An unhealthy diet, lack of exercise, and smoking – considered to be a relatively recent societal curse – are all risk factors to heart disease. But if that is the case, did heart disease exist thousands of years ago? Renowned UTHealth Houston cardiologist Jagat Narula, MD, PhD, discussed what examining 4,000-year-old mummies and living hunter-gatherer tribes suggests about the basis of heart disease and whether we could eliminate it in our lifetime.
According to the World Heart Federation, cardiovascular disease continues to be the leading cause of death both in women and men, across the developed and developing world and all racial and ethnic groups. Unhealthy eating habits and lifestyle patterns lead to the development of risk factors that promote atherosclerosis or deposits of fat in the coronary arteries, which supply blood to the heart. The risk factors associated with heart attacks include high blood pressure, elevated blood cholesterol levels, high blood sugar, and smoking.
“Around 3,000 to 4,000 years ago, we did not have processed food, smoking or pollution, nor did we live a sedentary life. We must have eaten better, we must have exercised better in absence of other modes of transport. It was logical to presume that we must not have suffered from heart disease at that point in time,” said Narula, president of the World Heart Federation and executive vice president and chief academic officer at UTHealth Houston.
A team of rather unorthodox investigators, called the HORUS Group, which includes Narula, has now studied cardiovascular disease in nearly 300 mummies or human remains from Egypt, Peru, Bolivia, the Aleutian Islands, Southwest United States, and Greenland to examine their lifestyles and cultures, and determine if a simple lifestyle, without all the risk factors we have today, could eliminate the risk of cardiovascular disease. The multidisciplinary research group included cardiologists, radiologists, pathologists, geneticists, basic scientists, anthropologists, and archaeologists. They followed their intriguing studies by exploring the heart health of about 750 living hunter gatherers from Bolivia who have long lives with no heart disease.
The researchers used modern technology like CT scans to identify any calcification of the arteries. Narula reminded us that calcium deposits occur in atherosclerotic lesions, and a CT scan is commonly used to screen for the presence of heart disease. HORUS investigators believed that they would not find any calcium in mummies. Intriguingly, more than one-third of the initial group of Egyptian mummies showed evidence of coronary atherosclerosis as identified through calcium deposits. The team was bewildered to discover heart disease in people living up to 3,500 years ago, but quickly realized the reason for those results might lie in their societal characteristics.
“They were all nobility and elites; they had evolved from hunter gatherers to a civilized society,” said Narula, professor and K. Lance Gould Distinguished University Chair in Coronary Pathophysiology at McGovern Medical School at UTHealth Houston. “They were carried in palanquins. They started cultivation and animal husbandry and had access to abundant food and meat. They consumed multiple meals every day; they essentially lived in modern society.”
The team subsequently traveled to the Andes mountains in Peru, studying naturally mummified remains of farmers and manual laborers. Half of them lived a vegetarian lifestyle, while the other half consumed lean meat such as alpaca. The team assumed that this population should have evaded cardiovascular disease, but they found evidence of calcification in one-fourth of the Peruvian mummies as well. Some autopsy reports from those with cardiovascular disease suggested simultaneous presence of black lungs. Similar calcium scan patterns were seen in the Aleutian Islands, Greenland, and Southwest U.S. These societies lived in low-ceiling houses, subterranean houses, igloos, or pit holes. They cooked indoors and lit fires inside for warmth.
“They were exposed to smoke-filled indoor environs,” Narula said. “In developing countries, women and children are similarly exposed to indoor pollution. Since all cultures that we studied revealed the presence of disease, it became clear that (unlike other animals) we carry a genetic background that allows for development of heart disease. Yet all were exposed to disease-inducing behavior.”
The HORUS group then collaborated closely with investigators of the Tsimane Lifestyle Project in Bolivian jungles, studying hunter gatherers who live into their 80s, 90s, and beyond. Members of the Tsimane walk up to 20,000 steps every day in search of food that includes monkeys, jaguars, pigs, and piranha, and they have access to some wild fruit like papaya and plantains. They just eat one meal a day in the evening. They live in open huts and do not smoke. Their blood cholesterol does not exceed 70, their systolic blood pressure is around 115, their blood sugar levels remain under 80, and their BMI is at 24. Heart calcium scans performed in more than 700 Tsimane, including octogenarians and nonagenarians, revealed that they have the healthiest hearts described from anywhere on the planet. Narula asks: If the Tsimane can avoid having heart disease, why can’t we?
Narula, as the new president of the World Heart Federation, is leading their massive effort- CARDIO4Cities program in collaboration with Novartis Foundation and have recently submitted a large grant from UTHealth Houston, to reach 150 million people in 40 metropolises across the world. The Novartis Foundation leader, Ann Aerts, MD, said the effort is a multisector, data-driven approach to reduce risk factors in large urban populations.
Narula added, “There is no one-size-fits-all approach to improving heart health. Every population is susceptible to different risk enhancers based on where they live and their lifestyles, whether that’s having higher tobacco use or sodium intake, exposure to severe air pollution, or to war and conflict. The stakeholders must look at the risk factor prevalence in their regions to develop strategy in the right direction.”
Narula is also leading the World Heart Federation effort, in collaboration with Economist Impact and Novartis, to rate major world cities by status of their heart health, called City Heartbeat Index. The goal is to raise awareness about the factors that contribute to cardiovascular disease and foster collaboration among diverse stakeholders to develop and implement evidence-based and scalable interventions, encourage improved public health infrastructure, and promote equity in access to health care services and prevention programs. The first list of 50 major cities was released on Aug. 31, 2024.
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