Particularly overweight men often suffer from poor sperm quality and consequently from fertility problems. This often leads to frustration and tension with their partner regarding their desire to conceive. Could the intake of probiotics help here?
Probiotics for better sperm quality and fertility
Male infertility is responsible for the unfulfilled desire to have children in 50 percent of all involuntarily childless couples. Overweight men are particularly often affected by infertility due to poor sperm quality. It is assumed that it is, among other things, a testosterone deficiency that worsens sperm quality in overweight men. In general, the more overweight a man is, the fewer sperm can be counted.
Previous studies have shown that probiotics have a significant positive effect on fertility in women. The probiotic bacteria can lower the vaginal pH, colonise the vaginal flora with more lactic acid bacteria and lead to higher fertility!
Can probiotics affect male fertility?
However, how the intake of probiotics could affect male fertility was unknown until now. In 2017, researchers investigated how the intake of Lactobacillus rhamnosus (a lactic acid bacterium) affected sperm quality, levels of hormones crucial for reproduction and fat metabolism. L. rhamnosus is considered a probiotic that can have a beneficial effect on weight, i.e. it can contribute to you losing weight. And since simply achieving a lower weight has a positive effect on fertility, it was hoped that the lactic acid bacterium would also have a significant effect on the sperm quality of overweight test subjects.
Probiotics to regulate weight
The test was not performed with males, but with mice that were overweight due to a high-fat diet (60% fat). Normal-weight mice fed a conventional mouse diet served as the control group. In each group, from the 4th week onwards, some of the animals (up to the 8th week) were now given a probiotic made from different L. rhamnosus strains every day. Initially, it was observed that the administration of the probiotic prevented further weight gain. Also, the weight of the testicles in the overweight group increased when the subjects received probiotics, while in the normal-weight group everything remained the same in this respect – whether they had received probiotics or not, a sign that probiotics apparently only intervene in a regulating way, i.e. when it is necessary.
Probiotics make the sperm count rise again
The overweight subjects who did not take probiotics had the lowest sperm count. In the overweight subjects who took probiotics, on the other hand, not only did the number of motile sperm increase, but also their speed and motility. In addition, the number of immobile sperm decreased. Similarly, the testosterone, FSH and LH levels increased after taking probiotics – in both groups, i.e. in the normal-weight and overweight animals. Cholesterol levels, on the other hand, decreased. LH (luteinising hormone) stimulates the formation of testosterone in the testicles and FSH (follicle stimulating hormone) contributes to the formation of new sperm in the testicles.
Oxidative stress in obesity – and oxidative stress damages sperm
The body’s antioxidant levels were originally lower in the high-fat eating group than in the normal-eating subjects, which did not surprise the researchers, as the body’s antioxidant capacity is generally lower in overweight than in normal-weight people – possibly also because a high-fat diet could lead to more oxidative stress, which then naturally also consumes the available antioxidants more. Oxidative stress can also damage sperm, which in turn could explain their low numbers and poor motility in some overweight people.
Being overweight reduces testosterone levels – oestrogen increases
According to the researchers, testosterone levels tend to be low in overweight people because diets high in cholesterol have a harmful effect on the testosterone-producing cells in the testicles. A high-fat diet also increases the conversion of androgens (male sex hormones) into the female sex hormone estradiol (one of the oestrogens). The estradiol level rises, which causes LH and FSH levels to fall and, as a result, testicular functions to decline. High estradiol levels also have a specific toxic effect on spermatogenesis. Some human studies show parallels to the present study, so that the results of the study can certainly be transferred to humans to a large extent. A study (also from 2017) showed that taking a probiotic (L. paracasei) together with two prebiotics (approx. 2 g) and L-glutamine (500 mg per day) can increase the LH, FSH and testosterone levels in men – regardless of the respective diet.
How probiotics improve sperm quality and male fertility
Probiotics appear to improve male fertility and sperm quality via the following mechanisms of action:
- Probiotics increase testosterone levels,
- reduce the level of oxidative stress,
- improve metabolic health (the healthier the metabolism, the better the sperm function),
- lower cholesterol levels (the more balanced the cholesterol level, the better the sperm motility) and
- contribute to weight loss (which also leads to a decrease in scrotal fat (fat in the scrotum), which in turn improves testicular function).
Probiotics containing L. rhamnosus and/or L. paracasei, among others, can therefore most likely serve as a helpful dietary supplement to regulate body weight and blood fat levels. They also appear to be able to restore hormonal balance and improve sperm production and quality.