Fat, ground, burnt, and adulterated with steroids, antibiotics, nitrates, sulfites, and chemical preservatives – that’s how the average Westerner “likes” his meat (’cause it’s cheap, you know).
No wonder that the majority of epidemiological studies (you know that’s the branch of science, where people invent explanations for observations) “shows”: red meat kills!
As a SuppVersity reader, you know from previous articles that experimental evidence suggests otherwise… at least for lean, properly prepared meats from appropriately reared animals (those are the animals that don’t make taking extra steroids and antibiotics obsolete).
With the publication of Lauren E O’Connor’s, Douglas Paddon-Jones’, Amy J Wright’s and Wayne W Campbell’s latest paper the number of studies that support the notion “that lean, unprocessed red meat can be incorporated into healthy eating patterns to improve cardiometabolic disease (CMD) risk factors” (O’Connor 2018)” has increased by +1 and provides a link that even (or, rather, especially) people who trust in epidemiology cannot ignore: the Mediterranean Diet link.
In an investigator-blinded, randomized, crossover, controlled feeding trial, 41 overweight or obese [BMI (kg/m²) 25–37], aged 30–69 y [representing middle-aged adults and adulthood life stage groups of the Dietary Reference Intakes (Trumbo 2002)] were provided with a Mediterranean Pattern diet for two 5-wk interventions separated by 4 wk of self-selected eating.
What did this “Mediterranean Pattern diet” diet look like? The diet contained ∼500 g [typical US intake (Med-Red)] and ∼200 g [commonly recommended intake in heart-healthy eating patterns (Med-Control)] of lean, unprocessed beef or pork per week.
Daily macronutrient intakes were targeted at 40% of total energy as carbohydrate, 22% protein, and 40% fat. Daily fat intakes were targeted at 7% of total energy as saturated fat and 20% monounsaturated fat. Med-Red and Med-Control differed predominantly in the amounts of red meat and poultry provided.
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| Figure 1: Overview of the main characteristics of the dietary intervention in O’Connor 2018 |
What is important enough to repeat is that even though the amount of red meat differed significantly, the Med-Red and Med-Control diets contained identical amounts of fish and legumes, were iso-energetic and adapted so that they would provide and (within statistical margins) identical macronutrient content. The diets also had in common that…
- the desired macronutrient ratio was achieved by adding/removing dairy, eggs, and grain products,
- sodium, potassium, magnesium, and calcium intakes were targeted to be within ±15% between the Med-Red and Med-Control menus,
- each subject’s energy requirement was estimated using sex-specific equations and menus were designed to maintain subjects’ baseline 1 body mass
What? Oh, yes – to mirror the red wine intake of the “true” Mediterranean Diet “the subjects were given the option to consume 150 mL of self-selected dry red wine daily” (O’Connor 2018).
Subjects weighed in and met with study staff weekly to monitor body mass and promote compliance, respectively. Subjects completed daily (and returned weekly) menu check-off lists to track self-reported deviations from the provided Mediterranean Pattern. Dietary intake and compliance were measured from the menu check-off lists of 3 d during the last week of each intervention.
Baseline and postintervention outcomes included fasting blood pressure, serum lipids, lipoproteins, glucose, insulin, and ambulatory blood pressure.
The raw data were adjusted for age, sex, and body mass at each time point, the level of significance was set at P < 0.05 and the results… (I know you’ve been waiting for them) were unambiguous:
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Figure 2: Changes in lipids and lipoproteins after consuming a Med-Red or Med-Control diet for 5 wk. Results are presented as LS means ± SEMs (n = 41). Data were analyzed using a doubly repeated-measures ANOVA adjusted for age, sex, and body mass at each time point. *Nondifferential change over time. †Differential response between Med-Red and Med-Control when intervention × time P value < 0.05. ‡Intervention-specific change over time indicated by intervention × time P < 0.05. Med-Red decreased total-C 3% more than Med-Control,
- LDL cholesterol and ApoB decreased by 8% and 6%, respectively, with Med-Red, but did not change with Med-Control,
- the significant reduction in cholesterol, and LDL were more pronounced in the red meat group (see Figure 2),
- total-C:HDL cholesterol, triglycerides, CRP, glucose, insulin, and HOMA-IR score did not change with Med-Red or Med-Control,
- fasting and ambulatory blood pressure parameters improved with both Mediterranean Patterns, except during sleep, independent of red meat intake amount.
