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While a number of studies have started to investigate the role of antioxidants in human fertility, we don’t have clear answers yet – although things certainly look promising:
Three recent studies
In a recent study, researchers did what is called a meta-analysis of 23 other studies to see if they could identify any benefits from the use of antioxidants in infertile men. They found that the levels of protective antioxidants were lower in male subjects who were unable to achieve fertilisation, compared to control subjects who were not infertile.
In addition, the levels of reactive oxygen species (harmful products of oxidative stress) were directly linked to infertility.
In a second study, 30 men who were part of couples that had been diagnosed as infertile were treated with placebo (dummy treatment) or astaxanthin (a carotenoid with very powerful antioxidant properties) for 3 months.
After 3 months of treatment with astaxanthin, the pregnancy rates increased from 10% in the infertile controls who received no antioxidants to approximately 55% in the previously infertile couples where the male partner received antioxidant treatment.
Finally, a study among women who suffered from endometriosis (a condition linked to female infertility) found that those women who had lower reactive oxygen species levels and higher levels of protective antioxidants were much more likely to fall pregnant.
The role of antioxidants in conception
The reproductive process in men (i.e. the production of millions of sperm cells) and women (i.e. the production of an egg cell) involves a great deal of oxidative energy which in turn generates high levels of reactive oxygen species (which can be likened to harmful 'waste products').
To combat the potentially harmful effects of the reactive oxygen species, the bodies of human males and females use a number of antioxidant defence systems, namely vitamins A, C, E, coenzyme Q10, glutathione reductase and superoxide dismutase (vitamins and enzymes).
In view of this and the benefits obtained in veterinary medicine with antioxidants, it would seem logical that human infertility may also be linked to low levels of antioxidants and that supplementing with antioxidants could improve fertility.
The authors of the Arbor Nutrition Updates (2007) also did a literature search to identify studies using antioxidant supplements. They found 28 such studies, representing more than 1700 subjects. Most of the studies were concerned with male infertility and sperm health.
It’s encouraging that up to 75% of these studies found that supplementing with antioxidants improved fertility.
In the above-mentioned studies, the most popular antioxidant supplements were vitamins C and E, as well as selenium and zinc. Supplementation with carnitine, coenzyme Q10 and glutathione reductase also produced positive results.
Should infertile couples take supplements?
In view of these positive findings, it would seem sensible for infertile couples (or at least the partner who has been identified as infertile) to use various supplements to improve the chance of pregnancy.
However, until more clarity about the correct doses and combinations of supplements is obtained, it’s difficult to recommend that all infertile individuals should take nutrient supplements.
There may also be risks associated with taking certain supplements.
For example, high intakes of supplemental vitamin A are not recommended when you’re trying to fall pregnant because of the risk of damage to the baby. If this is the case, it’s safer to get vitamin A from a diet rich in beta-carotene, which is abundantly found in dark yellow and dark green fruits and vegetables.
Food sources of antioxidants
At this stage, it’s probably safer to follow a well-balanced diet that’s rich in protective antioxidants than to take vitamin and mineral supplements in large doses.
The following foods are rich sources of the antioxidants that appear to improve fertility:
a) Vitamin A or beta-carotene
Liver, eggs, fatty fish, carrots, butternut, sweet potato, broccoli, spinach, dark green lettuce leaves, spanspek, mangoes, pawpaw, orange juice, apricots and yellow peaches.
b) Vitamin E
Wheat germ oil, sunflower, maize, olive and canola oils, almonds and avocado.
c) Vitamin C
Citrus fruit (oranges, lemons, grapefruit, naartjies), guavas, berries (especially cranberries), spanspek, mangoes, pawpaw; tomatoes, broccoli, Brussels sprouts, cabbage, spinach, sweet peppers and chilli peppers.
d) Zinc
Oysters, wheat germ, lean meat, liver, poultry, Ricotta cheese, pecan nuts, peanuts and seafood.
e) Selenium
Brazil nuts, fish and other seafood, wheat germ, molasses, sunflower seeds, eggs and milk.
- (Dr I.V. van Heerden, registered dietician
29 October 2007
References:
(Arbor Clinical Nutrition Updates, 2007. Antioxidants and fertility. Issue 276, April 2007.)
