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Protein is a popular nutrition topic for almost all athletes, especially those who compete in strength sports. Recent research indicates that red meat, particularly that which has been highly processed, is associated with a higher incidence of various cardiometabolic diseases. Studies using true experimental designs are still needed to confirm these results. In the meantime, limit your intake of all processed meats (red and white) and prepare food using techniques that minimize the formation of dietary AGEs.

Protein – The Strength Athletes Favorite Nutrient

Perplexed over what type of meat you should be eating?¹³

Protein, Protein, Protein… Upon hearing the words “nutrition”, is there another nutrient that jumps into the mind of strength athletes faster than this one? In my experience, the answer to this question is a quick and emphatic “NO.” Regardless of if I’m talking with seasoned vets or beginning strength athletes, most nutrition related discussions eventually circle back to this topic. It can be a simple question such as, “What type of protein you supplementing with right now?” Other times, it’s a, “… man we need to hit up a steakhouse tonight after we get our workout in and clean up.” Usually when this latter comment is made, another guy/gal in the group will say something like, “They better have some chicken breast there… I only eat white meat.” After a few wisecracks about food choices, a discussion ensues that includes comments related to which type of meat is better both from a performance and health perspective – red or white meat. Ultimately, someone will say, “Ask Sean, he tends to “geek” out with the science stuff. He probably knows.” If you find yourself asking this same question, this is what I can tell you…

Our Current Knowledge of Protein

Here is what we currently know regarding different food sources of protein and muscle growth: Animal proteins stimulate protein synthesis and lead to greater gains in muscle size than plant based proteins in strength training athletes¹². Of the 2 types of dairy proteins, casein appears to inhibit protein catabolism whereas whey seems to stimulates protein anabolism¹⁰¹¹. Now that these facts are clearly established lets look at the data surrounding other animal based proteins ….. (crickets chirping)… (more crickets)…

As you can see, the data is relatively non-existent; outside of research conducted with dairy and soy, I have not seen any studies that have directly compared the effects of various proteins on muscle growth. That being said, the World Health Organization (WHO) measures the quality of proteins based off the Protein Digestibility–Corrected Amino Acid score (PDCAAS)³ as this measure takes into account both the digestibility and essential amino acid content of a given protein source⁴. It has been shown that the true PDCAAS of cow’s milk is superior to that of egg or beef³. Although the PDCAAS are accepted by the WHO, there are some problems with it. These include changes in protein quality with processing, and other ingredients in food products that prevent proper protein absorption⁵. Therefore, I can’t say with 100% certainty that one form of dietary animal protein will lead to greater gains in muscular strength and size vs. that of another source (ie- dairy vs. chicken vs. beef, etc).

Now that we’ve established that there is little research supporting the use of one animal based protein vs. that of another, the next question you may find yourself asking is, “Does the type of animal protein one consumes affect the risk of general cardiometabolic health issues?” To help us answer this question, let’s look at what the research has to say on this question…

Animal Based Proteins and Cardiometabolic Diseases

Red Meat vs. Processed Red Meat

Red meat is by far the most popular source of meat, accounting for 58% of the total meat consumption by individuals within the United States¹². In a recent meta-analysis completed by Micha et al. researchers examined the affects of unprocessed red meat vs. processed red meats on the risk of developing coronary heart disease (CHD) or diabetes mellitus (DM)⁶. {For reference, their study included the results of 20 previously conducted studies, involving >1,200,000 individuals hailing from the United States, Europe, Asia and Australia. Additionally, red meat was considered that of beef, lamb, pork or game animal origin). Upon analyzing the data, researchers found that per 100 g/day, unprocessed red meat was not associated with elevated risk of CHD or diabetes. In contrast, a strong association was found between processed red meat consumption and both cardiometabolic diseases. 50 grams/day of processed red meat increased the risk of developing CHD by 42% and DM by 19%.

The research team also looked at key nutritive differences between processed and non-processed foods commonly consumed in the United States that may help explain the differences observed in this study. Per 50 gram serving, relatively small differences were found in protein (+ ~4 g in unprocessed), kcals (+ ~15 kcals in processed), and cholesterol content (+ ~8 mg unprocessed). Additionally, saturated fat content was relatively the same (+ 0.8 g in processed). The primary differences noted between groups was that processed foods contained ~300% more sodium and 50% more nitrates than non-processed food. Thus, the authors hypothesized that these factors may have contributed to the increased risk of CHD and diabetes when consuming processed red meats.

Red vs. White Meat and Beyond

The effect of various protein sources on the development of CHD has also been examined by Bernstein et al⁷. Their prospective study followed >84,000 women for 26 years. At the start of the study, women were between the ages of 30-55 years old and were free of any sort of cardiovascular disease. In contrast to Micha et al.⁶, Berstein and colleagues looked at the effects of red meat (processed and unprocessed), fish, poultry, dairy, nuts and beans on CHD. Final results of their study indicated that higher intakes of total and processed red meat were associated with increased risk of developing CHD. In contrast, low fat dairy, fish, poultry, and nuts were associated with a decreased the risk of developing CHD. More specifically when compared to 1 serving per day of total red meat, these other protein sources reduced the risk of developing the disease by:

• Nuts – 30%

• Fish – 24%

• Poultry – 19%

• Low Fat Dairy – 13%

Bernstein et al. suggested a few possible reasons explaining why red meat may be associated with a higher risk of coronary heart disease⁷. These included higher dietary intake of heme iron (the type of iron in red meat) which have been shown in both men⁸ and middle aged women⁹ to increase heart disease. They also noted the high salt content of processed meats which affects blood pressure as well as the presence of dietary AGEs which I’ve discussed in previous articles (Part I, Part II).

