Vitamin C Found to Increase Progesterone Levels and Correct Luteal Phase Defect
Menstrual Cycles

Richard J. Fehring
Reprint from Current Medical Research
Vol 15, No 1-2, Winter/Spring 2004
Washington, DC
Reproduced with Permission

Up to 10% of women with primary or secondary infertility and up to 35% of women with repeated or habitual (miscarriages) have a luteal phase defect. The cause of the infertility and pregnancy loss is thought to be a result of an inadequate maturation and development of the endometrium. The reason for the retarded development of the endometrium is thought to be in part due to inadequate levels of progesterone production by the corpus luteum. A reason for poor progesterone production could be due to oxidative stress, free radicals, and high levels of lipoperoxide. Ascorbic acid (Vitamin C) and other anti-oxidative substances helps to prevent oxidative stress and the production of free radicals that interfere with progesterone production. Furthermore, low plasma levels of ascorbic acid (i.e., Vitamin C) have been found in women who habitually miscarry. Ascorbic acid deficiency produces ovarian atrophy and extensive follicular atresia.

Japanese researchers (from Sapporo Medical University School of Medicine) recently tested the effects of Vitamin C on the serum progesterone levels and pregnancy rates of women who have documented luteal phase defects.1 One hundred fifty patients with a luteal phase defect were randomly assigned to either a control group with no treatment or daily vitamin C (750 mg). The luteal phase defect was defined as having two consecutive menstrual cycles with serum progesterone levels (taken three separate days during the mid-luteal phase) of less than 10 ng/mL. Subjects in the treatment group started daily vitamin C on the first day of the third cycle until pregnancy was confirmed or 6 months after the study was started. All subjects had serum progesterone levels taken at mid-cycle until pregnancy was confirmed or 6 months had lapsed. There were 76 patients in the vitamin C group and 46 in the control group. Twenty-eight patients withdrew from the control group when they found out they were not to be treated.

Prior to the initiation of treatment (i.e., at the first and second cycles) there was no sign)ficant difference in the mean mid-cycle serum progesterone levels. After the first cycle of treatment, serum progesterone levels were sign)ficantly elevated in the treatment group but not in the control group. Ten (22%) of the control group subjects and 40 (53%) of the treatment group subjects had mid-cycle serum progesterone levels that increased to at least 10 ng/ mL. Nineteen of the treatment group (25%) and 5 subjects (11%) in the control group had a clinically confirmed pregnancy. There was no difference in the miscarriage rate with 16% in the vitamin C group and 20% in the control group. Based on these findings, the researchers concluded that vitamin C supplementation is an effective treatment for some patients with luteal phase defects.


The findings from this small preliminary study are encouraging. The use of a vitamin C supplementation to help treat low progesterone levels and luteal defects would be easy and inexpensive. However, because of the small number of subjects and the fact that 28 patients withdrew from the control group places some hesitancy on the findings. The Japanese researchers did not show a statistically significant difference in the mean serum progesterone levels between the two groups (even though there was a large mean post treatment difference in progesterone levels, i.e., 104 ng / mL for the control group and 138.7 ng / mL for the treatment group). The lack of statistical significance is probably a reflection of the relatively small number of subjects. A better design would be to have a double blind study, i.e., a study in which the subjects and the researchers did not know which group of subjects were getting the treatment (i.e., the control group would receive a placebo). A double blind study would preventbias on the part of the researchers and would also help prevent subjects from leaving the study when they find out that they are not receiving the treatment.


1 Henmi, H., Endo, T., Kitaiima, Y. et al. Effects of ascorbic acid supplementation on serum progesterone levels in patients with a luteal phase defect. Fertility and Sterility. 2002;80:459-461. [Back]