Is ingredient titanium dioxide in food supplement harmful to health?

Yes and no depending on whether it is inhaled or ingested. Titanium dioxide is a cancer causing agent as listed by the CDC bu only when inhaled. The World Health Organization in their review of titanium dioxide concluded that titanium dioxide is not carcinogenic when ingested. This is similar to coal dust, flour dust etc where inhalation interferes with the uptake of oxygen into the blood stream.

Titanium dioxide is completely inert when ingested and is not harmful to health.

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Other experts disagree with the above opinion, however. For example, Dr. Michael Greger at Nutritionfacts.org says that titanium dioxide (artificial color) should be avoided because it might increase inflammation due to bacterial endotoxins:

http://nutritionfacts.org/video/titanium-dioxide-inflammatory-bowel-disease/

http://nutritionfacts.org/video/the-exogenous-endotoxin-theory/

Vitacost and a few other vitamin supplement sellers have banned all products that contain titanium dioxide from their inventories of products.