While couples often change their lifestyle in order to conceive faster, including crash diets, a new study in mice throws up the possibility that this kind of extreme dietary modification by the father might result in adverse effects on the child conceived in this manner.
A new study, published in the journal of The Physiological Society on October 15, 2019, suggests that a diet containing very low protein could harm the cardiovascular health of the offspring both in the newborn stage and in adult life.
Maternal health has long been known to affect the child’s health, but the new study specifically targeted the effect of protein deficiency in the father’s diet on the cardiovascular health of the offspring. This occurs because of the change produced in the sperms as well as in the seminal fluid, which surrounds the sperm.
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The study looked at male mice fed either on a poor diet, with inadequate protein content, or on a normal-protein diet, for 7 weeks or more. The researchers then produced mouse offspring using artificial insemination to get sperm from either the low-protein diet (LPD) group or the normal-protein diet (NPD) group. Two types of seminal fluid were also obtained by mating with mice that had been vasectomized – LPD and NPD seminal fluid.
The health of the offspring of these mice was thus studied in four ways: first, those conceived with sperm from LPD mice surrounded by seminal fluid from NPD mice; second, with seminal fluid from LPD mice surrounding sperm from NPD mice; third, when both sperm and seminal fluid were from LPD mice; and lastly, when both were from NPD mice.
The results showed that going on a severely restricted diet did not affect the father’s heart health, or the activity of the key renin-angiotensin system (RAS) that regulates blood pressure and fluid-electrolyte balance in the body.
However, the offspring suffered worse cardiovascular outcomes when either sperm or seminal fluid was from LPD mice, and the other component from NPD mice. Blood vessels in the adult offspring mice failed to respond properly to either vasoconstrictors or vasodilators. This was related to marked differences in the level of a key enzyme, the angiotensin-converting enzyme (ACE), within the lung and kidney as well as in the blood. ACE partly mediates the effects of the RAS. These changes were seen in offspring from 3 weeks of life onwards and persisted until they were adults. The same changes persisted in their offspring as well.
The kidneys of the adult offspring also showed changes in the expression of several molecules that modulate the RAS activity. Such a diet also changed the way certain proteins in the testes of the male offspring were expressed, leading to altered epigenetic modification of the DNA in these cells.
Older research has established a link between poor eating in the father and development in the embryo, fetal growth and metabolism, and cardiovascular illness. Overnutrition, obesity, excessive alcohol consumption and smoking have been shown to affect sperm quality and the health of the DNA. Sperm epigenetic changes are also observed in obesity and male infertility.
Seminal fluid also affects the early development of the offspring in many ways. It is necessary to help the uterus receive and establish the embryo at the beginning of pregnancy. When it is absent, fertility is impaired in male mice, along with poor development of the embryo following fertilization. The resulting offspring fail to show proper growth even in adult life; they also have metabolic and blood pressure abnormalities.
It would seem that metabolic disease in the offspring is programmed by protein malnutrition in the father during the period of conception, and this is linked to both sperm and seminal fluid abnormalities caused by protein deficiency.
This study builds on earlier knowledge by showing how sperm and seminal fluid from low-protein fed mice impacts the RAS, ACE activity and vascular health in the offspring, as well as affecting testicular epigenetic regulation. The researchers feel that a mismatch between the quality of the seminal fluid and the sperm might occur naturally in men on a crash diet, because seminal fluid shows rapid changes in quality with a poor diet, while the changes in sperm quality take a few months. Thus this discrepancy might persist for the first few months of a very restricted diet. If conception occurs during this period, the offspring might be affected the same way, with similar impact on their cardiovascular health.
Another possibly relevant area is in the use of in vitro fertilization (IVF) to help couples conceive, since typically only the sperms from the male partner are used, which might again cause a variation in the quality of the sperm and the seminal fluid.
Researcher Adam Watkins says, “It is important that we understand how and why paternal diet impacts on the offspring, so we can suggest preventative measures for couples who are trying to conceive, such as dietary recommendations.”
Morgan, H. L., Paganopoulou, P. , Akhtar, S. , Urquhart, N. , Philomin, R. , Dickinson, Y. and Watkins, A. J. (2019), Paternal diet impairs F1 and F2 offspring vascular function through sperm and seminal plasma specific mechanisms in mice. J Physiol. doi:10.1113/JP278270, https://physoc.onlinelibrary.wiley.com/doi/full/10.1113/JP278270