Why Do Women Live Longer Than Males?

On average women live 4.2 years longer than men, and the difference in age is predicted to increase to 4.8 years by 2050.  Most people equate the difference in life span between the two genders to males making more unhealthy choices.  However, recent research has shown that the difference in age longevity could be biological.

Figure 1. Life expectancy of females is higher than females and it is projected that i will continue to be higher.

There is well-documented evidence that show that excess mortality rate in men is in part due to cardiovascular diseases.  Males are much more prone to cardiovascular risks than women. The occurrence of coronary heart disease is three times more frequent in men than females.  Moreover, mortality rates due to CHD are five times more in men than women. However, as men and women continue to age, the gender gap in cardiovascular risk goes down due to menopause in women
Estradiol plays an integral part in reducing cardiovascular diseases in women.  Estradiol is a sex hormone that is present in females; nevertheless, there is very small amount of estradiol in men as well.   Estradiol significantly affects the endothelial lining of blood vessels.  Endothelial lining of blood vessels are important when looking at occurrences of heart disease.   This is because of endothelial lining controls blood vessel constriction and dilatation, which in turn affects how the heart functions.   Estradiol interacts with nictric oxide enhancing the vasodilatation in females; as result, the blood vessels are not easily clogged, which reduces the risk of heart injury.

Structure of Estradiol

Another reason for longevity of females is that they are not prone to as much oxidative stress than males.  This oxidative stress arises from free radicals.  Free radicals are reactive oxygen species that are produced in the mitochondria and result in damage of parts of the cell, which is the main reason for aging.   Naturally, the defense system counteracts the free radicals by producing anti-oxidants.  The balance between the free radicals and antioxidants determine amount of damage and aging during the lifetime.   Mitochondria from females produce less amount of hydrogen peroxide, which causes oxidative stress.  Moreover, females produce more antioxidants than males.  As a result, oxidative damage is higher than females.  For instance, the oxidative stress causes four-fold times higher in males’ mitochondrial DNA than females’.   Estrogen levels contribute partly to the reduction of oxidative stress in females.  Estrogen enhances the production of antioxidants, which reduce the production of free radicals in the mitochondria.  This could explain why females have longer life span than males.
Another reason for female age longevity is that females have longer telomeres.  Telomeres are non-coding DNA repeating sequences found at the ends of all chromosomes.  The telomeres are responsible for protecting the ends of chromosomes from end to end fusion, recombination and degradation.  During replications up to hundred base pairs from the

Telomerase elongating telomeres

telomere repeats are lost.  Therefore, after several replications the chromosomes are longer protected due to the shortening of the telomere.   Since the chromosomes are longer protected by telomeres, the cells are longer able to go through cell division, and they eventually become apoptotic (die).   Therefore, telomere shortening weakens organ regeneration.  This because the cells in the organs go through apoptosis due to telomere shortening, and after a period of time, the number of dead cells increase impeding the regeneration of the organs.   Since telomeres are longer in females, cells in males have shorter lifetime and their organs are impaired at younger age than in females.  In addition, estrogen enhances the production of telomerase.  Telomerase is responsible for inhibiting the degradation of telomeres during replication.   Therefore, female telomeres shorten at much lesser rate than in males.  As a result, females are able to live longer than males.

In conclusion, recent studies have revealed more biological evidence that accounts for higher life expectancy in females than males.  Males are more prone to coronary heart disease, less organ regeneration, more oxidative stress.  This is because of the lack of estrogen production in males.  On the other hand, females produce high levels of estrogen before menopause, which accounts for their age longevity.  High estrogen levels are responsible for blood vessel vasodilatation, which prevents blood vessel clogging and reduce coronary heart diseases.  Moreover, estrogen is also responsible for reducing oxidative stress by producing antioxidants.  This results in slower aging process in females.  Additionally, estrogen enhances the production telomerase that inhibits telomere shortening.  Consequently, lifetime of individual cells and organs in females is higher.  There are other factors that could also increase the life expectancy of females that are not discussed here.   These evidences suggest that males could be biologically prone to higher mortality rates at younger ages than females.

REFERENCES

http://en.wikipedia.org/wiki/Estradiol

Tom Eskes,  Clemens Haanen. “Why do Women Live Longer than Men”European Journal of Obstetrics & Gynecology and Reproductive Biology. Volume 133, Issue 2, August 2007, Pages 126-133

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~ by chuchu09 on December 9, 2009.

