Magnesium Stearate is Generally Recognized as Safe (GRAS) to consume. Since it is used as an excipient or inert ingredient, there is not enough to cause any problems. However when it is used as a major filler in many other supplements and medications on the market, if you ingest too much, it can have a mild laxative effect.
Some people on the internet claim that Magnesium Stearate suppresses your immune T-cell function and causes the cell membrane integrity in your helper T-cells to collapse. However, there is no scientific evidence to support those claims.
These claims have been made based on a single mouse study that was related to stearic acid, NOT magnesium stearate. Mice lack an enzyme in their T-cells that humans have. This makes stearic acid safe for us to ingest.
Some people have also claimed that Magnesium Stearate might interfere with your body’s ability to absorb the contents of medication or supplements tablets and capsules. But again, there is no scientific evidence to support those claims.
Some people report having negative reactions to Magnesium Stearate and feel much better when they eliminate it. These people might have a sensitivity to it. It is possible to be allergic to Magnesium Stearate like any ingredient (although it would be rare) and it can be difficult to avoid this food additive since it's in many packaged and processed foods whether listed or not.
The Food and Drug Administration (FDA) has approved Magnesium Stearate for use as an additive in food and supplements.
According to the National Center for Biotechnology Information, it is considered safe for consumption in amounts below 2,500 milligrams (mg) per kilogram per day. That means for a 150-pound adult, that equals 170,000 mg per day that can be consumed (about 1/3 of a pound). Since there is less than a trace amount in Curcumin Plus, that can not be measured, (again being an excipient or inert ingredient), it is very safe to consume without concern and does not have enough to cause negative side effects.