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L-arginine: A supplement for thin lining and low sperm count

L-arginine: A supplement for thin lining and low sperm count

by Margaret Eich, MS, RDN

L-arginine is a supplement that may be helpful for a few specific situations in female and male fertility. First, let’s go over some basic information about L-arginine. L-arginine is an amino acid that our body makes and is naturally found in foods containing protein. Amino acids are the building blocks of proteins that make up structural components of our body like muscle and organs, act as enzymes to catalyze vital reactions in the body, and allow cells to communicate with each other to perform vital body functions.

Role in Female Fertility

For women with a thin uterine lining, L-arginine may help improve the thickness of the lining. Adequate thickness of the endometrium, or uterine lining, is important for supporting a pregnancy. Women with a thin lining tend to have low pregnancy rates. A thin lining is defined as a lining of less than 8 millimeters (mm). A thin lining may be due to reduced blood flow through the uterine arteries. L-arginine is a precursor to nitric oxide, which increases blood flow by increasing the dilation of the arteries. L-arginine treatment has been shown to increase the thickness of the endometrial lining. In 6 of 9 patients with a thin lining who took L-arginine, the endometrial lining increased to greater than 8 mm. 1

Research also suggests that L-arginine may be helpful for patients who are poor responders in an IVF cycle. Poor responders are women who respond poorly to ovarian stimulation medication in that they tend to have few eggs to retrieve or IVF cycles are cancelled. In a study of 34 patients who were poor responders going through IVF, treatment with L-arginine resulted in a lower frequency of cancelled cycles and an increase in the number of eggs retrieved. 2 Later research in patients with tubal infertility showed that L-arginine treatment resulted in fewer good quality embryos and lower pregnancy rates, suggesting that L-arginine may be detrimental for women who are normal responders. 3

Role in Male Fertility

L-arginine has been studied in combination with other supplements like pycnogenol and found to be helpful in increasing sperm concentration (count). In one study, sperm concentration increased after 1-2 months of daily treatment with L-arginine. 4-5 It’s thought to work through increased nitric oxide production improving circulation.


L-arginine is contraindicated if you struggle with low blood pressure. Arginine can also trigger a herpes outbreak, so L-arginine may not be the right choice if you have herpes. As mentioned above, L-arginine may also be detrimental in women who are not poor responders. Remember to discuss all supplement regimens with your physician.

Bottom Line

The bottom line is that L-arginine may be helpful for women with a thin lining or who have a poor response to ovarian stimulation medications and for men with low sperm count/concentration.


1. Takasaki A, Tamura H, Miwa E, et al. Endometrial growth and uterine blood flow: a pilot study for improving endometrial thickness in patients with a thin endometrium. Fertil Steril. 2010;93(6):1851-1858.

2. Battaglia C, Salvatori M, Maxia N, et al. Adjuvant L-arginine treatment for in-vitro fertilization in poor responder patients. Hum Reprod. 1999;14(7):1690-1697.

3. Battaglia C, Regnani G, Marsella T, et al. Adjuvant L-arginine treatment in controlled ovarian hyperstimulation: a double-blind, randomized study. Hum Reprod. 2002;17(3):659-665.

4. Stanislavov R, Nikolova V, Rohdewald. Improvement of seminal parameters with Prelox: a randomized, double-blind, placebo-controlled, cross-over trial. Photother Res. 2009;23(3):297-302.

5. Stansilavov R, Rohdewald P. Sperm quality in men is improved by supplement with a combination of L-arginine, L-citrullin, roburins, and Pycnogenol®. Minerva Urol Nefrol. 2014;66(4):217-223.