You may have seen this recent study reported in the newspapers making the argument that a high fat diet can lead to poorer sperm quality. In particular, saturated fats have taken a bashing. Let’s examine this study more closely.
Objective: To assess the relationship between dietary fat intake and sperm quality.
Methods: The researchers took data from 99 subjects who provided comprehensive dietary data and whose semen quality was analysed. Fatty acid levels in sperm and seminal plasma were measured. The men were primarily Caucasian (89%) and had a mean age of 36 years with an incidence of overweight or obesity of 71%.
Results: Higher fat intake was correlated to lower sperm count and concentration. The third consuming the most fats had 43% lower total sperm count and 38% lower sperm concentration than men in the lowest third. Levels of saturated fats in sperm show a negative correlation to sperm concentration but saturated fat was unrelated to sperm levels. Those consuming the highest proportion of omega-3 fatty acids had the best results showing a 1.9% higher sperm morphology than men in the lowest third who consumed the least fats in their diet.
Conclusion: The researchers conclude that high intake of saturated fats was negatively correlated to sperm intake while higher intake of omega-3 fatty acids was positively related to sperm morphology.
This study has been reported across numerous daily newspapers which all report that fats, and saturated fats in particular are detrimental to sperm quality and health. However, it requires some important qualifications before we start ditching fats from our diet.
1. Low sample size – A sample size of 99 men is not very large at all and something the authors themselves agree requires a large pool of men to be studied before making firm conclusions.
2. Correlation is not causation – Much like the study on red meat we discussed yesterday, all this study shows is a correlation between high fat intakes and poorer sperm quality. It does not mean that the former caused the latter.
3. Poor dietary control – Much like the red meat study, this one relied on participants fulfilling food questionnaires which make the dietary control very poor. Without someone actually monitoring every item ingested there is a very high likelihood that subjects’ memories of what they eat is inaccurate.
4. Sperm quality still normal – Despite the association between fat intakes and sperm count and concentration, none of the men had a sperm count or quality outside the normal range. This means that their fertility would be unaffected as they were all within the normal range.
5. Overweight subjects – The fact that 71% of the men were classed as overweight or obese makes it hard to draw inferences for those men who maintain a healthy weight. Much like the red meat study, this one claimed to have stripped out the effects of overweight and managed to analyse the impact of fat consumption in isolation but, as we saw in the red meat analysis, this can produce questionable results which do not correlate to the actual raw data. For all we know, being overweight could be the major factor behind poor sperm counts with those consuming the most fats likely to be the most overweight.
6. Low Carbohydrate Diets – Following on from the point above, it is likely that these men would be following the typical American diet which is high in carbohydrates and fats. Such a diet will lead to an increased likelihood of gaining body fat as well as incurring diseases related to insulin resistance such as diabetes. Both the gaining of weight and insulin resistance is linked to declines in fertility and negative effects on testosterone levels in men. By contrast, those who follow a low carbohydrate, high protein, moderate to high fat diet as exemplified by those following a Palaeolithic or ketogenic diets, will be much better able to oxidise saturated fats for energy and should therefore not suffer from the health consequences of a given level of fat consumption to the same extent. In particular, if subjects are consuming a higher fat diet and burning them off rather than storing as fat, it is unlikely they would suffer the negative effects on sperm quality seen in this study.
Given the fact that both low fat (2) and low carb diets (3) have previously been associated with poorer testosterone levels, it is hard to draw any firm conclusions from this study at all. Given the preponderance of evidence which shows that being overweight is linked conclusively to lower levels of testosterone and sperm quality, the take home message from this study is to ensure you keep in good physical condition and not worry unduly about fat intake. Fish oil consumption is something we have spoken about previously in our essential fats article and their usage is highly recommended along with other supplements shown to enhance testosterone naturally. Apart from that, avoiding a typical high fat, high carb, junk food diet as seen by the men in this study is quite an obvious thing to avoid we would hope.
Author: Reggie Johal
1. Jill Attaman et.al (2012): Dietary fat and semen quality among men attending a fertility clinic.
2. Dorgan JJF, Judd JJT, Longcope CC, Brown CC, Schatzkin AA, Clevidence BBA, Campbell WWS, Nair PPP, Franz CC, Kahle LL, Taylor PPR. Effects of dietary fat and fiber on plasma and urine androgens and estrogens in men: a controlled feeding study. The American journal of clinical nutrition
3. Lane AR et.al (2010): Influence of dietary carbohydrate intake on the free testosterone: cortisol ratio responses to short-term intensive exercise training.”
© 2012, Reggie Johal. All rights reserved.