The Tsimane – A Window into the Paleolithic World
The Tsimane (pronounced ‘chee-mah-nay’) are a traditional hunter-gatherer society who live in the rainforests of the Amazon region of Bolivia. There are only about 16,000 of them alive today with most living along a tributary of the Amazon River called the Maniqui River. They enjoy a very active pre-industrial way of life, spending their time gathering wild plants, hunting, fishing and farming. The Tsimane are in essence living a lifestyle similar to that of people in Paleolithic times.
Recently the results of a study on the Tsimane were published. The participants were Tsimane people forty years of age and older. They were assessed for plaque build-up in the walls of their coronary arteries (the arteries that supply blood to the heart) using CT scans of the heart. CT (computerized tomography) scans reveal calcium build-up in coronary artery walls and are considered the best screening test for discovering clogged arteries (atherosclerosis) and increased risk of heart disease. The results are reported as CAC (coronary artery calcium) scores. A score of zero indicates no calcium build-up and no to extremely low risk of heart disease. CAC scores from 1 to 100 indicate low risk; scores of 101 to 400 indicate intermediate risk; scores over 400 show high risk (1).
The study showed that an astonishingly high number of Tsimane people have no risks for heart disease. Results revealed that 85% of the total Tsimane population had CAC scores of zero, 13% had CAC scores between 1 and 100 and only 3% had CAC scores higher than 100. Elderly Tsimane people were also benefiting from low CAC with 65% of those over 75 years of age showing a CAC of zero and only 8% having CAC scores of 100 or more. (2). Alarmingly, the average CAC scores of people living in the modern industrialized world are five times greater than those seen in the Tsimane population. Similar recent scans of 6,814 North Americans showed that only 14 % have CAC scores of zero while 36% have scores between 1 and 100 and 50% have scores over 100. (3,4)
Other study findings in Tsimane people included average LDL-cholesterol levels of 2.35 mmol/L, an optimal level for health. Average blood pressures were 116/73 and these excellent pressures remain the norm even in Tsimane people over the age of 75. Obesity, regular cigarette smoking, high heart rate, high blood sugar, insulin resistance and diabetes were rare. Average HDL-cholesterol levels were 1 mmol/L, a low level for this “good” type of cholesterol. However, growing evidence is pointing out that the quantity of HDL is not as important as the way it functions. A high saturated fat diet is one factor that leads to poor performance of HDL. The Tsimane eat a diet low in saturated fat. (2)
Similar to many other societies living a traditional subsistence lifestyle, inflammation levels are high in the Tsimane people. Their blood levels of high-sensitivity C-reactive protein (hs-CRP – a measurement of inflammation) were found to be high, being above 3 mg/dL in 51% of the subjects. (A normal hs-CRP measurement is less than 1 mg/dL (5).) High biomarkers of inflammation often indicate a higher risk of unhealthy arteries. However, in the case of the Tsimane, who exhibit overwhelmingly healthy arteries, it is likely that their high rates of infectious diseases and parasites are causing the inflammation. (2)
Conclusions of this study state that a lifetime of very low LDL, low blood pressure, low glucose, normal body-mass-index, no smoking and lots of physical activity result in avoidance of coronary atherosclerosis despite a high infectious inflammatory burden. Lead scientist of the study, Professor Hillard Kaplan, University of New Mexico, stated, “Our study shows that the Tsimane indigenous South Americans have the lowest prevalence of coronary atherosclerosis (hardening and narrowing of the arteries) of any population yet studied.” (2)
How can these simple people who spend most of their time gathering enough food to feed their families be blessed with freedom from heart disease? An examination of the details of their lives might give us some clues.
LESSONS TO BE LEARNED FROM THE TSIMANE
The Tsimane are extremely physically active. Men spend an average of six to seven hours a day in physical activity as they hunt, fish, gather foods and look after their small farms. Women are active four to six hours daily, helping in food gathering as well as preparing meals and looking after children. It is estimated that Tsimane people are inactive for only about 10% of their waking hours (6). Compare this to the norm in industrialized societies where inactivity takes up closer to 55% of the day (6,7).
The Tsimane eat a carbohydrate-rich diet of whole complex carbohydrates that are non-processed and rich in fiber. Two-thirds of their diet consists of the starchy carbohydrates that they grow – rice, plantains, manioc root and corn. The other third of the diet is foods that they hunt and gather – carbohydrates such as fruit and nuts, freshwater fish and wild animals such as wild pigs, tapir or capybara (a South American rodent that can grow to a size of 66 kilograms). Carbohydrates provide 72% of Tsimane calories, most of which are derived from healthy whole foods (2). Compare this to the 50% carbohydrate diet of the modern world of which a large proportion are highly processed.
