Can eating carrots, lettuce, spinach, tomatoes improve sperm quality and chances of getting one’s spouse pregnant? CHUKWUMA MUANYA examines
Carrots-lettuceAre you firing blanks? Are you unable to get your spouse pregnant? Are you diagnosed of low sperm count, poor sperm motility and morphology? Do you want to boost sperm quality?
Recent study suggests that certain vegetables such as carrots, lettuce, spinach and tomatoes could help improve sperm quality; sperm motility – how quickly a sperm can swim towards an egg and sperm morphology – the size and shape of a sperm (for the best chance of successfully conceiving, a sperm should have an oval head and a long tail).
The study published in the peer-reviewed medical journal Fertility and Sterility noted that sperm quality could also be improved by quitting smoking if one smokes, trying to achieve or maintain a healthy weight, drinking sensibly and keeping the testicles cool.
The researchers from Harvard School of Public Health and Universities in Canada, Copenhagen, Murcia and New York, a study funded by a grant from the National Institutes of Health and the European Union looked at young men’s diets and analysed their sperm samples.
They found that men who ate a higher amount of three antioxidants found in fruit and vegetables had sperm with better motility and morphology.
The three antioxidants in question were: beta-carotene - found in carrots, lettuce and spinach; lutein - found in lettuce and spinach; lycopene - found in tomatoes.
According to the study, men who ate higher levels of beta-carotene and lutein had a 6.5 per cent increase in sperm motility, and those who consumed higher levels of lycopene had 1.7 per cent improved sperm morphology.
However, this study examined diet and sperm quality at the same time, so cannot prove cause and effect. Also, the study involved young healthy men so the results may not apply to different populations. “Still, increasing your intake of vegetables is unlikely to harm you or your sperm and has many other health benefits.”
In another study, researchers at the University of Western Australia have found that men who eat diet rich in antioxidants - vitamin E and beta-carotene - boost their chances of making a baby than those who do not. The study was published in the journal Ecology Letters.
In a study of crickets, the researchers found that a combination of these antioxidants provided to be the best weapon against sperm damage.
The study suggests that dietary intake of foods like cantaloupe, carrots, apricots, pumpkin and mangos - orange-coloured foods rich in beta-carotene - and almonds, soybean oil and broccoli, which are rich in vitamin E, could help maintain healthy sperm in men.
The Australian study follows on the heels of another review published in January in The Cochrane Library, which also found that men with low sperm counts or sperm mobility who took oral antioxidants like vitamin E, zinc and magnesium improved their chances of impregnating their partner.
Yet another study published in Yakhteh Medical Journal, demonstrated that the administration of carrot seed extract could overcome the reproductive toxicity of gentamicin.
The study by Iranian researchers at the Drug Applied Research Centre, Tabriz University of Medical Sciences, found that carrot seed extract was also able to induce spermatogenesis and cauda epididymal sperm reserves, probably mainly through the elevation of testosterone levels.
They wrote: “These results are very interesting if we bear in mind the suppressive effect of carrot seed extract on the female reproductive system reported by others. Therefore, it appears that this extract has opposite effects on male and female reproductive systems. As carrot is an easily accessible and popular vegetable, it is likely that its consumption would be an effective and safe way to reduce the toxic effects of chemicals on the reproductive system and infertility in males; a subject requiring further studies.”
Another study published in Fertility and Sterility found that intake of some foods boost semen quality.
The researchers from the Department of Reproductive Biology and Medicine, Instituto Bernabeu, Alicante, Spain, concluded: “Frequent intake of lipophilic foods like meat products or milk may negatively affect semen quality in humans, whereas some fruits or vegetables may maintain or improve semen quality.”
They compared dietary habits in normospermic and oligoasthenoteratospermic patients attending a reproductive assisted clinic.
The observational, analytical case-control study in private fertility clinics was on 30 men with poor semen quality (cases) and 31 normospermic control couples attending.
They wrote: “We recorded dietary habits and food consumption using a food frequency questionnaire adapted to meet specific study objectives. Analysis of semen parameters, hormone levels, Y microdeletions, and karyotypes were also carried out.
“Frequency of intake food items were registered in a scale with nine categories ranging from no consumption to repeated daily consumption.
“Controls had a higher intake of skimmed milk, shellfish, tomatoes, and lettuce, and cases consumed more yogurt, meat products, and potatoes. In the logistic regression model cases had lower intake of lettuce and tomatoes, fruits (apricots and peaches), and significantly higher intake of dairy and meat processed products.”
Botanically called Daucus carota, carrots belong to the family Apiaceae and is cultivated throughout the world as a useful vegetable. Apart from its wide usage as a vegetable, different parts of this plant have been used in folk medicine for the treatment of a broad spectrum of aliments including kidney dysfunction, asthma, worm infections, inflammation and leprosy.
According to some studies, carrot extract has also some protective effects on myocardial infarction (heart attack) and lindane-induced hepatotoxicity.
The plant has been extensively studied for its chemical composition and a large number of active ingredients such as volatile oils, steroids, tannins, flavonoids, and caroten have been isolated.
Recently, pharmacological studies have shown that Daucus carota seeds exhibit antifertility properties in females.
Majumder et al. have shown that the petroleum ether extract and fatty acids of carrot seeds are able to arrest the normal estrus cycle of the adult mouse and reduce the weight of ovaries significantly. They also found that treatment with carrot seed extract (CSE) can lead to a significant inhibition of delta 5,3-beta-hydroxy steroid dehy- drogenase and glucose-6-phosphate dehydrogenase, the two key enzymes involved in ovarian steroido- genesis, in mouse ovaries.
