Ok so instead of talking about this in a bunch of different thread i'll post what i've found so far on the subject here, and maybe other relevant finds could be share here.
Let's try to go with studies comparing vegan with non-vegan from a same population (not just studying one group), and with mortality rather than biomarker if possible.
Relative Weight, Weight Loss Efforts and Nutrient Intakes among Health-Conscious Vegetarian, Past Vegetarian and Nonvegetarian Women Ages 18 to 50
Methods: Demographic data, lifestyle practices and weight loss efforts (by questionnaire), body mass index (BMI;kg/m2) and dietary intake (via multiple-pass 24-hour diet recall) were compared in a convenience sample of 90 current vegetarians, 35 past vegetarians and 68 nonvegetarians.
Results: Age (31.9 ± 8.8), educational attainment, smoking status, alcohol use, physical activity and perceived health status were similar among the three groups of women. BMI did not differ by dietary pattern and averaged 23.7 ± 4.7 for all women combined. Participants had intentionally lost >= 10 pounds a mean of 2.1 times, and 39% of women perceived themselves to be overweight; again, no differences were observed among dietary groups. Dietary intakes of vegetarians and current nonvegetarians were consistent with current recommendations for macronutrient composition (<30% fat, <10% saturates). Compared to current nonvegetarians, current vegetarians had lower intakes of protein, saturated fat, cholesterol, niacin, vitamins B12 and D, and higher fiber and magnesium intakes. Vegetarians’ mean vitamin B12 and D intakes were well below recommendations.
Conclusions: Relative weight and weight loss efforts do not differ by dietary pattern among similarly health-conscious vegetarian and nonvegetarian women. The only differences in nutrient intake with potential health implications were vitamins D and B12.
(ok this is not about mortality but many vegan brings in the weight control issu so I thought this was worthful of consideration)
How does the health and well-being of young Australian vegetarian and semi-vegetarian women compare with non-vegetarians?
Design: In cross-sectional data analyses of the Australian Longitudinal Study on Women's Health in 2000, 9113 women (aged 22–27 years) were defined as non-vegetarians if they reported including red meat in their diet, as semi-vegetarians if they excluded red meat and as vegetarians if they excluded meat, poultry and fish from their diet.
Results: The estimated prevalence was 3% and 10% for vegetarian and semi-vegetarian young women. Compared with non-vegetarians, vegetarians and semi-vegetarians were more likely to live in urban areas and to not be married. Vegetarians and semi-vegetarians had lower body mass index (mean (95% confidence interval): 22.2 (21.7–22.7) and 23.0 (22.7–23.3) kg m− 2) than non-vegetarians (23.7 (23.6–23.8) kg m− 2) and tended to exercise more. Semi-vegetarians and vegetarians had poorer mental health, with 21–22% reporting depression compared with 15% of non-vegetarians (P < 0.001). Low iron levels and menstrual symptoms were also more common in both vegetarian groups. Vegetarian and semi-vegetarian women were more likely to consult alternative health practitioners and semi-vegetarians reported taking more prescription and non-prescription medications. Compared with non-vegetarians, semi-vegetarians were less likely and vegetarians much less likely to be taking the oral contraceptive pill.
Conclusion: The levels of physical activity and body mass indices of the vegetarian and semi-vegetarian women suggest they are healthier than non-vegetarians. However, the greater reports of menstrual problems and the poorer mental health of these young women may be of clinical significance.
This is exactly what Skotgonung was proposing.
Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies.
Mortality in British vegetarians: results from the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford).
OBJECTIVE: We present results on mortality among vegetarians and nonvegetarians in the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford).
DESIGN: We used a prospective study of men and women recruited throughout the United Kingdom in the 1990s. RESULTS: Among 64,234 participants aged 20-89 y for whom diet group was known, 2965 had died before age 90 by 30 June 2007. The death rates of participants are much lower than average for the United Kingdom. The standardized mortality ratio for all causes of death was 52% (95% CI: 50%, 54%) and was identical in vegetarians and in nonvegetarians. Comparing vegetarians with meat eaters among the 47,254 participants who had no prevalent cardiovascular disease or malignant cancer at recruitment, the death rate ratios adjusted for age, sex, smoking, and alcohol consumption were 0.81 (95% CI: 0.57, 1.16) for ischemic heart disease and 1.03 (95% CI: 0.90, 1.16) for all causes of death.
CONCLUSIONS: The mortality of both the vegetarians and the nonvegetarians in this study is low compared with national rates. Within the study, mortality from circulatory diseases and all causes is not significantly different between vegetarians and meat eaters, but the study is not large enough to exclude small or moderate differences for specific causes of death, and more research on this topic is required.
As I said in the other post, it is not possible to know how would a vegan diet corrected for deficiency compared to a plant-based diet with high quality animal product would compare... but right now it does not look like a vegan diet yield superior result to a regular omnivor diet.
Edited by oehaut, 05 April 2010 - 11:23 PM.