Dr. Ron’s Research Review – April 11, 2012

This week’s research review focuses on red meat.

A large-scale prospective longitudinal study showed that consumption of both processed and unprocessed red meat is associated with an increased risk of premature mortality from all causes as well as from cardiovascular disease and cancer. The article presented results from two prospective cohort studies with more than 37,000 men from the Harvard Health Professionals Follow-Up Study and more than 83,000 women from the Harvard Nurses Health Study who were followed up for almost 3 million person-years. (Pan, Sun et al. 2012)

In a related study, red meat consumption was also associated with an increased risk of type 2 diabetes mellitus.  This included the two cohort studies above, plus more than 87,000 women in the Nurses' Health Study II.  (Pan, Sun et al. 2011) (Steinbrecher, Erber et al. 2011)

Substitution of red meat with fish, poultry, nuts, legumes, low-fat dairy products, and whole grains was associated with a significantly lower risk of mortality.

Dean Ornish, MD weighs in with "Holy Cow! What's Good For You Is Good For Our Planet." Many people are surprised to learn that animal agri-business generates more greenhouse gases than all forms of transportation combined. The livestock sec- tor generates more greenhouse gas emissions than transportation as measured in carbon dioxide equivalent (18% vs 13%). It is also responsible for 37% of all the human-induced methane, which is 23 times more toxic to the ozone layer than carbon dioxide, as well as generating 65% of the human-related nitrous oxide, which has 296 times the global warming potential of carbon dioxide. (Ornish 2012)

Dr. Ron


Articles

Holy Cow! What's Good For You Is Good For Our Planet: Comment on "Red Meat Consumption and Mortality"

            (Ornish 2012) Download

Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis

            (Pan, Sun et al. 2011) Download

BACKGROUND: The relation between consumption of different types of red meats and risk of type 2 diabetes (T2D) remains uncertain. OBJECTIVE: We evaluated the association between unprocessed and processed red meat consumption and incident T2D in US adults. DESIGN: We followed 37,083 men in the Health Professionals Follow-Up Study (1986-2006), 79,570 women in the Nurses' Health Study I (1980-2008), and 87,504 women in the Nurses' Health Study II (1991-2005). Diet was assessed by validated food-frequency questionnaires, and data were updated every 4 y. Incident T2D was confirmed by a validated supplementary questionnaire. RESULTS: During 4,033,322 person-years of follow-up, we documented 13,759 incident T2D cases. After adjustment for age, BMI, and other lifestyle and dietary risk factors, both unprocessed and processed red meat intakes were positively associated with T2D risk in each cohort (all P-trend <0.001). The pooled HRs (95% CIs) for a one serving/d increase in unprocessed, processed, and total red meat consumption were 1.12 (1.08, 1.16), 1.32 (1.25, 1.40), and 1.14 (1.10, 1.18), respectively. The results were confirmed by a meta-analysis (442,101 participants and 28,228 diabetes cases): the RRs (95% CIs) were 1.19 (1.04, 1.37) and 1.51 (1.25, 1.83) for 100 g unprocessed red meat/d and for 50 g processed red meat/d, respectively. We estimated that substitutions of one serving of nuts, low-fat dairy, and whole grains per day for one serving of red meat per day were associated with a 16-35% lower risk of T2D. CONCLUSION: Our results suggest that red meat consumption, particularly processed red meat, is associated with an increased risk of T2D.

Red Meat Consumption and Mortality: Results From 2 Prospective Cohort Studies

            (Pan, Sun et al. 2012) Download

BACKGROUND: Red meat consumption has been associated with an increased risk of chronic diseases. However, its relationship with mortality remains uncertain. METHODS: We prospectively observed 37 698 men from the Health Professionals Follow-up Study (1986-2008) and 83 644 women from the Nurses' Health Study (1980-2008) who were free of cardiovascular disease (CVD) and cancer at baseline. Diet was assessed by validated food frequency questionnaires and updated every 4 years. RESULTS: We documented 23 926 deaths (including 5910 CVD and 9464 cancer deaths) during 2.96 million person-years of follow-up. After multivariate adjustment for major lifestyle and dietary risk factors, the pooled hazard ratio (HR) (95% CI) of total mortality for a 1-serving-per-day increase was 1.13 (1.07-1.20) for unprocessed red meat and 1.20 (1.15-1.24) for processed red meat. The corresponding HRs (95% CIs) were 1.18 (1.13-1.23) and 1.21 (1.13-1.31) for CVD mortality and 1.10 (1.06-1.14) and 1.16 (1.09-1.23) for cancer mortality. We estimated that substitutions of 1 serving per day of other foods (including fish, poultry, nuts, legumes, low-fat dairy, and whole grains) for 1 serving per day of red meat were associated with a 7% to 19% lower mortality risk. We also estimated that 9.3% of deaths in men and 7.6% in women in these cohorts could be prevented at the end of follow-up if all the individuals consumed fewer than 0.5 servings per day (approximately 42 g/d) of red meat. CONCLUSIONS: Red meat consumption is associated with an increased risk of total, CVD, and cancer mortality. Substitution of other healthy protein sources for red meat is associated with a lower mortality risk.

Meat consumption and risk of type 2 diabetes: the Multiethnic Cohort

            (Steinbrecher, Erber et al. 2011) Download

OBJECTIVE: To examine the association of meat consumption with diabetes risk in the Hawaii component of the Multiethnic Cohort and to assess effect modification by ethnicity. DESIGN: A prospective cohort study. Baseline information on diet and lifestyle was assessed by questionnaire. The cohort was followed up for incident cases of diabetes, which were identified through self-reports, medication questionnaires, or health plan linkages. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals for diabetes associated with quintile of meat consumption. SETTING: Hawaii, USA. SUBJECTS: A total of 29,759 Caucasian, 35,244 Japanese-American and 10,509 Native Hawaiian men and women, aged 45-75 years at baseline. RESULTS: During a mean follow-up time of 14 years, 8587 incident diabetes cases were identified. Intake of red meat was positively associated with diabetes risk in men (fifth v. first quintile: HR=1.43; 95% CI 1.29, 1.59) and women (fifth v. first quintile: HR=1.30; 95% CI 1.17, 1.45) in adjusted models. The respective HR for processed red meat intake were 1.57 (95% CI 1.42, 1.75) and 1.45 (95% CI 1.30, 1.62). The association for processed poultry was weaker than for processed red meat, and fresh poultry intake was not associated with diabetes risk. For men only, we observed significant interactions of ethnicity with the red and processed red meat associations, with Caucasians experiencing slightly higher risks than Japanese-Americans. CONCLUSIONS: Our findings support the growing evidence that red and processed meat intake increase risk for diabetes irrespective of ethnicity and level of BMI.


References

Ornish, D. (2012). "Holy Cow! What's Good For You Is Good For Our Planet: Comment on "Red Meat Consumption and Mortality"." Arch Intern Med.

Pan, A., Q. Sun, et al. (2012). "Red Meat Consumption and Mortality: Results From 2 Prospective Cohort Studies." Arch Intern Med.

Pan, A., Q. Sun, et al. (2011). "Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis." Am J Clin Nutr 94(4): 1088-96.

Steinbrecher, A., E. Erber, et al. (2011). "Meat consumption and risk of type 2 diabetes: the Multiethnic Cohort." Public Health Nutr 14(4): 568-74.