Why South Asian genes remember famine

Our genes are often thought of as a fixed blueprint, but what if our environment could change how they work? This is the intriguing idea behind epigenetics—a field that shows how our environment, combined with the body’s adaptive responses for survival, can influence gene expression without altering our DNA. In South Asia, famines such as the infamous Bengal Famine of 1943 caused immense suffering, and these hardships may have triggered genetic changes that continue to affect generations. Today, South Asians face an increased risk of developing Type 2 diabetes by age 25, whereas White Europeans generally encounter this risk around age 40. What is driving this difference in risk? This article will explore the science behind these epigenetic changes, their impact on the descendants of famine survivors and how these insights can shape public health, policy, and research.

The legacy of historical famines

In 1943, the Bengal Famine claimed around three million lives. Nobel laureate Amartya Sen argues that the severity of the famine was not merely a result of prior natural disasters and disease outbreaks in crops. Instead, it was primarily driven by wartime inflation, speculative buying, and panic hoarding, which disrupted food distribution across the Bengal region. Consequently, for the average Bengali citizen, death from starvation, disease, and malnutrition became widespread and inevitable.

The impact of the famine extended well beyond the immediate loss of life. Dr Mubin Syed, a radiologist specialising in vascular and obesity medicine, emphasises that these famines have left a lasting mark on the health of future generations. Dr Syed explains that South Asians, having endured numerous famines, have inherited "starvation-adapted" traits. These traits are characterised by increased fat storage. As a result, the risk of cardiovascular diseases, diabetes, and obesity is heightened in their descendants. This tendency towards fat storage is believed to be closely tied to epigenetic factors, which play a crucial role in how these traits are passed down through generations.

Epigenetic mechanisms and their impact

These inherited traits are shaped by complex epigenetic mechanisms, which regulate gene expression in response to environmental stressors like famines without altering the underlying DNA sequence. DNA methylation, a process involving the addition of small chemical groups to DNA, plays a crucial role in regulating gene expression. When a gene is 'on,' it is actively transcribed into messenger RNA (mRNA), resulting in the synthesis of proteins such as enzymes that regulate energy metabolism or hormones like insulin that manage blood sugar levels. Conversely, when a gene is 'off,' it is not transcribed, leading to a deficiency of these essential proteins. During periods of famine, increased DNA methylation can enhance the body's ability to conserve and store energy by altering the activity of metabolism-related genes.

Epigenetic inheritance, a phenomenon where some epigenetic tags escape the usual reprogramming process and persist across generations, plays a crucial role in how famine-induced traits are passed down. Typically, reproductive cells undergo a reprogramming phase where most epigenetic tags are erased to reset the genetic blueprint. However, certain DNA methylation patterns can evade this erasure and remain attached to specific genes in the germ cells, the cells that develop into sperm and egg cells. These persistent modifications can influence gene expression in the next generation, affecting metabolic traits and responses to environmental stressors. This means the metabolic adaptations seen in famine survivors, such as increased fat storage and altered hormone levels, can be transmitted to their descendants, predisposing them to similar health risks.

Research has highlighted how these inherited traits manifest in distinct hormone profiles across different ethnic groups. A study published in Diabetes Care found that South Asians had higher leptin levels (11.82 ng/mL) and lower adiponectin levels (9.35 µg/mL) compared to Europeans, whose leptin levels were 9.21 ng/mL and adiponectin levels were 12.96 µg/mL. Leptin, encoded by the LEP gene, is a hormone that reduces appetite and encourages fat storage. Adiponectin, encoded by the ADIPOQ gene, improves insulin sensitivity and supports fat metabolism.

Epigenetic changes, such as DNA methylation in the LEP and ADIPOQ genes, have led to these imbalances which were advantageous for South Asian populations during times of famine. Elevated leptin levels helped ensure the body could maintain energy reserves for survival, while lower adiponectin levels slowed fat breakdown, preserving stored fat for future use. This energy-conservation mechanism allowed individuals to endure long periods of food scarcity.

Remarkably, these epigenetic changes can be passed down to subsequent generations. As a result, descendants continue to exhibit these metabolic traits, even in the absence of famine conditions. This inherited imbalance—higher leptin levels and lower adiponectin—leads to a higher predisposition to metabolic disorders. Increased leptin levels can cause leptin resistance, where the body no longer responds properly to leptin’s signals, driving overeating and fat accumulation. Simultaneously, reduced adiponectin weakens the body’s ability to regulate insulin and break down fats efficiently, resulting in higher blood sugar levels and greater fat storage. These combined effects heighten the risk of obesity and Type 2 diabetes in South Asian populations today.

