The Influence of Religion on Health
The Relationship between Spirituality and Health
The research investigating the influences of spirituality and various Eastern religious practices, such as yoga or various types of meditation, is extensive (Seeman, Fagan-Dubin & Seeman, 2003). Many of these studies look into the relationship between meditation and various physiological measures. Because the literature is so extensive, only some representative studies will be cited here. The most documented relationship is the influence of meditation on blood pressure (Patel et al., 1985; Sudsuang, Chentanez & Veluvan, 1991; Schneider et al., 1995; Schmidt, Wijga, Von Zur Muhlen, Brabant & Wagner, 1997). In a randomized, longitudinal study, the influence of meditation/relaxation techniques on the incidence of cardiovascular disease (participants were judged as being at high risk for it if they had two or three of the following risk factors: smoking, high blood pressure and high cholesterol) was investigated (Patel et al., 1985). Results showed that at eight weeks, eight months and four years afterwards, the participants that followed the meditation/relaxation techniques program had a significantly lower blood pressure. A second study involving a randomized design looked at the influence of transcendental meditation and progressive muscle relaxation on blood pressure in a sample of older African American adults (Schneider et al., 1995). The group in the transcendental meditation condition showed reduced systolic and diastolic pressure significantly more (almost twice) than the group in the progressive muscle relaxation, and the group in the life-style education classes. This study is very interesting considering the sample used. Most of the studies usually use White or Asian, male, college students as participants. However, an important issue of these studies is that they did not address meditation as a religious/spiritual practice.
Another study compared a group of individuals from a residential area in Sweden participated in a three-month yoga and meditation training program with a group of individuals from a residential area in Germany that did not participate in the program (Schmidt et al., 1997). The Swedish participants showed decreased blood pressure following the three months program (especially those with elevated levels) compared to the German participants. Finally, a group of male college students that followed a Dhammakaya Buddhist meditation program showed a reduction in systolic and diastolic pressure, compared to a control group of male college students that did not follow the program (Sudsuang et al. 1991).
This last study also showed that the college students following the meditation program had lower stress hormone levels (specifically cortisol) at the end of the program (Sudsuang et al., 1991). Another study that also looked at cortisol levels in a control group of young adults, this same group after 3-4 months of practicing transcendental meditation, and another group, of long-time (3-5 years) practitioners of transcendental meditation (Jevning, Wilson & Davidson, 1978). For the control group, the levels of cortisol did not change, while for the short-term practice of meditation, the levels decreased but not significantly. For the long-term practitioners, however, the cortisol levels deceased significantly and remained like that after the sessions of meditation. In addition, Walton, Pugh, Gelderloss and Macrae (1995), in a cross-sectional study, investigated the differences in the levels of various hormones and minerals between healthy, young adults who did not practice any stress-reducing technique and a similar group that had practiced transcendental meditation for a long time. The latter group showed lower levels of cortisol, aldosterone and norepinephrine. One other study analyzed levels of cortisol, β-endorphin and adrenocorticotropic hormone (ACTH) in two groups: one of practitioners of transcendental meditation and another of non-practitioners (Infante et al., 1998). Results showed that the meditation practitioners had no diurnal rhythm for ACTH and for β-endorphin, as compared to the control group. However, a methodological issue of the last three studies is that they did not make use of randomization, relying on data from groups of individuals that had already practiced or not meditation (Seeman et al., 2003). Ironson et al. (2002) found that private religious and spiritual feelings were associated with long survival in HIV-positive and AIDS patients, and the having a general sense of peace was strongly related to lower levels of cortisol, and thus showing that physiological benefits might come from non-organized spiritual beliefs.
The effects of stress reduction through transcendental meditation were studied in another study that looked at the relationship between meditation and oxidative stress (Schneider et al., 1998). Levels of lipid peroxide were measured in elderly adults, some of whom were long-term practitioners of transcendental meditation and others who were not. The practitioners of meditation showed lower levels of lipid peroxide compared to the control group. However, this study had the same methodological problem: it does not use randomization. In addition, there seem to be no other studies that look at this association and thus more research is needed in this area. Moreover, some of the studies presented above have also looked the relationship between meditation and levels of cholesterol (Patel et al., 1985; Schmidt et al., 1997). The first of these studies, cholesterol levels were lower after eight weeks and eight months but not after four years for the participants that engaged in meditation and relaxation techniques (Patel et al., 1985). The second study showed that participants in a three-month yoga and meditation program had a lower total serum and LDL cholesterol after the training (Schmidt et al., 1997).
The literature on spirituality and Eastern religious practices is extensive. From the studies cited here, some evidence for the existence of a relationship between meditation and health exists. Specifically, the relationship between mediation/relaxation techniques and blood pressure seem to have the strongest evidence (Seeman et al., 2003), while the other relationships between meditation/relaxation techniques and stress hormones, oxidative stress and cholesterol have some evidence but not as strong, due to methodological issues (Seeman et al., 2003).
The Relationship between Religion and Health
Other studies have looked into the relationship between religion/religious practices and health. Many of these studies have focused on Judeo-Christian practices, specifically synagogue/church attendance and/or prayer (Seeman et al., 2003), and only few studies have looked into Islamic practices. The most pervasive associations are between religious practices and lower blood pressure, better lipid profiles, better immune function, and lower all-cause mortality (Seeman et al.).
