sweet potatoes and protein digestion??

[Abena]

So I read a super old online book about sweet potatoes and its trypsin inhibitors. then I got curious and got on pubmed for WAY too long trying to find more info. One study showed that in vitro, raw sweet potatoes would inhibit trypsin activity, thus decreasing the digestion of proteins since they couldnt be cleaved. the trypsin inhibitor is heat labile, so cooking the potato would elimnate that problem. it suggested that eating raw sweet potatoes would decrease protein digestion and absorption in vivo....

so now I am super curious!!

other protease inhibitors exist in soybeans, lima beans, some other crap....that inhibit trypsin and/or chymotrypsin. there seems to be a lot of research about this and soybeans.

anybody bored on a saturday and want to help me find more information? how big is the effect of trypsin/protease inhibitors on protein digestion? does it really only matter in severly malnourished?


just found older post from emma leigh:

studied rats......any human studies??, or more recent publications?


J AOAC Int. 2005 May-Jun;88(3):967-87.Links
Effects of antinutritional factors on protein digestibility and amino acid availability in foods.
Gilani GS, Cockell KA, Sepehr E.
Health Canada, Nutrition Research Division, Bureau of Nutritional Sciences, Banting Research Centre (AL: 2203 C), Tunney's Pasture, Ottawa, ON, K1A 0L2, Canada. sarwar_gilani@hc-sc.gc.ca

Digestibility of protein in traditional diets from developing countries such as India, Guatemala, and Brazil is considerably lower compared to that of protein in typical North American diets (54-78 versus 88-94%). The presence of less digestible protein fractions, high levels of insoluble fiber, and high concentrations of antinutritional factors in the diets of developing countries, which are based on less refined cereals and grain legumes as major sources of protein, are responsible for poor digestibility of protein. The effects of the presence of some of the important antinutritional factors on protein and amino digestibilities of food and feed products are reviewed in this chapter. Food and feed products may contain a number of antinutritional factors that may adversely affect protein digestibility and amino acid availability. Antinutritional factors may occur naturally, such as glucosinolates in mustard and rapeseed protein products, trypsin inhibitors and hemagglutinins in legumes, tannins in legumes and cereals, phytates in cereals and oilseeds, and gossypol in cottonseed protein products. Antinutritional factors may also be formed during heat/alkaline processing of protein products, yielding Maillard compounds, oxidized forms of sulfur amino acids, D-amino acids, and lysinoalanine (LAL, an unnatural amino acid derivative). The presence of high levels of dietary trypsin inhibitors from soybeans, kidney beans, or other grain legumes can cause substantial reductions in protein and amino acid digestibilities (up to 50%) in rats and pigs. Similarly, the presence of high levels of tannins in cereals, such as sorghum, and grain legumes, such as fababean (Vicia faba L.), can result in significantly reduced protein and amino acid digestibilities (up to 23%) in rats, poultry, and pigs. Studies involving phytase supplementation of production rations for swine or poultry have provided indirect evidence that normally encountered levels of phytates in cereals and legumes can reduce protein and amino acid digestibilities by up to 10%. D-amino acids and LAL formed during alkaline/heat treatment of proteins such as casein, lactalbumin, soy protein isolate, or wheat proteins are poorly digestible (less than 40%), and their presence can reduce protein digestibility by up to 28% in rats and pigs. A comparison of the protein digestibility determination in young (5-week) versus old (20-month) rats suggests greater susceptibility to the adverse effects of antinutritional factors in old rats than in young rats. Therefore, the inclusion of protein digestibility data obtained with young rats, as the recommended animal model, in the calculation of PDCAAS (Protein Digestibility-Corrected Amino Acid Score) may overestimate protein digestibility and quality of products, especially those containing antinutritional factors, for the elderly. For products specifically intended for the elderly, protein digestibility should be determined using more mature rats.

[infernooo]

Are you just curious or genuinly worried? From the controlled studies I have read, this doesn't appear to be a problem unless you are consuming vast quantities of raw beans or certain starches (e.g. sweet potato, kidney beans etc as mentioned).

[clr18287]

i will say, since switching to the anabolic diet coming from tom venutos BFFM (40-40-20).. my protein digestion, stomach acidity, and overall digestive wellbeing has increased tenfold. no gas, no bloating.. for a long time i suffered from a lack of stomach acid and had to supplement with betaine hcl and digestie enzymes. Now, all that fat and meat sans starches and tons of fiber has ramped up intestinal fortitude for sure.

[gonna_be_big]

Originally Posted by clr18287

i will say, since switching to the anabolic diet coming from tom venutos BFFM (40-40-20).. my protein digestion, stomach acidity, and overall digestive wellbeing has increased tenfold. no gas, no bloating.. for a long time i suffered from a lack of stomach acid and had to supplement with betaine hcl and digestie enzymes. Now, all that fat and meat sans starches and tons of fiber has ramped up intestinal fortitude for sure.

maybe your diet was just crap before?

[clr18287]

Originally Posted by gonna_be_big

maybe your diet was just crap before?

nah dont think so, foods included grass fed beef from a local ranch, local chickens, organic fruits and veg from my farm share. never cheated. the combination of foods just didn't sit well for me.

[Nick Helm]

I've never met anyone that eats raw sweet potatoes, so you should be safe. Also, trypsin isn't the only enzyme that breaks down proteins in the stomach. Did your research reveal whether the sweet potatoes blocked trypsin from the protein, or if they prevented trypsinogen from becoming trypsin? This happens only in an acidic environment, so if the pH of your stomach isn't low enough, it could hinder protein digestion, however, after the protein leaves your stomach, it enters your small intestine, which is an alkaline environment. This is where the final digestion, and then absorption take place.

As for the comment from a different post about gas... Gas comes largely from the fermentation of soluble fiber in the large intestine. The products of the fermentation are gas and short-chain fatty acids. Too much soluble fiber is a sure fire way to be gassy.