The Epigenetics of Hunger

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PHNOM PEHN, Cambodia — From 1975 to 1979, the Khmer Rouge initiated the Cambodian Genocide that led to widespread famine, violence, repression and murder. It left two million individuals dead, many of whom died from malnutrition and hunger, and caused immense psychological damage to the survivors. Hundreds of thousands fled the country.

The Khmer Rouge left not only psychological and physical damage, but some believe that it also imprinted itself into the DNA of the Cambodians conceived and born during the genocide, leaving them at a higher risk of diabetes, obesity, heart disease and high blood pressure.

Lim Keuky, president of the Cambodian Diabetes Association, is witnessing an unbelievably high number of cases of diabetes in Cambodia. Instead of the standard patients with Type 2 diabetes who are older and overweight, these individuals being diagnosed with diabetes are in their 30s with average weights. They were also conceived and born during the Khmer Rouge.

Thirty years earlier in the Netherlands, from November 1944 to May 1945, 20,000 individuals died from hunger during the Dutch Hunger Winter because the Germans stopped all food from entering the country. In desperation, people resorted to eating grass and tulip bulbs. In the 1990s, scientists began studying the individuals who were conceived during the Dutch Hunger Winter to research the long-term effects of the famine.

The scientists found that these individuals had higher levels of blood glucose (a predecessor to diabetes), higher BMIs and were at a higher risk of developing coronary heart disease. These observations were not only seen in the individuals conceived during the Dutch Hunger Winter, but in their children as well. Somehow, these characteristics were passed on to the next generation.

Following the pattern of inherited diseases in the individuals born during the Dutch Hunger Winter, it is reasonable to hypothesize that the health conditions of the Cambodians born during the genocide could also be passed on to their children due to epigenetics.

Epigenetics are modifications to DNA that do not affect the sequence of the genetic code itself. These modifications are small chemical tags (methyl groups) to the DNA that can change the behaviors of the cells. Methylation of DNA makes the genetic code inaccessible to transcription factors, inhibiting the expression of that gene, which creates more genetic variation than just the DNA sequence. Epigenetics has already been associated with schizophrenia, rheumatoid arthritis, cancer and chronic pain.

The human body has the ability to adapt to starvation and malnutrition by epigenetically turning some genes off or on to maximize the efficiency of metabolism. If the modifications occur during a crucial phase of development, the altered function of the cells can be set for life, and may even be passed on to later generations. The children of the survivors of the Khmer Rouge and the Dutch Hunger Winter may have genes already programmed to survive in meager food circumstances.

Maternal nutrition is not the only factor that contributes to health conditions. There are a multitude of complex factors, including environmental factors and the child’s upbringing, that can lead to disease. Further research and screening of Cambodians is needed, and Keuky hopes to test 100,000 Cambodians by 2016 to see how they have or have not been affected by the starvation of their grandparents.

Epigenetics could change how citizens and policy makers understand poverty. The effects of poverty (famine, malnutrition, starvation) will not only affect one generation, but it could lead to a multigenerational effect. The events that one generation experiences could be passed down to their children and grandchildren through their DNA. This drastically expands the number of individuals who are suffering, or who will suffer, from the effects of poverty. By not aiding those in the present who are living in poverty, are we condemning the unborn to the same experience?

Sources: National History Magazine, Popsci, The Daily Beast
Photo: PRI

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