According to new research published in the journal Clinical Nutrition, low levels of vitamin D and vitamin K1 are both independently and synergistically associated with hip fracture.
Vitamin D deficiency has long been associated with increased risk of hip fracture. Maintaining good levels of vitamin D helps improve balance and decreases the risk of falling and getting fractures from falls. Vitamin D may also help bone mass density, by slowing the process of losing bone mass as we age, which would also have an effect on the risk of hip fracture.
Vitamin K describes two vitamins, both vitamin K1 (found in leafy greens) and vitamin K2 (found in nattō and in small quantities in hard cheeses and meats). Research in vitamin K is very young, and so far studies have been mixed at how effective it is in decreasing risk of fracture. In a large 4,000-person trial, vitamin K2 supplementation reduced vertebral fractures in patients with severe osteoporosis but showed no effect on hip fractures.
Still, mechanistic studies suggest vitamin K is important for bone density and that it might work with vitamin D synergistically. Bone density depends on the amount of calcium retained in the bone, among other things. A protein called osteocalcin binds calcium to bone. Vitamin D upregulates the production of an inactive form of osteocalcin. Vitamin K then acts as a catalyst to take this inactive type of osteocalcin and make an active form of osteocalcin. Thus vitamin D and vitamin K work together to keep calcium retained in bones.
In the present study, researchers from Oslo University Hospital in Norway examined patients that suffered hip fracture and matched them with controls. They enrolled 116 patients with hip fracture who were admitted to their hospital. They pulled 73 controls from a national census survey who had never had a hip fracture. The researchers took blood samples of all participants.
The researchers wanted to know, do blood levels of vitamin D and vitamin K1 correlate at all with risk of hip fracture? Here’s what they found:
- The hip fracture patients had significantly lower vitamin D levels, with a mean level of 20 ng/ml, compared to the controls (mean level 32.4 ng/ml).
- The hip fracture patients had significantly lower vitamin K1 levels, with a mean level of 0.24 ng/ml, compared to the controls (mean level 0.55 ng/ml).
- If you had a vitamin D level less than the mean and a vitamin K1 level less than the mean, you had a greater than 7 times higher associated risk of hip fracture compared to having a vitamin K1 level above the mean [OR=7.61 (2.26-26.67)]. This relationship wasn’t as strong if you had a vitamin D level above the mean, but still had a vitamin K1 level less than the mean [OR=2.28 (0.39-13.26)].
- Total osteocalcin was highest in those with both high vitamin K1 and vitamin D levels.
The researchers concluded,
“Low serum levels of vitamin K1 and 25(OH)D are independently associated with an increased risk of hip fracture. There is a significant synergistic effect between the two nutrients, possibly mediated through osteocalcin. Vitamin K1 and 25(OH)D may be important in preventing development of osteoporosis and in treatment of hip fracture patients to reduce the risk of subsequent fracture.”
Limitations of this study include its observational design, so it’s not intended to see if there’s a causal relationship between vitamins K1 and D and hip fracture. However, this research shows a clear relationship that hip fracture patients have both low vitamin D and vitamin K1 levels. It’s not fully understood if fracture trauma depletes the body of these nutrients, so the researchers did their best to mitigate this problem, by drawing blood samples as soon as possible upon hospital admission.
Future trials should look to see if vitamin D and vitamin K supplementation can work together to reduce risk of fracture and increase bone mass density.