Glycine is a nutritionally essential amino acid for maximal growth of milk-fed young pigs.

[paymanz]

http://www.ncbi.nlm.nih.gov/pubmed/24858859

Analysis of amino acids in milk protein reveals a relatively low content of glycine. This study was conducted with young pigs to test the hypothesis that milk-fed neonates require dietary glycine supplementation for maximal growth. Fourteen-day-old piglets were allotted randomly into one of four treatments (15 piglets/treatment), representing supplementation with 0, 0.5, 1 or 2% glycine (dry matter basis) to a liquid milk replacer. Food was provided to piglets every 8 h (3 times/day) for 2 weeks. Milk intake (32.0-32.5 g dry matter/kg body weight per day) did not differ between control and glycine-supplemented piglets. Compared with control piglets, dietary supplementation with 0.5, 1 and 2% glycine increased (P < 0.05) plasma concentrations of glycine and serine, daily weight gain, and body weight without affecting body composition, while reducing plasma concentrations of ammonia, urea, and glutamine, in a dose-dependent manner. Dietary supplementation with 0.5, 1 and 2% glycine enhanced (P < 0.05) small-intestinal villus height, glycine transport (measured using Ussing chambers), mRNA levels for GLYT1, and anti-oxidative capacity (indicated by increased concentrations of reduced glutathione and a decreased ratio of oxidized glutathione to reduced glutathione). These novel results indicate, for the first time, that glycine is a nutritionally essential amino acid for maximal protein accretion in milk-fed piglets. The findings not only enhance understanding of protein nutrition, but also have important implications for designing improved formulas to feed human infants, particularly low birth weight and preterm infants.

 

[Such_Saturation]

milk-fed young pigs.

Reporting in

 

[jyb]

I wonder why glycine is so low in milk. Most kids seem to grow up fine with normal skin whatever the health. By normal skin I mean, skin grows a lot as body volume increase and collagen repair is efficient. Maybe initially glycine synthesis is more efficient. What about adults who live on milk?

 

[haidut]

I wonder why glycine is so low in milk. Most kids seem to grow up fine with normal skin whatever the health. By normal skin I mean, skin grows a lot as body volume increase and collagen repair is efficient. Maybe initially glycine synthesis is more efficient. What about adults who live on milk?

I think for younger organisms tryptophan is more important then glycine. Tryptophan is key to growth, which is fine at a young age but not so much when you are older and keeping excessive growth/stimulation is the goal. On a similar note, egg protein, especially the egg whites, have less tryptophan per dry protein weight and massive amounts of glycine (similar to gelatin). I never understood why Peat said egg whites are high in tryptophan and should be avoided. Egg whites actually have less tryptophan per dry protein weight than meats, fish, or even milk. Besides, they have glycine, which Peat said offsets the damage done by tryptophan. I know whole eggs are preferable, but if somebody wants access to cheap, organic protein with tons of glycine then most stores carry liquid pasteurized egg whites that can give you 100g of protein for about $6. Hard to beat both on price and nutritional value.

 

[sm1693]

Cronometer and Nutritiondata list quite small amounts of glycine in egg whites.

 

[BobbyDukes]

Cronometer and Nutritiondata list quite small amounts of glycine in egg whites.

1.7g seems like a fair amount per egg?

There's also a fair amount in cottage cheese? Cheese, in general, seems to have more glycine than milk. Something must increase the glycine content, as part of the manufacturing process?

 

[paymanz]

Cronometer and Nutritiondata list quite small amounts of glycine in egg whites.

1.7g seems like a fair amount per egg?

There's also a fair amount in cottage cheese? Cheese, in general, seems to have more glycine than milk. Something must increase the glycine content, as part of the manufacturing process?

that amount of glycine is based on 200 calorie serving.protein has little calorie so 200 calorie from egg white means a lot of eggs.so it is 1.7g glycine from about 50g total protein.even meat has more glycine than eggs.

 

[BobbyDukes]

This is the protein content for 12 egg whites (200 calories). Pic attached.

I guess if you know what bits to go for (eat) with the meat, it probably would be richer in glycine than the eggs. Still, given that protein content for 12 eggs, 1.7g of glycine would wedge nicely in there to buffer that tryptophan, somewhat.

 

[jyb]

12 eggs for 1.7g is disappointing if we believe in the study that we need a dozen or half a dozen daily, of which a few grams are synthesised endogenously. Seems like only some beef cuts may get us there, other than supplementing...

 

[BobbyDukes]

12 eggs for 1.7g is disappointing if we believe in the study that we need a dozen or half a dozen daily, of which a few grams are synthesised endogenously. Seems like only some beef cuts may get us there, other than supplementing...

Well, one doesn't have to eat 12 egg whites. That was just the figure for 200 calories. I was looking more at the trypto-glycine ratio. So, even for one egg white, there is some glycine in there to offset the tryptophan. Meat is likely superior for glycine, yes.

I think Haidut's original point was about the tryptophan content of egg whites not being all that scary because of them containing glycine, which, they do seem to.

I'm not going to be going out and using egg whites as my protein source. I have felt pretty lousy on them in the past (could be allergenic). I was just interested in how much glycine was in them.