15 Responses to “Why Do Women Live Longer Than Males?”

  1. The role of free radicals is an extremely hot topic right now. They are thought to cause the effects of aging and perhaps promote the growth of cancerous tumors. I think every other all natural, organic, good-for-you food and juice says that it neutralizes free-radicals. It’s if societal dietary trends would affect thi trend. But that also brings to the forefront the question: doe women eat/live healthier than men?

  2. I just looked into this and found a paper that also questions the attribution of the gender gap in life span to unhealthy choices, since currently, more and more women are making the same unhealthy choices that men do. However, the paper I found attributes the gap, not to hormonal differences (i.e. estrogen, testosterone), but to the larger body size of males. In some ways, this makes sense, because a larger body size requires more cell divisions, which also shorten the telomers.
    http://www.stindl.info/pdfs/Stindl2004.pdf

    However, I don’t think the larger body size tells the whole story, because if that were true, then I would think that smaller creatures, such as mice and insects, would live longer than larger animals, and that is definately NOT true. Rather, life span may be determined by some sort of interplay between body size, genetics, and hormone activity.

  3. In my biology senior seminar, we talked about a similar topic – estrogen and its role as a cardioprotective agent. At the time I researched a similar paper that looked at the effects of dietary isoflavones on rat heart tissue. Isoflavones often act as phytoestrogens in mammals and in layman’s terms are known as antioxidants. What this study found was really interesting. Basically, the rats were either fed on a high-soy diet (full of phytoestrogens) or a phytoestrogen-free diet. After a specific amount of time, the rats were sacrificed and saggital sections of their hearts were examined for tissue remodeling. A normal heart contains cardiomyocytes (heart muscle cells) that are of a certain length and width on average. These cells provide optimal contraction of the heart. If the cardiomyocytes become elongated though, heart contractile function suffers. We see this specifically in conditions like congestive heart failure where the heart can no longer effectively pump blood because of stretched out heart muscle.

    The researchers found that rats fed on phytoestrogen-rich diets had much healthier hearts. (They specifically looked at the left ventricle.) Rats on a phytoestrogen-free diet experienced heart remodeling and had significantly larger left ventricles than those with fed on phytoestrogens. So, this suggests that dietary antioxidants are a good idea for heart health!

    The article is way cool, so if you’re interested in this, please check it out here. Even if you don’t read the whole article, take a look at the pictures of the heart sections about 3 pages down and you’ll see what I’m talking about with heart remodeling.

  4. I’ve always been quite interested in the contrasting life spans between males and females, particularly since my father nearly died of a heart attack. Although this article helps explains a lot of the “how” involved with women potentially living longer than men, a lot of what I am still concerned with is the ‘why?’. I could understand how this could in some way be derived from some type of adaptive evolutionary advantage. Since one male can obviously impregnate several females, it seems as though it would make sense that the females of a species have a longer life span than the males (in terms of the preservation and proliferation of the species). Although I’m sure this concept potentially disgusts several people since we like think of humans as living a monogamous lifestyle, one must admit that although monogamy in and of itself may also be a trait to improve the success of a species (the two same people always being responsible for raising their offspring), it does not seem absurd to think that some residual genetic traits still reside in us that were designed for a non-monogamous lifestyle. It seems that quite often many people tend to elevate the human species above others, even though there are innumerable ways in which we behave in the exact same ways as the more ‘primitive’ species.

  5. First, I really enjoyed this article. It was very thought provoking. Plus, I am always amazed at the things that scientists research, how they come up with their ideas just amazes me. Secondly, to address Amanda’s comment, I agree with you that there seems some sort of interplay between body size, genetics, and hormone activity. However, I do think body size does have a lot to do with longevity. I found this article that compares life spans and heights as well as various lifestyles (eating choices and activity level) that I thought supported your article. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1071721/

    So I guess, I would be really interested in seeing if there were a correlation between the two articles. Do taller people have shorter telomeres then shorter people? I would ask the same question for oxidative stress the other things mentioned in the article. Is there a correlation between body size and these traits in people?

