure history. Long term safety data in people trying to conceive are limited. This is why a supplement that seems simple deserves an indication, a safety and interaction review, and follow up blood work.
If your FSH or LH results have left you with questions, working with a fertility focused clinician can help you understand what they mean in the context of your full picture, and whether any supportive care is appropriate.
Disclaimer: This article is for educational purposes only and is not medical advice. It is not intended to diagnose, treat, or prevent any condition. Individual circumstances vary, and decisions about your care should be made with your own healthcare team. If you are trying to conceive or are currently in treatment, please speak with your physician or a licensed naturopathic doctor before making changes.
References
Practice Committee of the American Society for Reproductive Medicine. Testing and interpreting measures of ovarian reserve: a committee opinion. Fertility and Sterility. 2020;114(6):1151-1157. doi:10.1016/j.fertnstert.2020.09.134
Genazzani AD, Lanzoni C, Ricchieri F, Santagni S, Rattighieri E, Chierchia E, et al. Acetyl-L-carnitine (ALC) administration positively affects reproductive axis in hypogonadotropic women with functional hypothalamic amenorrhea. Journal of Endocrinological Investigation. 2011;34(4):287-291. doi:10.1007/BF03347087
Genazzani AD, Despini G, Czyzyk A, Podfigurna A, Simoncini T, Meczekalski B. Modulatory effects of L-carnitine plus L-acetyl-carnitine on neuroendocrine control of hypothalamic functions in functional hypothalamic amenorrhea (FHA). Gynecological Endocrinology. 2017;33(12):963-967. doi:10.1080/09513590.2017.1332587
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Gong Y, Jiang T, He H, Wang Y, Wu GL, Shi Y, et al. Effects of carnitine on glucose and lipid metabolic profiles and fertility outcomes in women with polycystic ovary syndrome: a systematic review and meta-analysis. Clinical Endocrinology. 2023;98(5):682-691. doi:10.1111/cen.14885
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Liao D, Liu X, Yuan X, Feng P, Ouyang Z, Liu Y, et al. Clinical evidence of the effects of carnitine supplementation on body weight, glycemic control and serum lipids in women with polycystic ovary syndrome: a systematic review and meta-analysis. Gynecological Endocrinology. 2022;38(2):110-115. doi:10.1080/09513590.2021.1988559
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Benvenga S, Ruggeri RM, Russo A, Lapa D, Campenni A, Trimarchi F. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. Journal of Clinical Endocrinology and Metabolism. 2001;86(8):3579-3594. doi:10.1210/jcem.86.8.7747
National Institutes of Health, Office of Dietary Supplements. Carnitine: fact sheet for health professionals. ods.od.nih.gov
About the author
Dr. Harsimranjeet Singh Bhatia, ND. Dr. Bhatia is an award winning naturopathic doctor in Ottawa whose practice has focused exclusively on fertility and reproductive health for over ten years. He received the Ontario Association of Naturopathic Doctors Emerging Leader award in 2026 and was named Naturopath of the Year by Faces Magazine Ottawa four years in a row. He has presented grand rounds to physicians at The Ottawa Hospital and collaborates with fertility clinics, supporting individuals and couples across Ontario and Quebec who are trying to conceive naturally or alongside IUI and IVF. His care centres on evidence informed support for egg quality, sperm health, hormonal balance, implantation and early pregnancy, always coordinated with your medical team.
