Originally published in our Summer 2013 newsletter
Powdered protein supplements, designed for mixing with liquids for quick and easy nutrition, have become very popular in our fast-paced world. But are they a smart idea or simply expensive waste material? Research is suggesting that these drinks are often not well assimilated, because of their fast transit through the small intestine where protein is absorbed.
What does the research say?
Estimates for transit times following ingestion of a meal of solid, mixed foods based on numerous studies suggest that 50% of the contents of the small intestines are emptied after 2.5 to 3 hours, with complete contents presumably taking much longer. A study observing the transit of a liquid whey protein supplement showed that it spent only 1.5 hours in the small intestine. Adding fat (such as fish oil or other oil) to the liquid supplement speeds it up even more. The maximum rate that the small intestine can absorb whey protein (one of the better absorbed proteins) is about 8-10 grams per hour. If this research is accurate, then only 12-15 grams of protein can be absorbed from a protein drink. Many of these products contain 30 to 50 grams of protein per serving. That means that 15 to 35 grams of protein are being wasted since it cannot be absorbed once it moves out of that part of the digestive tract. A standard solid meal taking 4 or more hours to transit the small intestine permits absorption of 48 to 60 grams of protein. This is quite adequate for a typical meal containing about 40 grams of protein.
How to best absorb protein?
So it appears that eating solid food is the best way to consume protein. If you are using protein shakes, then check that your serving size does not exceed 15 grams of protein. Consuming it with solid food such as fruit can help to slow it down. Taking protein-specific digestive enzymes may help to absorb higher amounts of protein, but be sure these are plant-sourced enzymes. Digestive enzymes from animal sources inhibit the production of your own enzymes. And always check with your healthcare practitioner to see if using digestive enzymes is safe for you. There are some important contra-indications for the use of enzymes.