  6. To take this post in a fairly different direction, the estrogen question is very compelling to me since I did a research project involving the hormone last summer. I looked at medulloblastoma and how estrogen affects the brain tumor. In this post, it is explained that estrogen may lead to lower CHD levels in women, since they express higher levels of estrogen. However, during fetal development and the early stages of life, boys have higher estrogen levels. This hormone is partially what differentiates the male from the female brain during development. Due to the higher estrogen levels in the brains of boys, they show about 75% (I think) of the cases for medulloblastoma. For my research, I was looking at Faslodex (an estrogen receptor antagonist drug currently used for breast cancer treatments). We found that tumors treated with this drug had an arrest in tumor growth. I looked at vascularization in the tumors, which deals with endothelial cells and blood vessels. However, there were the same levels in both tumor groups. I then looked at cell division and found that the estrogen receptor antagonist actually led to lower levels of cells undergoing mitosis. This post reminded me of the specifics of my research, especially the role of estrogen in the separate genders.

  7. Obviously the statistics here show that women tend to live longer than men given all of the underlying variables. However, I would like to see how this blog post might overlap with a previous blog post about drinking wine reduces the risk of various cardiac ailments. This blog post specifically cites resveratrol and HDL-Cholesterol as the main beneficial chemicals in red wine.

    I know that this blog post really steered clear of lifestyle-related variables, but frankly, I’d like to know: as a male, how can I offset these biological flaws and extend my life?

  8. One thing skipped in both the article and the comments left is the evolutionary significance of these biological differences, that begs the question (like so much of evolution does): why? Now, this is not to say I feel cheated; quite the opposite, I’m looking forward to a full and happy life. But the hormone levels, the capacity to fight CHD, the increase resistance to oxidative stress, and all the other biological factors develop in humans independently of environmental factors. So, have women evolved to be biologically superior to men? I think these findings pose interesting questions not just for environmental factors, but evolutionary as well.

  9. You mentioned that Estradiol is a sex hormone that is present in females and mentioned it’s role in reducing the risk of heart disease. I was wondering what it’s function as a sex hormone is?

  10. You mentioned that Estradiol is a sex hormone that is present in females that reduces the risk of heart disease. I was wondering what its role as a sex hormone is in the female biological make-up?

  11. While there is a significant difference between the two sexes in life expectancy, I actually had a psychology book that performed an interesting statistical analysis (called a multivariate analysis) that showed that if you take into account the death rate of males from accidents, injury, and war deaths, the difference (while there is still a small one) is no longer significant. While this book is a little old (I took the class my sophomore year and had an older copy of the book), it still suggests an interesting behavioral factor that I don’t see addressed in these biological studies.

    Another suggested is that women have much lower iron levels than men, and iron plays a role in creating those free radicals you were talking about. The “deficiency” in iron experienced by women during menstruation may actually be helpful for reducing oxidative stress.

  12. It seems interesting that Estradiol helps to prevent cardiovascular disease. Although I think it would be unwise to increase the amount of Estradiol in males to try to counteract any genetic proclivity to cardiovascular disease, has there been any research in generating organic compounds similar to Estradiol that may react similarly to Estradiol to help prevent cardiovascular disease? It would be interesting to try to get rid of the sex hormone part of the organic compound and keep the vasodilator aspect to prevent cardiovascular disease. I wonder also if the Estradiol works in other ways (similar to antioxidants) to help prevent cardiovascular disease as well.

  13. It is interesting how my topic and is somehow connected to yours. The connection of Estradiol with the longer life has interested many pharmaceutical companies. Resveratrol also have the safe effect in a way that it imitates Estradiol. RSV binds to the estrogen receptors and initiates many cascades. The interesting and most tiresome part of Estradiol, we see that the Estradiol binds with many cascades that some drugs might work as Estradiol-agonist while when they go to different part of the bodies in Estradiol-antagonist. This makes drug makers to hard to understand and synthesize Estradiol looking molecules.

  14. In reference to Abel’s comments about estradiol attracting the interest of pharmaceutical companies: would the administration of estradiol in men have any averse effects on the body’s natural production of sex hormones (viz., testosterone) in males?

  15. Women and cardiovascular diseases:
    Cardiovascular diseases ranks first among all disease categories in hospital discharges for women. It includes coronary heart disease(CHD), stroke, and other cardiovascular diseases. The good news is that you can reduce many of your risk factors for heart disease and stroke with a few lifestyle changes. Researchers have found certain factors that play an important role in a person’s chance of developing heart disease. These are called risk factors. Some risk factors can be changed, treated, or modified and some cannot. But by controlling as many risk factors as possible, through lifestyle changes and/or medicine you can reduce the risk of heart attack and stroke.

    http://www.heart-consult.com/articles/192/does-gender-matter-females-and-cardiovascular-diseases

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