Reprinted online July 2008

Heart disease is – perhaps more than most others – a disease of modernization. From increasing inactivity to worsened dietary and environmental quality, many factors contribute to this condition in modern societies. Anthropologists look at this disease in its total context from cultural to biological factors. In this review, I will focus on body mass and obesity as significant risk factors for heart disease and their evolution in developing societies. I describe in detail findings from a recent article in Human Biology (Reddy 1998) on this topic. I also discuss some additional risk factors including poor air quality and migration. In addition, I look at various anthropological solutions to this and related disorders including pharmaceuticals derived from natural sources used for stroke and meditation.

Body Mass and Socioeconomic Status
Reddy looked at more than 1,000 people – both male and female, age 18 to 75 years – in a socio-economically diverse region called Andhra Pradesh, India. She noted that body mass index (BMI), an indicator of body mass, increased with age to age 50 and then declined, and also increased with socioeconomic status and decreased physical activity level. In more urban people and those with higher income and reduced physical activity levels, obesity levels increased. The prevalence of obesity (BMI over 25) is 6.6% in males and 10% in females. Previously Reddy (1998) discovered that high BMI increased risk of cardiovascular disease in this same population.

Occupational specialization in complex societies contributes to heart disease risk by limiting physical activity levels and optimal nutrition among certain parts of society. In India, the traditional caste system also increases this division of labor. Reddy drew her sample from seven castes of varying social status and a traditional semi-nomadic tribe (the Yerukala). The castes and the tribe were categorized into four groups, including the traditional semi-nomadic tribe (the Yerukala) (Group One), hard-working agricultural and other laborers of the Mala caste and Muslims (Group Two), the land-owning agriculturists castes, Reddy and Balija (Group Three), and urban, sedentary Brahmin, Vyshya, and Marwadi (Group Four). Group Four (Brahmin, Vyshyas, and Marwadis) is urban and works in government service or in business, while Groups one and two are rural, and Group Three is semi-rural. The Group One Yerukala tribe is semi-nomadic and treks around between villages with herds of pigs, living in tents. They primarily beg for food since all of their traditional foraging resources have been eliminated by agriculture. Group Two people are from the lower castes and depend on hard physical labor for income.

Anthropometric variables were assessed and physical activity was classified according to three categories: heavy, medium, and light. The former was used for farm laborers, rickshaw pullers, and washermen, while shopkeepers, landowners, servants, and housewives made up the medium level, and professionals made up the light level. Groups Three and Four (more affluent) consumed more fatty foods and oils, dairy products, and protein (mostly vegetarian protein sources, such as lentils, since all groups were largely vegetarian). Groups Three and Four also consumed more leafy vegetables. Statistical analysis was performed using SPSS software. Although only about two percent of the adult males in the hard working rural groups, one and two were found to be obese, eight percent of males of the land-owning agriculturist Group Three and 14% of males of the most affluent Group Four were found to be obese. For females, these proportions were similar for the first three groups, but 24%, compared with 14% in males, were found to be obese in the affluent Group Four. This frequency is as high as that found for the US population (Van Itallie 1985). Ironically, in India, the vegetarians, who make up most of Group Four, are more obese than the non-vegetarians (Groups One to Three). However, this is due to their more sedentary lifestyle and a diet richer in fats and oils than a vegetarian diet. A high fat intake may be conducive to weight gain through its effect on metabolic rate (Flatt 1978; Achenson et al. 1984; Swaminathan et al. 1985). In addition, the non-vegetarian groups are really semi-vegetarian since they consume meat and fish very infrequently.

Obesity and heart disease risk is a double-edged sword in anthropology since, in developing societies, the rich get fatter while the poor get thinner. Many subjects in Groups One and Two suffered from chronic energy deficiency (CED) and inadequate household food supply: 53% of adult males and 40% of adult females suffered from some form of CED in Groups One and Two, while only 18% and 36% suffer from it in Group Three, and 25% and 19% in Group Four, respectively. Persistence of CED in about 20% of the adult population of even the most affluent Group Four is typically characteristic of developing nations. Naidu and Rao (1994) noted that in Indian rural populations, CED is of primary significance rather than obesity or overweight, as is the case in Western populations. Men are particularly at risk for CED since they do most of the hard physical labor in India.