Study Limitations and Applying the Research

The studies completed by Micha et al.⁶ and Bernstein et al. shed interesting light on the impact of various protein sources on the development of various cardiometabolic diseases. However, before we go overboard and condemn red meat, I’d like to point out that these are epidemiological based studies. As discussed in my article, Research 101, epidemiological studies show associations between variables rather than true cause and effect relationships. Experimental studies must be undertaken to confirm the results reported by Micha et al. & Bernstein et al.

All this being said, I have to be honest with you… I absolutely LOVE red meat and have been known to eat a piece of venison jerky (ie – processed red meat) from time to time. The likelihood that I’m going to completely discard these foods from my diet is slim to none. Thus, you may be wondering how I personally apply this research to my dietary eating habits. First, I try to limit my intake of ALL processed meat. This includes both processed WHITE and RED meat. Remember, processed white meat, such as turkey luncheon meat, still includes higher sodium and nitrate levels, than the unprocessed versions. For the processed meat that I do eat, which happens to be mostly venison based products, the meat comes from wild sources (ie-deer) and I know exactly what is all put into the meat during the curing process. With respect to unprocessed red meat, I cook it using techniques that minimize the formation of dietary AGEs, food compounds that are believed to contribute to various cardiometabolic diseases. Again, I’d like to refer you to Part II of my dietary AGE series for ways on how to minimize the formation of these compounds during the cooking process.

Bottom Line

Protein is a popular nutrition topic for almost all athletes, especially those who compete in strength sports. Recent epidemiological studies reveal that high intakes of red meat, especially that which is highly processed, may affect our risk of developing various cardiometabolic diseases. However, before we d*mn all red meat, let’s remember that experimental studies are STILL needed to show a true cause/effect relationship between this source of dietary protein and various cardiometabolic diseases.

In the meantime, limit your intake of BOTH red and white processed meat, obtain your protein from a variety of sources, and prepare your meat using techniques that minimize the formation of dietary AGEs.

References

¹ Wilkinson SB, Tarnopolsky MA, Macdonald MJ, Macdonald JR, Armstrong D, Phillips SM. Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage. Am J Clin Nutr. 2007 Apr;85(4):1031-40.

² Hartman JW, Tang JE, Wilkinson SB, Tarnopolsky MA, Lawrence RL, Fullerton AV, Phillips SM. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. Am J Clin Nutr. 2007 Aug;86(2):373-81.

³ Reeds, P., Schaafsma, G., Tome, D., & Young, V. (2000). Criteria and significance of dietary protein sources in humans. summary of the workshop with recommendations. The Journal of Nutrition, 130(7), 1874S-6S.

⁴ Schaafsma, G. (2000). The protein digestibility-corrected amino acid score. The Journal of Nutrition, 130(7), 1865S-7S.

⁵ Schaafsma G. The Protein Digestibility-Corrected Amino Acid Score (PDCAAS)—a concept for describing protein quality in foods and food ingredients: a critical review. J AOAC Int. 2005 May-Jun;88(3):988-94.

⁶ Micha R, Wallace SK, Mozaffarian D. Red and processed meat consumption and risk of incident coronary heart disease, stroke, and diabetes mellitus: a systematic review and meta-analysis. Circulation. 2010 Jun 1;121(21):2271-83. Epub 2010 May 17.

⁷ Bernstein AM, Sun Q, Hu FB, Stampfer MJ, Manson JE, Willett WC. Major dietary protein sources and risk of coronary heart disease in women. Circulation. 2010 Aug 31;122(9):876-83. Epub 2010 Aug 16.

⁸ Ascherio A, Willett WC, Rimm EB, Giovannucci EL, Stampfer MJ. Dietary iron intake and risk of coronary disease among men. Circulation.1994;89:969–974.

⁹ van der AD, Peeters PH, Grobbee DE, Marx JJ, van der Schouw YT. Dietary haem iron and coronary heart disease in women. Eur Heart J. 2005;26:257–262.

¹⁰ Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrère B. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14930-5.

¹¹ Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol. 2009 Sep;107(3):987-92. Epub 2009 Jul 9.

¹² Daniel CR, Cross AJ, Koebnick C, Sinha R. Trends in meat consumption in the USA. Public Health Nutr. 2010 Nov 12:1-9. [Epub ahead of print]

¹³ Image taken by Joe Mabel and is under the GNU Free Documentation License Version 1.2. Image accessed on November 14, 2010 from: http://commons.wikimedia.org/wiki/File:Pike_Place_Market_-_Bavarian_Meats_01.jpg