Friday, January 11, 2008

And Thus Said Barker

In the course of researching for a paper, I came across a very interesting concept. In the present day when a number of diseases ail us, it might be worth considering this theory. With the progress of biomedical sciences, we have been successfully able to combat a number of diseases to a great extent, if not totally. Not many people die of small pox, chicken pox, or cholera these days unless they live in extreme poverty and stressful situations. Yet a number of diseases that were not in extant even a 100 years back are now on the rise (diabetes, cardiovascular diseases, strokes). Most of them are directly related to our lifestyle, like a persistent period of improper diet, lack of exercise, stressful living, etc. So in theory, the prevalence of these diseases can be substantially lessened if we lead a healthy life.

So what new does the Barker Hypothesis say that we don’t already know? Eat well, sleep well, exercise daily, don’t stress out, and there you will stay healthy. But wait, the Barker Hypothesis throws a different light to the situation. Also called the Fetal Origin Hypothesis, this is what it says-

Apart from the lifestyle we lead, what we suffer from as adults could depend on what we were exposed to in-utero (in the womb). In other words when we were in the womb, if we got exposed to certain chemicals, drugs, metabolites, etc., we could be more prone to suffering from certain diseases in the later stages of life. We might not show any manifestations of it during our childhood or even in youth, but as we progress towards mid-life, we are prone to suffer from a number of diseases.

In other words, what we suffer from during old age depends a lot on what we were exposed to in our mother’s womb? That’s correct.

So what diseases are we talking about here?

Parkinson’s disease. Cardiovascular disease. Heart attacks. Male reproductive malfunction. You just name it.

Exposure to the pesticide DIELDRIN during pregnancy is predicted to cause serious health concerns to the fetus, increasing its risk of suffering from Parkinson’s disease. Though Parkinson’s disease is a disease of the brain and the neurons primarily concerning the elderly population, experimental and epidemiological finding suggests that the process of neurodegeneration begins much before. Thus developmental exposure to dieldrin causes persistent change in the dopaminergic system due to increased susceptibility to Parkinson’s disease. In other words, if your mom was exposed to pesticides when she conceived you, you in your old age will be prone to suffer from Parkinson’s disease.

Exposure to DIETHYLSTILBESTROL (DES) (a clinical agent) in pregnant women caused cervico-vaginal adenocarcinoma in their daughters. The carcinogen (DES) was taken by the mother, but the cancer appeared in the offspring and that too, only after the onset of puberty.

It is interesting to note further that women who were not themselves exposed to DES in-utero may have altered reproductive tract function if their mothers had been exposed in utero. This meant that maternal ingestion of DES during pregnancy could not only alter the reproductive capacity of the woman exposed directly with the fetus, but that the alteration may be passed on to another generation (the so-called DES granddaughter effect). So lets say your mom was exposed to pesticides and you were fine, but your daughter is at the risk of having reproductive anomalies just because your mother was exposed to pesticides and you were a silent carrier.

These effects are not just related to exposure to chemicals like DES and Dieldrin, but to biological factors (like undernourishment of the fetus leading to lower birth weight) as well. It goes like this. Fetal undernourishment in middle to late gestation leads to disproportionate fetal growth, and causes coronary heart disease later in life. This means that if your mom did not eat properly when she was pregnant with you, you are at a risk of developing coronary heart diseases when you are of middle age. Human studies have shown that men and women whose birth weights were at the lower end of the normal range, who were thin or short at birth, or who were small in relation to placental size have increased rates of coronary heart disease. Evidences and research findings show that coronary heart disease is associated with specific patterns of disproportionate fetal growth that result from fetal undernourishment in middle to late gestation. So undernourishment during pregnancy could make your child prone to having heart diseases and health related disorders later on in life.

Talking about low birth weight? Did you know that exposure to phthalates like DBP and DEHP could cause fetal low birth weight? And how might women be exposed to these compounds? Through the use of make up, nail polish, perfumes, creams, and body lotions. Although the cosmetics industry have come up with a lot of their own arguments, it still remains a fact that usage of perfumes and cosmetics with phthalates in them increases the chances of delivering low birth weight babies.

I will not go into the complicated mechanisms of how these happen, but would like to clarify certain things. All these findings include working with animal (mainly rodent) models as well as human models, and there is scope of a lot more research. Secondly, there is nothing concrete like a cause and effect relationship. Exposure to certain substances only make us more prone to suffer from certain diseases, doesn’t mean everyone in a population will start showing similar effects. We are all different, and in the complexity of this lie the beauty of biological sciences. But the take home message should be clear. We should definitely be more aware of the stuff we are exposed to, more so during our child-bearing years. For what we are exposed to could also affect the destiny of our future generations. I don’t mean be paranoid about the situation and take extreme steps to ensure you live in an axenic environment. That is not possible. But it doesn’t harm to be more conscious about our own bodies, health, and environment. No matter what, we will always be exposed to certain unwanted substances, and despite everything, our immune system will always devise new strategies to cope up. That is what evolution is all about.

For people who are interested in further readings, just google “Barker Hypothesis” and you’ll find the rest. Stay healthy, stay safe.


1 comment:

maxdavinci said...


I guess I was better of being ignorant!