The Most Extensive Study Ever on Nutrients & Male Fertility

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Sperm quality and count are both important causes of male infertility, but both have been plummeting over the past several years. In our book Sex & Fertility: Natural Solutions, we discuss research from the 1990's that was already showing that sperm count had dropped by 40% in only half a century. Since then, the news has only gotten worse: a recent meta-analysis of 185 studies found drops of 52.4% (1).

Now, the most extensive and systematic review of randomized studies has been conducted on the effect of nutrients on sperm quality and male fertility (2). The review analyzed 28 studies that included 2,900 people. It found that several supplements-specifically omega-3 essential fatty acids, coenzyme Q10, selenium, zinc and carnitine- -benefit sperm quality, quantity and male fertility. The goal in improving fertility is increasing sperm count, sperm quality and sperm motility.


The review found that omega-3 essential fatty acids benefit male fertility in four ways: sperm quantity, concentration, morphology and motility. This means that omega-3's, like those found in flaxseeds and flaxseed oil, improve the number and shape of sperm as well as the important ability to move.


The review also found that coenzyme Q10 helps fertility in all four ways: sperm quantity, concentration, morphology and motility. Even amounts as low as 10mg a day of CoQ10 can increase sperm count and motility (3). When 200mg of CoQ10 was given to infertile men, they had significantly greater improvements in sperm count, motility and morphology than men given a placebo (4).


The antioxidant mineral selenium was found by the review to help infertility in three ways: it improves sperm concentration, morphology and mobility. Selenium deficiency has previously been linked to reduced sperm counts and sterility. A double-blind study of infertile men with reduced sperm motility found that selenium does increase motility. When men took selenium, 11% of the couples in the study conceived compared to 0% of those who got a placebo (5).


The review found that zinc helped infertility by increasing sperm concentration and motility. Zinc is one of the most crucial nutrients for male fertility. Low zinc can cause infertility because it causes low testosterone, poor sperm motility (6) and low sperm levels (7).

Zinc can improve sperm count (8,9) and, according to many, but not all, studies, sperm motility (10,11). Zinc can also improve the physical characteristics of sperm (12). Putting all three of count, motility and shape together, one placebo-controlled study of 100 men with low sperm motility found that 57mg of zinc twice a day for three months led to significant improvements in sperm count, motility and quality (13).

A study of 37 men who had been infertile for at least five years found that those who had low testosterone levels experienced a significant increase in both testosterone levels and sperm count when given 60mg of zinc for 45-50 days. But the real proof that zinc passed the test is that, even though the study was so short, nine of the 22 men who had low testosterone conceived with their partners (14).


The review found that the amino acid L-carnitine can help fertility by improving sperm motility and morphology.

L-carnitine seems to be crucial for sperm to mature (15). More carnitine means more sperm and more mobile sperm (16). The research is especially impressive for motility. Not having enough carnitine leads to poor sperm development, function and motility.

Sperm quality improves with as little as 1g of carnitine a day. With improvement in quality comes improvement in motility: 2g of carnitine taken twice a day increases the percentage of mobile sperm from 25.5% to 46.7%. In an impressive study, 47 men who averaged less than 30% mobile sperm-50% or more is normal-were given 3g of carnitine a day for three months. By the end of the study, an incredible 80% had motility levels close to normal. At least as important, the percentage of sperm that moved forward in a rapid linear motion increased: these are the sperm that are most likely to succeed. Carnitine supplementation also increased sperm count (17). A second study has also found an increase in these "most likely to succeed sperm". When 100 men with a low percentage of mobile sperm were given 3g of carnitine a day for four months, the sperm with rapid linear motion increased from 10.8% to 18%. Overall motility increased from 26.9% to 37.7% and the sperms' velocity significantly increased. The carnitine also led to significantly greater sperm count (18). Other research has also found increased count and motility with 3g of carnitine a day. A combination of 2g of L-carnitine and 1g of L-acetyl-carnitine led to increased count, motility and morphology (19).

So, can all of this add up to increased pregnancies? Yes. When researchers gave 4g of acetylcarnitine, they found not only significant increases in the all-important percentage of sperm with rapid linear motion, but also that 35% of the female partners became pregnant (20).

When L-carnitine was combined with CoQ10 in men with low sperm count, sperm motility improved significantly and pregnancy went up from 6.8% in the control group to 30% in the supplement group (21).

Other Nutrients that Help

Other nutrients not discussed in the new review may also help. When infertile men were given 1g of vitamin C, after only one week, their sperm counts went up by an incredible 140%. After three weeks, their sperm count was still climbing. At the start of the study, many of the men had agglutinated sperm (25% of their sperm was agglutinated: enough to cause infertility), but after three weeks, only 11% of their sperm was agglutinated. After sixty days, all of the men had conceived children with their wives: none of the men in the placebo group had (22). Sperm are agglutinated when they clump together. Agglutination reduces your chance of fertility, but vitamin C reduces agglutination (23,24).

Other antioxidants also help. When 200mcg of selenium was combined with 400IU vitamin E in men with low sperm motility, 52.6% of men improved their sperm mobility, morphology or both. 10.8% of their partners became pregnant (25).

The most important study of male infertility and antioxidants yet is a Cochrane review of 34 controlled studies of 2,876 couples who were having difficulties becoming pregnant because the male had either low sperm count or low sperm motility. The results showed that when the men were given antioxidants, the couples were more than four times more likely to conceive and nearly five times more likely to have a successful delivery. Both improvements were statistically significant. Vitamin E and, not surprisingly, zinc and L-carnitine may have been the most effective (26).

Supplementing B12 increases sperm count in 54-60% of men and sperm motility in 50% (27,28,29).

L-arginine may also help. Arginine deficient diets cause sperm counts to plummet (30). Taking arginine improves sperm count and motility in 74% of men (31). Several preliminary studies show that arginine improves sperm count, quality and motility as well as fertility (32,33,34,35). If your sperm count is still over 10 million per milliliter, try 4g a day of arginine; if it is under 10 million, it probably won't help.

And finally, preliminary research suggests that S-adenosyl-L-methionine (SAMe) may help sperm motility (36).

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