True, overgrowth of GI flora can cause vitamin K deficiency by disrupting the normal synthesis and absorption of the vitamin in the intestine. While often synthesized by beneficial bacteria, an imbalance in the gut microbiome can lead to lowered vitamin K levels.
It is true that one cause of vitamin K deficiency is the overgrowth of GI flora, which can interfere with the normal production and absorption of vitamin K. In a healthy individual, the bacteria present in the intestine synthesize adequate amounts of vitamin K, making deficiency rare except in certain situations like in newborns fed on mother's milk from a diet low in vitamin K. However, when there's an overgrowth of non-beneficial bacteria, it can lead to a deficiency.
Vitamin K is critical for blood clotting and bone health, and while the body does store small amounts of this vitamin, intestinal synthesis by bacteria significantly contributes to meeting the body's needs. This synthesis can be disrupted by an overgrowth of harmful bacteria, leading to a deficiency. Also, vitamin K absorption depends on the integrity of the GI tract's lining, and villi damage can impede this process. In extreme cases, prolonged negative nitrogen balance, gastrointestinal losses, and metabolic alkalosis can be associated with K deficiency.