What can we learn about diet and heart health from (East) Asian emigrants?

1. What can we learn about diet and heart health from (East) Asian emigrants? Presented to Pulse of Asia Daegu, Korea April 17, 2009 By Ted Greiner, Professor of Nutrition Dept of Human Ecology, Hanyang University Seoul, Korea

2. Not enough! • The amount of research that has been done appears to me inadequate to answer many of the questions we might want to ask • I will review a few of what seem to be to be fairly clear findings and hypotheses • I will also present some findings, both from the literature and from my own students’ work (Chinese and Mongolians studying in Sweden) that often seem to raise as many questions as they answer

3. Do immigrants copy behavior of the host population? • Kockturk, who studied breastfeeding among immigrants to Sweden did not think so • She hypothesized that they copy what they assume is the behavior of rich people in their home country • But a later study of Bangladeshi immigrants to Sweden Rehana suggested that the truth may often lie somewhere in between: they breastfed longer than Swedes but more exclusively than Bangladeshis in the early months

4. It is unclear whether: • Ethnic group variation occurs in acculturation-health relationships • Acculturation components vary differently in relationship to health • Biculturalism has beneficial effects on health* *Quoted from Lee et al. Acculturation and health in Korean Americans. Social Science & Medicine 2000;51: 159-173.

5. Chinese ethnic immigrants have better heart health • Ethnic Chinese immigrants to Canada had lower age-standardized death rates from cardiovascular and ischemic heart disease and congestive heart failure for both genders • All these rates were higher in Canadians, South Asian immigrants and other immigrants (and similar to each other)* *Sheth T, et al. Cardiovascular and cancer mortality among Canadians of European, south Asian and Chinese origin from 1979 to 1993: an analysis of 1.2 million deaths. JAMC 1999;161(2):132-138

6. Chinese ethnic immigrants have better heart health • Thus there was little if any “healthy migrant” effect. • Death rates were not lower in Chinese for cerebrovascular disease. • Findings were similar to those from USA and China • The Chinese had low serum cholesterol levels (4.1 mmol/L)

7. Why is immigrant health better? • The standard hypothesis is that immigrants enjoy better heart health mainly for the first generation. • As they adopt the lifestyle of their new country, their patterns of health change to become like that of the host country.* • Major factors that would confound this include intergenerational maintenance of home-country dietary patterns and genetic factors. *Time travel with Oliver Twist--towards an explanation for a paradoxically low mortality among recent immigrants. Razum O, Twardella D. Trop Med Int Health. 2002 Jan;7(1):4-10.

8. Does East Asian immigrant heart health worsen in the West? • The incidence of myocardial infarction was half that in Japanese in Japan than in Hawaii and 50% greater in California (CA) than in Hawaii.* • Among Chinese in CA, cholesterol was no higher in those born in CA, than those born in China, but BMI and hypertension in men were higher; smoking was lower in men but higher in women.** *Robertson TL et al. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California. Incidence of myocardial infarction and death from coronary heart disease.Am J Cardiol. 1977;39(2):239-43. **Klatsky AL, Armstrong MA. Cardiovascular risk factors among Asian Americans living in northern California. Am J Publ Health. 1991;81(11):1423-8.

9. Mechanisms of change • High consumption of fish, soy, seaweed and vegetables may protect heart health and may explain why Okinawans are better off than other Japanese, both at home and abroad.* • Chinese in N America ate more fruit and vegetables when living with older Chinese--who strongly prefer Chinese food. Younger, working Chinese felt there was no difference in how healthy Chinese diets are and found them inconvenient to prepare.** *Yamori Y et al. Implications from and for food cultures for cardiovascular diseases: Japanese food, particularly Okinawan diets. Asia Pac J Clin Nutr. 2001;10(2):144-5. **Satia-Abouta J et al. Psychosocial Predictors of Diet and Acculturation in Chinese American and Chinese Canadian Women. Ethnicity and Health 2002;7(1):21-39.

10. How about emigrants TO East Asia? • I only found one relevant study, which compared local ethnic Chinese in Singapore with local South Asians (SA) and Malays (M) • Chinese had lower death rates (age 30-69) for ischemic heart disease and hypertensive disease (for each sex) but not cerebrovascular disease* • The Chinese had the lowest prevalence of diabetes and the lowest rate ofcigarette smoking • Malays had higher blood pressure • South Asians had lower high density lipoproteins** *Hughes K, et al. Cardiovascular diseases in Chinese, Malays, and Indians in Singapore. I. Differences in mortality. J Epidem Comm Health. 1990;44(1):24-8. **Hughes K, et al. II. Differences in risk factor levels. J Epidem Comm Health. 1990;44(1):29-35.