Integrating cultural awareness in health strategies

Understanding famine-induced epigenetic changes provides a compelling case for rethinking public health strategies in affected populations. While current medicine cannot reverse famine-induced epigenetic changes in South Asians, culturally tailored interventions and preventive measures are crucial to reducing metabolic risks. These should include personalised dietary plans, preventive screenings, and targeted healthcare programmes. For example, the Indian Diabetes Prevention Programme showed that lifestyle changes reduced diabetes risk by 28.5% among high-risk individuals.​

Equally, policymakers must consider the broader societal factors that contribute to these health risks, and qualitative studies highlight challenges in shifting cultural attitudes. Expectations that women prepare meals in line with traditional norms often limit healthier dietary options.Differing perceptions of physical activity can complicate efforts to promote healthier lifestyles. For example, a study in East London found that some communities consider prayer sufficient exercise, which adds complexity to changing attitudes.

Facing our past to secure a healthier future

As we uncover the long-term effects of environmental stressors like historical famines, it becomes clear that our past is not just a distant memory but an active force shaping our present and future health. Epigenetic changes inherited from South Asian ancestors who endured famine have heightened the risk of metabolic disorders in their descendants. For instance, UK South Asian men have been found to have nearly double the risk of coronary heart disease (CHD) compared to White Europeans. Consultant cardiologist Dr Sonya Babu-Narayan has stated, “Coronary heart disease is the world’s biggest killer and the most common cause of premature death in the UK.” With over 5 million South Asians in the UK alone, this stark reality requires immediate action. We must not only address the glaring gaps in scientific research but also develop targeted public health policies to tackle these inherited health risks. These traits are not relics of the past; they are living legacies that, without swift intervention, will continue to affect generations to come.

To truly address the inherited health risks South Asians face, we must go beyond surface-level awareness and commit to long-term, systemic change. Increasing funding for research that directly focuses on the unique health challenges within this population is non-negotiable. Equally crucial are culturally tailored public health initiatives that resonate with the affected communities, alongside comprehensive education programmes that empower individuals to take control of their health. These steps are not just about improving outcomes—they’re about breaking a cycle.

The question, therefore, is not simply whether we understand these epigenetic changes, but whether we have the resolve to confront their full implications. Can we muster the political will needed to confront these inherited risks? Can we unite our efforts to stop these risks from affecting the health of entire communities? The cost of inaction is not just measured in statistics—it will be felt in the lives lost and the potential unrealised. The time to act is now.

Written by Naziba Sheikh

Related articles: Epigenetics / Food deserts and malnutrition

REFERENCES

Safi, M. (2019). Churchill’s policies contributed to 1943 Bengal famine – study. [online] the Guardian. Available at: https://www.theguardian.com/world/2019/mar/29/winston-churchill-policies-contributed-to-1943-bengal-famine-study.

Bakar, F. (2022). How History Still Weighs Heavy on South Asian Bodies Today. [online] HuffPost UK. Available at: https://www.huffingtonpost.co.uk/entry/south-asian-health-colonial-history_uk_620e74fee4b055057aac0e9f.

Sayed, M., Deek, F. and Shaikh, A. (2022). The Susceptibility of South Asians to Cardiometabolic Disease as a Result of Starvation Adaptation Exacerbated During the Colonial Famines. [online] Research Gate. Available at: https://www.researchgate.net/publication/366596806_The_Susceptibility_of_South_Asians_to_Cardiometabolic_Disease_as_a_Result_of_Starvation_Adaptation_Exacerbated_During_the_Colonial_Famines#:~:text=This%20crisis%20could%20be%20the,adapted%20physiology%20can%20become%20harmful.

Utah.edu. (2009). Epigenetics & Inheritance. [online] Available at: https://learn.genetics.utah.edu/content/epigenetics/inheritance/.

Palaniappan, L., Garg, A., Enas, E., Lewis, H., Bari, S., Gulati, M., Flores, C., Mathur, A.,

Molina, C., Narula, J., Rahman, S., Leng, J. and Gany, F. (2018). South Asian Cardiovascular Disease & Cancer Risk: Genetics & Pathophysiology. Journal of Community Health, 43(6), pp.1100–1114. doi:https://doi.org/10.1007/s10900-018-0527-8.

Diabetes UK (2022). Risk of Type 2 Diabetes in the South Asian Community. [online] Diabetes UK. Available at: https://www.diabetes.org.uk/node/12895.

King, M. (2024). South Asian Heritage Month: A Journey Through History and Culture. [online] Wearehomesforstudents.com. Available at: https://wearehomesforstudents.com/blog/south-asian-heritage-month-a-journey-through-history-and-culture.