I am lactose intolerant. Is whey protein bad for me? Is whey protein bad for people with lactose intolerance?

– Dan


“Whey protein” is a catch-all term referring to several proteins found in the whey of milk after solid caseins and moisture are removed. Whey protein is generally okay for those with mild lactose intolerance. Depending on the form, whey protein contains less than 5 gram of lactose per 100 grams dry product, which provides 80-90 of grams protein.* Compare this to the 12 grams of lactose per 245 grams (a cup) of fluid cow’s milk for 8 grams of protein or 1 gram of lactose per 30 grams (an ounce) of some cheeses for 7 grams of protein.

Whey protein as an ingredient or by itself as a supplement is usually found in concentrate or isolate form. Here’s the difference: the highest whey protein concentrate still includes some fat, cholesterol and lactose particles (up to 20%), whereas whey protein isolate has usually undergone microfiltration leaving only 10% as those particles.

Pure whey protein isolate may be tolerated by those with lactose intolerance, but individual response varies. Some whey protein isolates are further processed to be lactose-free. Keep in mind that if the final whey protein supplement product is a shake powder or bar, it has other ingredients that may contribute lactose.

For those with a very severe lactose intolerance much like an allergy, it is best to avoid all milk-derived products.

* From U.S. Dairy Export Council’s Reference Manual for U.S. Whey and Lactose Products. Composition of whey protein concentrate with 80% protein is typically 4%-8% lactose by weight. Composition of whey protein isolate with at least 90% protein is typically 0.5%-1% lactose by weight.

– Debbie J., MS, RD

This article should not replace any exercise program or restrictions, any dietary supplements or restrictions, or any other medical recommendations from your primary care physician. Before starting any exercise program or diet, make sure it is approved by your doctor.

Some questions have been edited for length and/or clarity.

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