Dear Mark: Collagen or Glycine, Keto and Gallstones, Raw Liver, Stevia Itching, and Gaining Muscle, Losing Fat
For today’s edition of Dear Mark, I’m answering five questions taken from this Twitter thread . First, does collagen offer anything special above and beyond glycine? Second, what’s the relationship between keto and gallstones? Third, do I recommend eating raw liver, and why or why not? Fourth, why does one reader’s scalp itch when eating stevia? And finally, what’s the best way to lose fat and gain muscle at the same time? Let’s go: If collagen is broken down into amino acids in the gut before being absorbed, is it just the amino acid profile (i.e. high glycine) that makes it so beneficial? Anything else? Glycine is a major reason why we need collagen in our diets, but it’s not the only one. When you feed people collagen derived from pork skin, chicken feet, and cartilage, many different collagenous peptides appear in the blood . You don’t get any of these from isolated glycine: Proline-hydroxyproline, a peptide with protective effects on osteoarthritic cartilage degradation .