11. Koreans who moved to the USA • Based on careful theoretical work and examining degree of acculturation better than most have done, Lee et al* studied Koreans who moved to the USA • Regarding the impact of immigration on health, very few clear relationships emerged. (Most observed relationships seemed quite complex.) *Lee et al. Acculturation and health in Korean Americans. Social Science & Medicine 2000;51: 159-173.

12. Koreans who moved to the USA • Only about half got even light exercise regularly • 27% of men and 9% of women were current smokers • The mean BMI was 24 for men and 21 for women • Fat intake was not related to acculturation

13. Koreans who moved to the USA • The more acculturated men were heavier but reported being more healthy • But we are uncertain of their definition of health • And Koreans have not been living in the USA for as long as other immigrant groups

14. Do ethnic East Asians respond differently to risk factors? • Serum cholesterol is a risk factor in Chinese in China, even when levels are quite low by Western standards* • The increased incidence of heart disease among Japanese living in Hawaii compared to Japan had the usual risk factor associations: systolic blood pressure, serum cholesterol, relative weight and age • Smoking was an exception (not a risk factor)** *Chen Z, et al. Serum cholesterol concentration and coronary heart disease in population with low cholesterol concentrations. BMJ. 1991;303(6797):276-82. **Robertson TL et al. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California. Coronary heart disease risk factors in Japan and Hawaii. Am J Cardiol. 1977;39(2):244-9.

15. Complex genetics is sometimes involved • Canadian South Asian (SA) immigrant patients in rehab for coronary artery disease (and not taking B vitamins for one mo) had similar levels of plasma homocysteine (PH) to Canadians, but East Asian (EA) patients’ levels were lower (1/5 as many were abnormal (PH > 12 μmol/l)).* *Senaratne et al. Possible Ethnic Differences in Plasma Homocysteine levels associated with coronary artery disease between South Asian and East Asian immigrants. Clin Cardiol 24,730-734 (2001).

16. Complex genetics is sometimes involved Lipid subfractions, diabetes and hypertension levels were similar Vegetable intake was higher in SA than EA Thus PH differences could be genetic The relative contribution of PH in relation to the pathogenesis of atherosclerosis in EA patients appears to be negligible

17. Unpublished masters theses from Uppsala • Su Hebate. Dietary acculturation of Chinese residents in Uppsala. Masters thesis, Uppsala University Department of Women's and Children's Health, 2003. • Chen Wen. Cardiovascular disease risk factors in Chinese residents in Uppsala, Sweden. Masters thesis, Uppsala University Department of Women's and Children's Health, 2004.

18. 1. Dietary acculturation of Chinese residents in Uppsala • 76 Chinese residents in Uppsala, Sweden were interviewed; data were complete on 68 • Participants were identified by a modified “snowball” method beginning with a list provided by the Chinese Association in Uppsala • Born in China but lived in Sweden > 3 months; >18 years of age • They were asked only about how their diets changed – no other dietary assessment was conducted

19. Results • The following foods were consumed more in Sweden than had been in China: • cheese (72.1%) • butter (64.7%) • milk (54%) • chicken/poultry (70.6%) • fruit (57.4%) • coffee (61.8%) • potato (48.5 %) • egg (47.1 %)

20. Results, cont • The following foods were consumed less in Sweden than had been in China: • legumes and legume products (89.7%) • animal fat (51.5%) • fatty meat (52.9%) • fish/shellfish (54.4%) • dark green leaves vegetables (85.3%) • other green leafy vegetables (66.2%) • other vegetables (61.8%) • snack food (66.2%) • alcohol (48.5 %)

21. Changes in Factors that influenced dietary habits after coming to Sweden

22. Determinants of Dietary Change • Many statistical tests were performed, so these results need to be interpreted with caution • Very few of the potential associations were statistically significant – only the significant ones are reported here • Women decreased lard consumption more than men (68 vs 35%) • People living with someone else increased consumption of poultry and fruit more than those living alone

23. Determinants of Dietary Change • Those with higher incomes ate more fruit and cheese but less legumes • Those who had lived longer in Sweden increased fruit consumption more • Those who most increased their fruit consumption were more likely to have gained weight after coming to Sweden