Moreover, there were no differences between postintervention values of Med-Red and Med-Control for any CMD risk factors, and no difference between males and females in Mediterranean Pattern-induced cardiometabolic changes were found, independent of red meat intake amount. However, …
“When considering baseline and intervention drink-equivalents as a covariate, there were still greater reductions in total-C with Med-Red, and reductions in LDL cholesterol with Med-Red but no changes with Med-Control, but the overall time effect and intervention-specific effects on ApoB diminished” (O’Connor 2018).
The most fundamental message of the study at hand does therefore remain: Red meat, if it’s unprocessed and sufficiently (<10g of fat) lean is not unhealthier (rather the opposite) than poultry… no matter what epidemiologists will tell you.
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| Table 1: Unadjusted means, SD, and n, at each time point of Med-Red and Med-Control (O’Connor 2018). |
What? Oh, yeah. I hear them. The vegans are crying “fraud”, because – obviously – the control diet should have included no meat at all. True that. An additional group using a completely meat-free (like lacto-ovo-vegetarian) version of the Med Diet would have been a nice add-on but its omission is not a shortcoming of a study that was specifically designed to test the hypothesis “that the amount of red meat consumed would not influence Mediterranean Pattern-induced improvements in CMD risk factors of adults who are overweight or obese” (O’Connor 2018) – to test this was, after all, exactly what the study accomplished.
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| Mediation analysis suggests: It’s not the amount of Cantonese Roast Pork Belly (recipe) you eat that increases the level of inflammation in your body, but the belly you get if you eat too much of it or non-red/processed meat foods | read #SVClassic |
Bottom line: The study at hand adds to the already existing experimental evidence that the link between red meat and heart disease (and metabolic syndrome, as tested in previous studies) is not a mechanistic one … or, let’s be more precise: It’s not a link that’s mediated by the “red” in the meat, but rather by the fat (probably eventually the total calories), the nitrite-forming nitrate salts and its chemical cousins that are sprinkled on and injected into processed meats.
Speaking of which, it’s the nitrates your bacon has been “cured” with that “uncure” (=make you sick)… that’s especially problematic if you put the bacon in a pan and fry it – a process that gives rises to a plethora of well-known carcinogens, but it’s not exclusive to fried bacon 😮
The same sh*t happens upon exposure to stomach acid (Fine 1977) and whenever protein and nitrates are exposed to a highly reactive environment. Now, the industry is smart, no? Well, at least they believe so and add other additives to… yes, you guessed it: to counter the ill effects (=nitrosamine formation) of the previously added additives – well, unless you live in the Mediterranean and cherish Prosciutto di Parma which has been nitrate free (again) for >25 years, already… but I am getting off topic – nitrates and cancer are not heart disease and when it comes to the latter you better don’t buy any meat product that was processed with anything but a knife.
What? Oh, no grinding your bee is perfectly ok, if it’s kept cool during the process and grounding is actually the only process it undergoes … needless to say that the latter this is no longer the case since the lobbyists from Kraft Foods and others have “convinced” the FSIS to (re-)allow sodium benzoate, sodium propionate, and benzoic acid as anti-bacterial agents | Comment!
References:
- Fine, David H., et al. “Formation in vivo of volatile N-nitrosamines in man after ingestion of cooked bacon and spinach.” Nature 265.5596 (1977): 753.
- Glória, M. Beatriz A., James F. Barbour, and Richard A. Scanlan. “Volatile nitrosamines in fried bacon.” Journal of Agricultural and Food Chemistry 45.5 (1997): 1816-1818.
- Micha, Renata, Georgios Michas, and Dariush Mozaffarian. “Unprocessed red and processed meats and risk of coronary artery disease and type 2 diabetes–an updated review of the evidence.” Current atherosclerosis reports 14.6 (2012): 515-524.
- O’Connor, Lauren E., et al. “A Mediterranean-style eating pattern with lean, unprocessed red meat has cardiometabolic benefits for adults who are overweight or obese in a randomized, crossover, controlled feeding trial.” The American Journal of Clinical Nutrition.
- Trumbo, Paula, et al. “Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids.” Journal of the American Dietetic Association 102.11 (2002): 1621-1630.