The Tsimane eat only wild meat and their diet is low in fat. About 14% of Tsimane calories come from a mixture of plant and animal protein. Carbohydrates provide 72% of calories and the balance, about 14% of calories, come from fat. Tsimane people do not eat dairy and they eat very few eggs, an amount that contributes only about one-half of 1% of their daily calories. The average amount of fat eaten daily is 38 gm of which 11 grams is saturated fat (8). Tsimane meats are derived from wild animals that are naturally low in fat and especially in saturated fat, with about 6 to 16% of the calories they provide coming from fat. This is a far cry from meat sourced from the domestic animals of today which offer 40 to 60% of their total calories from fat (9). The average modern day eater derives 34% of his daily calories from fat which includes about 26 grams of saturated fat. Tsimane people eat no trans-fats and very few simple sugars. In contrast, people of the modern industrialized world still eat trans-fats, in spite of their known harms, and an average of 22 teaspoonsful of sugar a day.
The Tsimane are not overweight.
The Tsimane rarely smoke.
Though the Tsimane have high levels of inflammation, they have extremely low risk for cardiovascular disease. This fact is helping to shed light on the actual cause of atherosclerosis. It has been known for more than a century that the arteries of mummies from ancient cultures such as Peru, Egypt, the Aleutian Islands and even those of Native Americans display well-developed atherosclerosis. Back in 2014 there was a new flurry of scientific exploration of mummified remains as scientists searched for reasons why atherosclerosis, assumed to be a disease of modern life, was present in these historic cultures. What they found in these archaic bodies were signs of parasite infestations. And so they theorized that chronic inflammation brought on by aging might be the trigger for the development of atherosclerosis, and not other possible factors such as high blood pressure or high LDL levels (10). The recent studies of the Tsimane refute that theory. These people endure high levels of inflammation stemming from their high rate of infections and parasites, yet their arteries are the healthiest of any population in the world.
Following in the footsteps of the heart-healthy Tsimane people is a wholesome path to tread. Atherosclerosis and heart disease are not inevitable results of aging. They can be avoided through healthy life choices.
Diets high in whole, unprocessed carbohydrates support superb heart health.
Diets low in fats of all kinds but especially saturated fat promote healthy arteries.
Movement is essential to thriving, so much so that humans should strive to spend most of their waking hours in motion.
Maintaining an optimal body weight is important for a robust life.
If meat is eaten it should be partaken in small amounts. Wild animal meat sources are far preferable to domestic ones.
Smoking should be avoided.
Lead scientist of the Tsimane study, Professor Hillard Kaplan, sums it up this way. “Their lifestyle suggests that a diet low in saturated fats and high in non-processed fibre-rich carbohydrates, along with wild game and fish, not smoking and being active throughout the day could help prevent hardening in the arteries of the heart. The loss of subsistence diets and lifestyles could be classed as a new risk factor for vascular ageing and we believe that components of this way of life could benefit contemporary sedentary populations.” (2)
2 Kaplan, H., Thompson, R.C., Trumble, B.C., Wann, L.S., Allam, A.H., Beheim, B., Frohlich, B., Sutherland, L. et al. Coronary atherosclerosis in indigenous South American Tsimane: a cross-sectional cohort study. The Lancet April 2017; 389 (10080): 1730–1739.
3 Budoff, M.J., Young, R., Lopez, V.A., Kronmal, R.A., Nasir, K., Blumenthal, R.S. et al. Progression of coronary calcium and incident coronary heart disease events: MESA (Multi-Ethnic Study of Atherosclerosis). J Am Coll Cardiol. 2013 Mar 26; 61(12):1231-9.
4 Blaha, M.J., Cainzos-Achirica, M., Greenland, P., McEvoy, J.W., Blankstein, R., Budoff, M.J>, Dardari, Z. et al. Role of Coronary Artery Calcium Score of Zero and Other Negative Risk Markers for Cardiovascular Disease: The Multi-Ethnic Study Of Atherosclerosis (MESA) Circulation. Circulation. 2016 Mar 1; 133(9): 849–858.
6 Gurven, M., Jaeggi, A.V., Kaplan, H., Cummings, D. Physical activity and modernization among Bolivian Amerindians. PLoS One. 2013; 8:e55679.
7 Matthews, C.E., Chen, K.Y., Freedson, P.S., et al. Amount of time spent in sedentary behaviors in the United States, 2003-2004. Am J Epidemiol. 2008; 167: 875–81.
8 Martinm M,A,, Lassek, W.D., Gaulin, S.J., Evans, R.W., Woo, J.G., Geraghty, S.R., Davidson, B.S., Morrow, A.L., Kaplan, H.S., Gurven, M.D. Fatty acid composition in the mature milk of Bolivian forager-horticulturalists: controlled comparisons with a US sample. Matern Child Nutr. 2012 Jul; 8(3):404-18.
10 Clarke, E.M., Thompson, R.C., Allam, A.H., Wann, L.S., Lombardi, G.P., Sutherland, M.L., Sutherland, J.D., Cox, S.L. et al. Is atherosclerosis fundamental to human aging? Lessons from ancient mummies.
J Cardiol. 2014 May; 63(5):329-334.