Monday, May 8, 2017

Minimally Processed and Eaten as Part of a Mediterranean-Style Diet, Red Meat Augments MED's Heart Health Benefits

The extra reduction in diastolic blood pressure may translate to a significantly reduced stroke risk. Especially in younger people, a few mmHg can make a tenfold difference in their risk of stroke.
If you follow the mainstream media you will get the impression that eating red meat was worse for your heart than drinking or smoking. In fact, however, the experimental evidence from decently controlled human studies like the latest paper by scientists from the Purdue University and the University of Texas Medical Branch, indicate that red meat - if it's still meat and not bought in processed food, i.e. salami, sausages, wurst, etc. is completely harmless, if not beneficial to your heart health.

Beneficial? Yes, you read that right: As Lauren E O’Connor's randomized investigator-blinded crossover study shows, adding 70g of beef/pork to a Mediterranean diet has no effect on the beneficial effects of the MED on selected markers of cardiovascular health, it even augmented the reduction in diastolic blood pressure - a highly relevant difference, in view of the fact that an elevated diastolic blood pressure is associated in  <45, 45-64, and 65+ year-olds with a 10-, 5-, and 2-fold, respectively, increased risk of stroke (Prospective Studies Collaboration 1995)!
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Before we go too much into detail, though, it appears prudent to scrutinize the study design and decide how representative of potential real-world effects of red meat consumption it is.

As previously pointed out, we're dealing with a randomized investigator-blinded crossover study in 25 women and 13 men (aged 46 ± 2 y, BMI 30.6 ± 0.6 kg/m2) who were not already following a healthy eating pattern. The subjects consumed a weight-maintenance MED for two 5-wk periods separated by a 4-wk washout period (note: the scientists verified that the baseline CVD risk factor values did not differ between trials, which supports an effective washout period).
Figure 1: Graphical illustration of the study cross-over study design O'Connor et al. used.
The MED diets were either restricted or rich in minimally processed lean red meat (5.5 oz./154g or 18.2 oz./510g of beef/pork per week, respectively). Both diets contained 20/40/40% of total energy from protein/carbohydrate/fat, respectively, with a fatty acid ratio of 22/11/7% of total energy from monounsaturated/polyunsaturated/saturated fats, respectively.
'High normal' (129-139 / 84-95 mmHg) blood pressure can also kill you - not today or tomorrow, but it entails significant health risks | learn more
Don't ignore your diastolic blood pressure, especially if you're still young! When you read about high blood pressure in the mainstream media, oftentimes, only the effects of increased systolic blood pressure are discussed. Especially for young people, however, it's the diastolic (lower number on your monitor) that makes all the difference. As Li et al. point out, below age 50, it's your 24h diastolic, not systolic blood pressure profile that determines your risk of  nonfatal cardiovascular, cardiac, or coronary events and even mortality with a difference as it was observed in the study at hand being enough to decrease your risk of the former 2.05 times (P=0.0039) and the latter 4.07 times irrespective of your systolic blood pressure!
At baseline and during the last week of each intervention fasting BPs, blood lipids and lipoproteins, and body composition (via a BOD POD®) were measured and subjects wore an ambulatory BP monitor for 24 hours. All data were analyzed by doubly repeated measures ANOVA adjusted for age, body mass, and sex using Tukey-Kramer adjusted p values with a significance level of p<0.05. Data are presented as adjusted least squares means and SEM.
Figure 2: Differential effects on blood pressure (illustrated on the left) and the subjects' lipoproteins (total cholesterol, LDL, and HDL in mg/dL); data expressed as change from baseline (O'Connor 2017)
As previously pointed out, the consumption of a MED diet decreased all BP parameters over time (~3-6 and ~2–5 mm Hg decrease in all systolic and diastolic BPs, respectively) and inclusion of higher amounts of minimally processed lean red meat did not influence results except for a greater reduction in waking diastolic BP with consumption of the Med diet rich in red meat (p=0.043).

Similarly, the decrease in total cholesterol (− 16 ± 4 and  −9 ± 4), LDL (−10 ± 4 and −4 ± 4), and HDL(−4 ± 2 −5 ± 2) were more favorable (albeit not significantly) for the red meat "enhanced" MED diet compared to its restricted counterpart. No differences were seen for triglycerides, the total cholesterol to HDL ratio, and body composition - neither of these values changed over time with either diet.
If you want to learn what you should and what you shouldn't do to your (red) meats and other protein sources in order to retain their health effects, read the "Protein Oxidation 101: 8 Simple Rules to Minimize PROTOX and Maximize the Proven Benefits of High(er) Protein Diets" | more.
Minimally processed is the keyword, here? Next to the fact that you always have to account for the overall dietary pattern (the epidemiological "red meat is bad studies" don't do that), the main, and in my humble opinion, most important message of the study at hand is that minimally processed meat, i.e. meat that's still recognizable as meat, when you buy it (yes, this excludes salami, Frankfurter, Wiener, regular bacon, all forms of wurst etc.) and not breaded and fried at home, is not a (heart) health problem. Whether you'd also see beneficial effects, as in the study at hand, if you ate more than the 510g of beef/port per week that were consumed in the "red meat" trial of the study at hand, however, will have to be investigated in future studies and unhealthier subjects | Comment on Facebook!
  • Li, Yan, et al. "Ambulatory Hypertension Subtypes and 24-Hour Systolic and Diastolic Blood Pressure as Distinct Outcome Predictors in 8341 Untreated People Recruited From 12 PopulationsCLINICAL PERSPECTIVE." Circulation 130.6 (2014): 466-474.
  • O’Connor, Lauren E., et al. "Daily Red Meat Intake does not Affect Improvements in Cardiovascular Disease Risk Factors Induced by Consuming the USDA’s Healthy Mediterranean-Style Eating Pattern." The FASEB Journal 31.1 Supplement (2017): 966-9.
  • Prospective Studies Collaboration. "Cholesterol, diastolic blood pressure, and stroke: 13 000 strokes in 450 000 people in 45 prospective cohorts." The Lancet 346.8991 (1995): 1647-1653.