Between first and second generation US immigrants, a striking increase in overweight and obesity occurs.  A study using data from the National Longitudinal Study of Adolescent Health set out to determine the underlying factors that cause this phenomenon.  More than 8,600 adolescents of varying ethnicity were assessed for overweight and several factors including diet.  Researchers concluded that immigrant adolescents are likely to be influenced by the “obesigenic” environment of the US, including sedentary lifestyles, large portion sizes, heavy advertising of high-fat, energy-dense foods, and mass media.  Lifestyle differences between foreign- and US-born Hispanic adolescent immigrants are likely to underlie the striking increase in overweight between first and subsequent generations of US residence.
Social Science & Medicine, April 2003; 57:2023–2034 (Gordon-Larsena P et al.)

In an effort to track the rise in chronic disease among people who move away from their traditional diets, scientists at Tufts University synthesized data about diets and health from many sources. They found a close association between dietary change (starting with the rich) and the health impacts of a more processed, energy-dense diet.
Cadernos de Saúde Pública. 2003; 19 suppl 1:S87-99. (Bermudez et al.)

University of Guelph researchers in Ontario, Canada found that amaranth can be a rich dietary source of phytosterols, which have cholesterol-lowering properties.  Of the four varieties tested, the top results came from Amaranthus K343, often called Plainsman, the most commonly cultivated amaranth in the United States.
Plant Foods for Human Nutrition, 2003; 58(3):207-11
 

Australian researches conducted a study focusing on Greeks who relocated to Melbourne but maintained their traditional Mediterranean diet.  During this study, the foods selected for nutrient evaluation – leafy green vegetables, figs in season, and various types of olive oil – were those commonly consumed by Greeks living in Melbourne, but not by native Australians.  Of all the commercial and wild leafy greens studied, amaranth leaves were found to contain some of the highest levels of beta-carotene and lutein, even higher than the commercially available chicory and endive.
European Journal of Clinical Nutrition, November 2002; 56(11):1149-54

Researchers from Oxford University studied a large cohort of British men and women in the context of diet, lifestyle, and disease risk. They found that hypertension (both systolic and diastolic) is significantly less prevalent among vegan men and women (5.8% and 7.7%, respectively) as compared to omnivorous men and women (15.0% and 12.1%, respectively). The researchers suspect that this is related to the vegan participants’ lower average Body Mass Index.
Public Health Nutrition. 2002 Oct 1;5(5):DOI 10.1079/PHN2002332. (Appleby et al.)

Barley varieties such as Prowashonupana that are especially high in beta-glucan fiber may digest more slowly than standard barley varieties. Researchers at USDA and the Texas Children’s Hospital compared the two and concluded that Prowashonupana may indeed be especially appropriate for obese and diabetic patients.
Journal of Nutrition, September 2002; 132(9):2593-6

Researchers at Colorado State University randomly assigned thirty-six overweight middle-aged men to eat either an oat or wheat cereal daily for twelve weeks. At the end of the three-month period, the men eating the oat cereal had lower concentrations of small, dense LDL cholesterol (thought to be particularly dangerous) and lower LDL overall, compared to those in the wheat group, while their HDL (“good”) cholesterol was unchanged.
American Journal of Clinical Nutrition, August 2002; 76(2):351-8

Researchers from the London School of Hygiene and Tropical Medicine compared the diets of 240 South Asian women who had breast cancer with age-matched South Asian women who did not. They found that there was a slight reduction in the risk of breast cancer among women who identified as lifelong vegetarians compared with those who identified as lifelong meat-eaters. The researchers believe that reduction in the risk of breast cancer among lifelong vegetarians is most likely related to increased consumption of vegetables and pulses (legumes).
International Journal of Cancer. 2002 May 10. 99, 238-244. (dos Santos Silva et al.)

Using a randomized, controlled parallel-group pilot study, researchers followed 18 hypertensive and hyperinsulemic men and women for six weeks, while half of them ate oat cereal (5.52g/day of beta-glucan) and the others ate a lower-fiber cereal (less than 1g total fiber). The oat group enjoyed a 7.5mm Hg reduction in systolic blood pressure and a 5.5 mm Hg reduction in diastolic blood pressure, while the wheat group was unchanged.
Journal of Family Practice, April 2002; 51(4):369

The dietary intake in Thailand has changed dramatically over the last 30 years, with a trend toward increased consumption of animal fat, animal meat and convenience foods, and decreased consumption of Thai staples and side dishes.  The prevalence of childhood and adolescent obesity in Thailand is increasing, and adults are facing increased incidence of chronic disease. Today, diet-related chronic degenerative diseases are the leading cause of death in Thailand.
Public Health Nutrition. 2002 Feb;5(1A):183-9.  (Kosulwat V.) 

This study at Emory University reported on Eat for Life, a health intervention initiative to increase fruit and vegetable consumption among African Americans. Fourteen black churches were randomly assigned to give various levels of intervention and support to participants. One group received a one-time motivational health counseling call, while another group received a series of health counseling calls, enjoying ongoing motivational support. In a follow-up after 1 year, fruit and vegetable intake was assessed by three food frequency questionnaires. Change in fruit and vegetable intake was significantly greater in the group that received several counseling calls than in the group that received only one. Ongoing counseling support appears to be an effective strategy for helping people change the way they eat, and Black churches are an excellent setting to provide and evaluate health promotion programs. 

American Journal of Public Health. October 2001, Vol 91, No. 10: 1686-1693. (Resnicow et al.)

Africans carried their foods and dietary customs into diaspora throughout the Americas as a result of the European slave trade. Their descendants represent populations at different stages of a nutrition transition. West Africans are more often in the early stage, where there are many challenges and conditions like undernutrition and nutrient deficiencies. Many Caribbean populations represent the middle stages, with undernutrition and obesity co-existing. African Americans and black populations in the United Kingdom suffer the worst, from the consequences of caloric excess and diets high in fat and animal products. Obesity, diabetes, high blood pressure, coronary heart disease, and certain cancers are prevalent in the African-American and Afro-British populations, and they are beginning to emerge in populations that never before faced these diseases, as diets become more Western.

Annual Review of Nutrition, 2001;21:47-71. (Luke et al.)