This study aimed to investigate the association between dietary Vitamin K1 intake and fracture-associated hospitalizations among older Australian women living in the community (n = 1373, ≥70 years old).

It is well known that vitamin K plays a vital role in blood clotting. Still, recent research has focused on how vitamin K may affect diseases like heart disease, osteoporosis, diabetes, and cancer. This is because vitamin K stimulates bone growth and mineralization (the process that strengthens bones) by activating proteins.

Two forms of vitamin K are available – vitamin K1 and vitamin K2, with vitamin K1 primarily found in green, leafy, cruciferous vegetables. Vitamin K2, produced mainly by bacteria, is further divided into subgroups named MK4 to MK13, found in dairy products, pork, poultry, and fermented foods.

Vitamin K (VK) is a lipid-soluble vitamin essential for blood coagulation and skeletal health; PK comes from spinach and green vegetables, such as kale. Natto (fermented soybeans), dairy items, egg yolk, liver, and meat are all fermented foods that contain MKs, which are synthesized by normal intestinal flora.

Different types of vitamin K contribute to bone health. It is one of the co-enzymes of the gamma-glutamyl carboxylase enzyme, which converts glutamic acid (Glu) residues in VK-dependent proteins into gamma-carboxyglutamic acid (GIa).

Vitamin K regulates osteoblastic markers’ transcription, osteoclasts’ formation, and bone resorption. Many VKDPs can be found in the bones, including osteocalcin (OC), matrix Gla protein (MGP), gas 6, and protein S. 

Studies have shown that low serum vitamin K1 correlates with high levels of undercarboxylated osteocalcin (ucOC). Low vitamin K1 and vitamin K2 intake may increase fracture risk.

What Did the Study Reveal?

The researchers used a validated food frequency questionnaire, a new Australian Vitamin K nutrient database, and published data to estimate dietary Vitamin K1 intake at baseline (1998).

We used linked health data to capture all fracture (n = 404) and hip fracture (n = 153) hospitalizations over 14.5 years. In addition to plasma vitamin D status, serum undercarboxylated osteocalcin (ucOC) and total osteocalcin (tOC) were assessed at baseline.

An inverse association between ucOC and tOC, a measure of vitamin K status, supported estimates of dietary Vitamin K1 intake. According to a multivariable-adjusted analysis, women with the highest vitamin K1 intake were less likely to experience fracture and hip fracture-related hospitalizations than women with the lowest vitamin K1 intake.

Using a spline analysis, researchers found the relative hazard for fracture-related hospitalizations to be lowest at a Vitamin K1 intake of approximately 100 g per day. For hip fractures, the relative risk was similar.

In community-living older women, higher intakes of Vitamin K1 are associated with a reduced risk of fracture- and hip fracture-related hospitalizations.

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