In another in vitro study carried out using an isolated rabbit ovarian perfusion system, it was found that progesterone and human chorionic gonadotropin-induced progesterone secretions are significantly diminished after the acute feeding of carrots.
The effects of carrot on human fertility have been also mentioned in Iranian traditional medicine. In the Zakhireh Kharazmshahi (Kharazmshahi’s Treasure), a book written by Seyyed-Esmail Jorjani born in the 11th Century, one chapter was allocated to the properties of carrots.
Interestingly, according to Jorjani, the effect of carrot on fertility is gender dependent. He claimed that carrot can increase the potency in men, while in women it stimulates menstruation, with its seeds being more effective than other parts of the plant. There is also a direct relation between potency in men and the levels of testosterone, which could be affected by gonadotrophins. It is also well-known that testosterone is able to increase spermatogenesis.
Meanwhile, the Harvard School of Public Health and Universities in Canada, Copenhagen, Murcia and New York, publication was a cross-sectional study looked for a potential association between a diet high in antioxidants and the quality of sperm.
According to the report, as this was a cross-sectional study it cannot prove causation. It cannot prove that the antioxidants caused better quality semen, as the relationship between the two is likely to be influenced by a variety of other confounding health and lifestyle factors.
Ideally, a randomised controlled trial would be carried out to prove cause and effect. However, such a trial randomising men to different diets and then following them up over months or years to examine their sperm quality may not be feasible or ethical.
The researchers recruited 389 young men from university and college campuses in Rochester, New York. A 131-item food frequency questionnaire at the start of the study was completed by only 194 of the men. Men were further excluded if they did not provide information on calorie intake, or if their calorie intake was less than 600 kcal or more than 15,000 kcal a day. The total sample size was 189 men with an average age of 19. Men were paid $75 to participate.
Each man provided a semen sample, which was analysed within half an hour for: semen volume; sperm count; sperm motility; and sperm morphology.
From the food and supplement frequency questionnaire, the researchers estimated the amount of the following micronutrients in their diet: vitamin A; vitamin C; vitamin E; and carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein and lycopene).
The researchers then performed statistical analyses to look for links between the amount of each micronutrient consumed and semen quality.
They took into account confounders such as age, body mass index (BMI), physical activity level, caffeine intake, alcohol intake and current smoking status. They also analysed the effect of how long the men had abstained from sexual activity (including masturbation) before the semen sample was provided.
The basic results showed increased carotenoid intake, especially beta-carotene and lutein, was associated with sperm that moved 6.5 per cent faster compared with those from men with the lowest carotenoid intake. This association was higher if the intake came from food rather than supplements.
Lycopene intake was associated with 1.7 per cent higher numbers of normally-shaped sperm compared with men with the lowest intake.
High intake of vitamin C (from food only) was associated with lower sperm count. The sperm concentrations were 22 per cent lower than in the men with the least intake of vitamin C.
However eating a bit more vitamin C produced the highest sperm concentration, count and motility. Vitamin C was not related to any change in sperm shape.
No associations were seen with intake of vitamin A or E, and none of the results were affected by BMI or smoking status.
Three foods (carrots, lettuce and spinach) accounted for 59 per cent of the beta-carotene intake and two foods (lettuce and spinach) accounted for 56 per cent of the lutein. The majority (98 per cent) of the lycopene was in five foods (tomato soup, tomato juice, salsa, ketchup and fresh tomatoes).
The researchers described a relationship between higher intakes of the carotenoids beta-carotene and lutein and greater sperm motility, and between higher intake of lycopene and increased number of normal-shaped sperm. They pointed out that this research does not prove that increased intake improves motility or shape of sperm and they do not know what effect, if any, increased consumption of these nutrients would have on men with fertility problems.
The researchers concluded: “This study shows an association between higher dietary consumption of food that contains more carotenoids and slightly better sperm motility and greater number of sperm with normal shape.
“However, these associations were small. For example, the World Health Organization defines sperm samples as adequate if the average number of sperm with a normal shape is four per cent or more. In this group of young men, the average was nine per cent (5 to 12 per cent), and was only 1.7 per cent higher in men eating more food containing lycopene.”
According to the study, there are other important limitations, including the following:
*As all assessments of dietary intake were self-reported, it is possible that estimations of carotenoid intake may have been inaccurate.
*The study has a cross-sectional design, which means it cannot prove cause and effect. As the researchers acknowledge, the observed relationship between sperm quality and dietary factors is likely to be influenced by confounding from other factors such as another substance in the food that is improving sperm quality, or other healthy lifestyle behaviours.
*The study was conducted in a sample of only 189 young men from one US region, who had an average age of 19 and none of whom had reported fertility problems. It is not known whether similar associations between carotenoid intake and sperm quality would be obtained from other samples of men, for example those of different ages, or those with fertility problems.
*In this sample of young men it is not known whether the observed differences in sperm quality would have led to any difference in the likelihood of successful pregnancy if they were trying to conceive with a partner.
The researchers wrote: “While the media has focused on the carrots, the study reports that 59 per cent of the dietary intake of beta-carotene came from carrots, lettuce and spinach. The lettuce and spinach were also the sources of 56 per cent of the lutein. While this study does not prove that any of these vegetables had a direct effect on sperm quality, increasing your intake of vegetables is unlikely to cause any harm.
“Analysis of the relationship between vitamin C and sperm quality gave a very wide range of results. Previous studies have shown that vitamin C can improve the motility and number of sperm of normal shape. Other studies have shown that it has no effect. Until results are more conclusive, it is best to eat the daily recommended amount of fruit and vegetables.
“The researchers conclude that a well-designed randomised controlled trial is required to determine whether eating more carotenoids improves sperm morphology and motility.
“However, eating a diet rich in fruit and vegetables is certainly not going to cause you any harm.”
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