The first of the studies investigating the link between religious practices and blood pressure used a large sample of older adults with high blood pressure and/or taking medication for high blood pressure (Koenig et al, 1998). Data was collected in three stages, over a period of eight years. Analyses were controlled for age, race, gender, education, body mass index, physical functioning, and blood pressure from previous stages, and revealed small (1-4 mm Hg) but consistent differences between people who attended religious services, prayed and studied the Bible frequently and those who did these activities infrequently. In addition, people who frequently attended these religious practices were more likely to take their medication, although this did not account for the differences in blood pressure. However, these findings did not extend to people who were just frequently watching religious TV or listened to religious radio (Koenig et al., 1998). A second study measured the blood pressure and body mass index on women of Judeo-Christian faith, who were also asked to answer questionnaires about physical activity, smoking, diet, alcohol consumption and various dimensions of religiosity (Hixon, Gruchow & Morgan, 1998). After multiple regression path analyses were conducted to determine the effects of religiosity on blood pressure (with the body mass index and age controlled), religiosity was found to have an effect on blood pressure via a more direct pathway, such as the ability to cope with stress. A third study looked at the ambulatory blood pressure in a sample of both men and women, Blacks and Whites, over the time of a workday (during sleep and wake) (Steffen, Hinderliter, Blumenthal & Sherwood, 2001). Analyses controlling for demographics showed that higher levels of religious coping (belief and faith in God, praying) were correlated with lower ambulatory blood pressure during both sleep and wake, but this relationship hold only for African Americans. Another study that looked at this relationship evaluated a large, representative sample of Muslims (both Sunni and Shiite) from Kuwait (Al-Kandari, 2003). The religiosity of the participants was measured through considering not only mosque attendance but also praying five times a day, giving alms, extra praying, daily reading and listening to readings of the Qur’an, fasting and going on pilgrimage to Mecca. After controlling for social support and network, body mass index, smoking, SES, gender and age, religious commitment was found to be associated with lower blood pressure (Al-Kandari, 2003).
Related to the relationship between religion/religious practices and blood pressure is the relationship between religion/religious practices and cardiovascular disease. Research on this topic provides evidence for the protective role of religion against cardiovascular disease (Powell, Shahabi & Thorensen, 2003). Colantonio, Kasl and Osfeld (1992) analyzed the influence of different psychosocial factors (religiousness, marital status, social support, social networks and depression) as predictors of stroke incidence through a longitudinal study on elderly people. The results showed that more frequent attendance at religious services was associated with lower stroke incidence (Colantonio et al., 1992). Two other studies use large, representative samples of American adults (coming from a Judeo-Christian background), followed for a long period of time (Hummer, Rogers, Nam & Ellison, 1999; Oman, Kurata, Strawbridge & Cohen, 2002). Among other relationships, they both looked at the relationship between religion (specifically religious services attendance) and cardiovascular mortality, and showed that frequent religious services attendance lowered the risk of cardiovascular mortality.
Immune function was also investigated, in relationship with religious practices. An interesting study analyzing the data from a sample of HIV-positive gay men showed that religious behavior (e.g. service attendance, prayer, reading religious literature) was significantly associated with higher CD4+ (T-helper-inducer cell) counts and percentages (Woods, Antoni, Ironson & Kling, 1999). Another study that looked at the relationship between religion and immune function, analyzed a sample of women with metastatic breast cancer (Sephton, Koopman, Schaal, Thorensen & Spiegel, 2001). Again, religion was evaluated through the frequency of religious services attendance and the importance of spiritual expression in their lives. After controlling for demographic, disease status, and treatment variable, women who rated spiritual expression as more important had greater numbers of circulating white blood cells and total lymphocite counts (both helper and cytotoxic T-cell counts included). Finally, Koenig et al. (1997) used a large sample and both cross-sectional and longitudinal data on religious attendance. The findings pointed to a significant association between high church attendance and lower levels of interleukin-6 (a marker of inflammation) but only for the cross-sectional data.
Four articles also found a relationship between religiosity and lipids in Orthodox Jews, Orthodox Christians, and Muslims, which is very interesting, considering the sparse literature available on some of these populations. The first two articles compare Orthodox adult Jews with secular individuals, and found that the former had lower total cholesterol, triglyceride, and LDL cholesterol levels (Friedlander, Kark, Kaufmann & Stein, 1985) and the same differences between orthodox and secular adolescents (Friedlander, Kark & Stein, 1987). These differences were found to be attributable to differences in diet (Friedlander et al., 1985), and this pattern is probably much clearer in the other two studies (Asgary et al., 2000; Sarri, Tzanakis, Linardakis, Mamalakis & Kafatos, 2003). The first of these two studies analyzed lipid peroxidation before and after the month of Ramadan, when the Muslims fast (abstaining from any food) from sunrise to sunset (Asgary et al., 2000). Only men were included in the study. The results showed that triglyceride, cholesterol and malondialdehyde (one product of lipid peroxidation) levels decreased significantly during Ramadan. However, this study was very limited because of its unrepresentative sample (only men) and because of its short time-period. A longitudinal study, analyzing the data over a period of years and comparing individuals who were fasting during those years with individuals who did not fast would be a more telling study. The second, groundbreaking study analyzed the impact of Greek Orthodox Christian fasting on lipoproteins (Sarri et al., 2003). A sample of Greek adults who fasted regularly (40 days before Christman, 48 days before Easter and 15 days before the Assumption) were followed for one year and compared to a similar sample that did not fast. Results showed that total and LDL cholesterol were significantly lower in people who fasted as compared to those who did not fast. Although this study had a more representative sample, it was too short in length of time. Because Orthodox fasting spreads throughout the year, a period of several years is again needed for a more complete and reliable analysis. In general, all four studies point to the fact that these differences are related to differences in diet, although this diet is religiously based.Continued on Next Page »