24. 2. Cardiovascular disease risk factors in Chinese residents in Sweden • Based on interviews with a sample of 80 individuals aged 18-64 years • Born in China but lived in Sweden > 3 months • Participants were identified by a modified “snowball” method beginning with a list provided by the Chinese association in Uppsala • Height, weight and blood pressure were measured

25. Results • 81.3% thought that cardiovascular disease could be prevented • Risk factors they listed (with no prompting) were: • Fat in food, 58.8% • Lack of exercise, 47.5% • Stress, 31.3% • Smoking, 13.8% • obesity, 7.5% • diabetes, 2.5% • Hypertension, 3.8%

26. Results cont • Risk factors they had: • Smoking, 10%, but none>10 cigarettes/day; another 7.5% quit after arriving in Sweden • Overweight, 11.3% (mean BMI 22.3±2.6) • Obesity, 1.3% • Hypertension, 13.8% (mean SBP and DBP were 116.1±16.4mmHg and 74.9±10.9mmHg respectively) • Free-time physical inactivity, 52.5% • Family history of CVD, 51.3% (37.5% father; 43.8% mother)

27. Determinants • Gender, age, education level, income level, living status and length of stay in Sweden were examined for links with risk factors • The findings are presented in the following slides

28. CV risk factors by gender Gender Male Female n 40 40 % Smoking 15 5 overweight 15 7.5 hypertension* 22.5 5 Physical inactivity 52.5 52.5 family history 47.5 55 mean±SD BMI** 23.2±2.5 21.4±2.5 SBP** 121.6±15.8 110.4±15.1 DBP** 79.0±11.070.8±9.2 Chi-square test for differences in proportions between groups. One-way ANOVA was used to compare means difference between groups.* p<.05; ** p<.01

29. CV risk factors by age Age in years ≤34 35-44 ≥45 N 37 29 14 % Smoking 8.1 10.3 14.3 Overweight* 0 20.7 21.4 Hypertension* 5.4 13.8 35.7 Physical inactivity 59.5 48.3 42.9 Family history 48.9 51.7 51.7 mean±SD BMI** 21.2±1.8 23.0±3.1 23.8±2.1 SBP 114.1±12.0 113.6±13.1 126.3±27.0 DBP* 72.2±8.7 75.1±11.0 81.5±13.7 Chi-square test for differences in proportions among groups. One-way ANOVA was used to compare means difference among groups.* p<.05; ** p<.01

30. CV risk factors by length of stay in Sweden Months 3-12 13-60 61-120 >120 n 24 23 19 14 % Smoking 4.2 8.7 15.8 14.3 Obesity 4.2 13.0 15.8 14.3 Hypertension 12.5 4.3 10.5 35.7 Physical inactivity ´ 41.7 47.8 78.9 42.9 Family history 58.3 39.1 57.9 50 mean±SD BMI 22.6±2.7 21.9±2.5 21.7±2.8 23.3±2.4 SBP 115.8±10.9 114.0±12.9 114.2±18.1 122.5±25.1 DBP 74.6±10.9 72.3±8.1 75.7±10.6 78.6±14.8 Chi-square test for differences in proportion among groups. One-way ANOVA was used to compare means differences among groups.* p<.05; ** p<.01

31. Comparison of risk factors between hypertensives and non-hypertensives Hypertension non-hypertension N 11 69 mean±SD BMI** 25.0±3.4 21.9±2.2 % Overweight 27.3 8.7 Smoking:** Never 36.4 89.9 Former 27.3 4.3 Current 36.4 5.8 Chi-Square test or Fisher’s exact test for the frequencies difference between groups. One-way ANOVA for means differences between groups. *P<0.05; **P<0.01.

32. Is moving to Sweden less harmful to East Asians than moving to USA • There appears to be some evidence for this • Moving to Sweden may have reduced intakes of saturated fats and cholesterol, reduced smoking and heavy alcohol use, increased consumption of fruits (and whole grains), and increased physical exercise • But it may have reduced intake of vegetables, certain types of fish, soy, and seaweed • AND, the data are far too inadequate to say for certain!

33. Thank you! • Full text copies of these two theses and some published papers on obesity in China and Mexico can be downloaded at: http://global-breastfeeding.org/category/obesity/ (Or go to www.global-breastfeeding.org and click on “obesity” on the right side)