A new study suggests that antioxidants do not improve a woman's chances of conceiving as previously suggested, according to researchers from the University of Auckland, New Zealand.
The study, published in The Cochrane Library, found that women who take oral antioxidants are no more likely to conceive and that there was "limited information" about potential harmful effects.
Other research has suggested that antioxidants could boost fertility within men. A previous study, also from the University of Auckland, showed that partners of men who take antioxidants may be more likely to become pregnant.
The study authors say that around 25% of people planning to have a baby experience trouble conceiving and many take dietary supplements, such as antioxidants, to try and improve their chances of becoming pregnant.
However, the researchers say that there is no sufficient evidence that this is the case, and they add that many of the antioxidants taken are unregulated, with little evidence on their safety and effects.
The researchers conducted an analysis of data from 28 trials involving 3,548 women who were undergoing fertility treatment. The duration of the fertility treatment ranged from 12 days to 2 years, and the age of the women ranged between 18 to 42.
The analysis of the trials showed that a variety of antioxidants were used in the fertility treatment process of some women. These included individual doses or combinations of:
- Multiple micronutrients and Fertility Blend
- Vitamin E
- Vitamin C
- Vitamin D and Calcium
- Omega-3 polyunsaturated fatty acids.
Results of the analysis showed that compared to women taking placebos or being given standard treatments including folic acid, there was no significant increase of women taking antioxidants becoming pregnant.
When it comes to potential side effects of women taking antioxidants as a part of fertility treatment, previous research has suggested that antioxidants could be the cause of fertility problems in females.
However, the results of this most recent study show that women taking antioxidants experience no more adverse affects compared to women who undergo standard treatment or those taking placebos. They add that only 14 of the trials showed adverse effects, such as ectopic pregnancy and miscarriage.
In summarizing the results, the study authors say:
"Antioxidants were not associated with an increased live birth rate or clinical pregnancy rate.
Variation in the types of antioxidants given meant that we could not assess whether one antioxidant was better than another. There did not appear to be any association of antioxidants with adverse effects for women, but data for these outcomes were limited."
The researchers note that the quality of evidence in the trials was "very low to low" due to a poor reporting outcome and the small number of studies included.