Grass-Fed Beef: Does CLA make the difference? Probably Not.

You certainly have heard of the benefits of the meat of grass-fed, i.e. naturally nourished, cows. Well, although I do not want to question its general superiority to corn-fed high omega-6 meat, it probably is not the CLA content which distinguishes good from not so good meat sources.

A recent study, which was conducted by scientists from the Iowa State University (Brown. 2011), scientists investigated the effect of a "balanced nutritionally complete diet" (31% energy from lipid, 13% from protein, and 54% from carbohydrate) with either high (1.17 g/d) or low (0.35 g/d) CLA content on various health parameters of 18 healthy women aged between 20 to 39 years over a 8 weeks period. These are the results:

The CLA diet did not result in any differences in insulin sensitivity, body composition, circulating blood lipids, or other measured disease risk factors as compared with the control diet.

Accordingly, the scientists concluded "that a diet naturally enriched with over a 3-fold increase in CLA from pasture-fed cattle "did not provide a health benefit when compared to "a similar diet composed of foods from grain-fed cattle."

While these results stand in line with the generally equivocal findings on possible health benefits from CLA supplementation in human beings, it remains questionable whether with a "nutritionally less complete [from a government standpoint]" diet, i.e. a diet with less carbohydrate content and a consequently higher meat consumption, the results would not have been totally different.

Figure 1: Fatty acid composition of grass-fed vs. conventional meats.

All that aside, a study by Irish scientists (McAfee. 2011) showed that the CLA content of grass-fed vs. conventional meat is not all that different, anyway. According to McAfee et al. it is rather the n-3 PUFA content of grass fed meat which "can significantly increase consumer plasma and platelet LC n-3 PUFA status" and may thus have a positive influence on metabolic risk factors in general and n-6 to n-3 PUFA ratio in particular.

High Protein Diet Safe for Bones! Acid Load due to Meat Protein does not Compromise Calcium Metabolism.

Reading the caption of this post, some of you may rightly ask themselves: "Why does he even mention this? Of course, meat is safe - meat is natural and eating meat is what man is made for!" So, if you already knew all that, you can stop reading now. If, however, you still belong to the misguided brotherhood of the followers of the holy food pyramid with your "healthy" grains, pasta and cereals at the bottom, you may be interested in the results from an older scientific paper I just came across while posting an answer to a forum post of someone who was concerned that his bones will become brittle if he increases his protein intake beyond the 0.8g/kg body weight barrier.

In November 2010, Cao & Nilsen (Cao. 2010) published a review which analyzed the outcome of studies that investigated the effect of the purported renal acid load resulting from a high protein intake (above the current Recommended Dietary Allowance of 0.8 g protein/kg body weight) on increased urinary calcium excretion. With reference to more recent findings they write:

Neither whole body calcium balance is, nor are bone status indicators, negatively affected by the increased acid load. Contrary to the supposed detrimental effect of protein, the majority of epidemiological studies have shown that long-term high-protein intake increases bone mineral density and reduces bone fracture incidence. The beneficial effects of protein such as increasing intestinal calcium absorption and circulating IGF-I whereas lowering serum parathyroid hormone sufficiently offset any negative effects of the acid load of protein on bone health.

By the way, I am already looking forward to the huge steaks I am going to have for lunch, today ;-)