Another interesting finding of this study has been echoed in many previous ones as well: women are more susceptible to obesity than men. Age is more strongly associated with BMI in females than in males. The enhanced association between age and BMI in females is thought to be an artifact of cumulative impact of pregnancies (Noppa and Bengtsson 1980), because some of the weight gained during pregnancy may be retained. That the significant association between BMI and age is characteristic only of the two affluent Groups Three and Four and not of the rural groups confirms de Vasconcellos' (1994) observation among Brazilians that BMI decreases with age in rural areas and increases with age in urban areas.

In contrast to the positive association between socioeconomic status and BMI in developing countries, modern Western populations show a negative association between these variables (Van Itallie 1985; Forman et al. 1986; Garn 1986; Shah et al. 1989; Khan et al. 1991; Croft et al. 1992; Gortmaker et al. 1993; Randrianjohany et al. 1993; Stunkard and Sorensen 1993). Anthropologists suggest that this is due to the fact that the industrialized Western populations experienced the effects of a protein and fat-rich diet and a subsequent rise in cardiovascular deaths. As a result of this experience, the more literate upper strata of the population began to eat a more balanced diet, consciously avoiding food items that may contribute to obesity and high cholesterol levels. They also began to exercise during their leisure time.

Other researchers have discovered patterns similar to Reddy's. Shah et al. (1989) found that occupation and income are the most important determinants of BMI in males, whereas in females, alcohol intake, caffeine intake, and race are the key variables. De Vasconcellos (1994) studied BMI in Brazil and found that low BMI is also related to low income in this country. Delpeuch et al. (1994) note that in the Congo, a central African country, high BMI is an urban phenomenon while low BMI occurs in rural areas. In India, Naidu and Rao (1994) note that landless agricultural laborers and other low-income groups have a lower BMI than cultivators, artisans, and high-income groups. In southern West Bengal, Bharati (1989) noted that BMI is related to socioeconomic status and Sanjeev et al. (1991) also note that no lower socioeconomic status individuals are in the overweight category, whereas 12.1% of upper socioeconomic status subjects were overweight or severely overweight.

What does this mean for people in industrial societies? Put simply, given the long-term relationship between high BMI and high social status in traditional societies, we can understand the difficulty we experience in losing body mass in order to reduce risk of heart disease. "Bigger" people appear to be wealthier and of higher status to us since that is often the situation in developing societies. As a result, we try to "be big" with disastrous effects on our health.

Air Quality
With increased urbanization, air quality is worsened, which may result in higher risk of heart disease. For example New York City (NYC) residents' unusually high rate of ischemic heart disease (IHD) results from chronic exposure to that city air among other factors. One recent study used all US death certificates for 1985-1994 to examine (correcting for age, race, and sex) IHD deaths in three groups: NYC residents who died in the city, non-NYC residents visiting the city, and NYC residents traveling out of the city. The researchers found that IHD deaths among NYC residents dying in the city were 155% of the expected proportion. Among visitors to the city, such deaths were 134% of the expected proportion. The proportion of IHD deaths among NYC residents dying out of the city was only 80% of the expected value. These effects are not due to nearby commuters, recent immigrants, local classification practices, or socioeconomic status, and they do not appear in other US cities. With both chronic and acute effects of exposure to NYC air, these data are consistent with the hypothesis that the stress of NYC is linked to the high rate of IHD.

Migration
Increased migration is an important aspect of developing and developed societies. With additional transportation technologies, it becomes easier for people to move from one location to another. However, it appears that this migration can increase risk of heart disease. Studies by Cassel (1970: 196-198) and associates show that people who move farthest away from their childhood class level and place of residence have the highest rate of heart disease. Epidemiological correlations have been found between geographic mobility and coronary heart disease in North Dakota (Syme: 1964) and North Carolina (Tyroler and Cassel: 1964), especially where cultural discontinuity occurs, such as changes from rural to urban environments. (Mausner and Bahn: 1985)

