K2 deficiency might be written all over your face
Specifically, the severity of a postmenopausal woman's facial wrinkles predicts her risk of osteoporosis. Women with extensive facial wrinkles are much more likely than their peers to suffer from low bone mass, while those with firmer skin tend to have denser bones, regardless of age or body weight.1
In a similar example, Korean research published in the journal Nephrology in 2008 found that increased facial wrinkling is associated with a reduced kidney filtration rate (a measure of kidney function), independent of age and sex.2 American research published the following year demonstrated that decreased kidney filtration predicts an increase in inactive MGP—in other words, vitamin K2 deficiency.3 When it comes to skin, it seems that a K2 deficiency might be written all over your face.
Pal L, Kidwai N, Glockenberg K, et al. Skin wrinkling and rigidity are predictive of bone mineral density in early postmenopausal women. Endocr Rev 2011, 32(03_Meeting Abstracts): 3–126.)
Park BH, Lee S, Park JW, et al. Facial wrinkles as a predictor of decreased renal function. Nephrology 2008, 13(6): 522–27.
Parker BD, et al. Association of kidney function and uncarboxylated matrix gla protein: data from the Heart and Soul Study. Nephrol Dial Transplant 2009, 24(7): 2095–101, doi:10.1093/ndt/gfp024.)