Natural Products
Other anthropological studies are looking at how certain ethnopharmaceuticals can help prevent or treat cardiovascular disease or stroke. For example, a blood-thinning drug derived from the venom of the Malayan pit viper can reverse symptoms in stroke victims, researchers reported recently in the Journal of the American Medical Association. The experimental treatment follows the discovery that blood failed to clot in people bitten by the snake. Scientists figured the venom could be used as an anticoagulant to help stroke victims who have a clot that is blocking blood flow to the brain. In a study of 500 stroke patients, 42% who were given the drug Ancrod within three hours after the onset of symptoms regained significant functioning vs. 34% of those who got a placebo. The study was led by Dr. David Sherman, a neurologist at the University of Texas Health Science Center in San Antonio, and was conducted in the United States and Canada. The promising results led Ancrod's manufacturer, BASF Pharma, to launch a separate European study to see if it would also work within six hours of symptoms. Ancrod is similar to the clot-buster TPA, the only federally approved drug for strokes. TPA dissolves clots, while Ancrod lowers blood levels of fibrinogen, a substance that can help form clots. That allows blood to flow more freely. Both drugs are given intravenously. TPA, like Ancrod, has a three-hour treatment window. About 700,000 Americans have strokes each year. Many end up with paralysis, impaired speech, and other debilitating effects. Until the recent use of TPA, there was little doctors could do to treat strokes once symptoms such as numbness and difficulty speaking appeared. BASF Pharma keeps a colony of snakes in Germany and milks them regularly to extract the venom, which is necessary since no synthetic version has been synthesized yet.

Meditation
Numerous traditional practices, such as meditation, are being tapped to help people fight heart disease. A growing body of research shows that meditation reduces heart rate and blood pressure, improves immune function, and decreases stress-hormone levels. Meditation focuses on making a shift from thinking and planning to just being. Techniques emphasize learning to avoid worrying or replaying negative thoughts, also called mind chatter or mental turbulence, which raises stress hormone levels and limits the ability to enjoy life. In one study, people who performed transcendental meditation every day for three months had a drop in systolic pressure that was ten points greater than the drop in people who were counseled on lifestyle changes such as losing weight, reducing dietary salt, exercising, and reducing alcohol intake. The meditators' diastolic pressure dropped by approximately six points more than subjects in the advice-only groups did. Meditation may work by reducing stress, and so it can help people curb unhealthy behaviors such as overeating or drinking too much alcohol. In studies, people who were counseled to make lifestyle changes made few alterations in their day-to-day habits, but the meditation groups went from roughly 11 drinks a week to five, indicating that meditation may make it easier for people to implement other healthy changes. What's more, while blood pressure drugs including diuretics, calcium channel blockers, and ACE inhibitors can lead to a rise in blood cholesterol, impotence, fatigue, dry mouth, nasal congestion, diarrhea, nausea, headache, and dizziness, meditation has no side effects.

Bathing
While warm baths are thought to be potentially dangerous for heart patients in Western cultures, Japanese doctors routinely prescribe them as heart disease therapy. Now, findings from a small study suggest that warm baths improve exercise endurance in the elderly, regardless of whether they are heart patients or healthy people. Ten minutes of soaking boosted performance on the treadmill and improved fatigue and leg pain among 16 elderly men and women, some who had heart disease and some who did not, according to researchers from Kagoshima University in Japan. Dr. Megumi Shimodozono and his colleagues presented their findings at a recent annual meeting of the American Academy of Physical Medicine and Rehabilitation. Study co-author Dr. Nobuyuki Tanaka explained that it is widely believed heart disease patients should avoid warm baths because they may speed the heart rate. However, according to Tanaka, warm baths are safe for the heart and dilate blood vessels and thus allow more blood to get to the muscle. A short dip of ten minutes in a 41-degree Celsius (106°F) bath was used in the study. Other anthropological studies show that people in traditional societies have larger hearts and better cardiovascular performance than industrial people. Similarly wild rabbits have larger hearts and better cardiovascular performance than domesticates.

Conclusion
To wrap up, anthropological research is showing that heart disease and the closely related risk factor of obesity are deeply intertwined with our cultural and evolutionary environment. Through various means, we are conditioned, in developed and developing countries, to consume infinitely, which encourages obesity and cardiovascular disease. At the same time, traditional societies offer important clues for ways to prevent and fight heart disease, from new drugs developed through studies of traditional medicine to meditation, relaxation, exercise, and even hydrotherapy.

About the Author
Tim Batchelder, BA, is a communications consultant who specializes in the anthropology of science and technology.

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