Vitamin K benefits the bones
In 2014 I attended a presentation by Dr. Susan Lanham-New, a researcher and professor at Surrey University. Dr Lanham-New specialises in Vitamin D and it’s effects on the body, as well as bone health. It was there that I was made aware of vitamin K benefits to the body, in particular the bones.
[You can find one of Dr Susan Lanham-New’s papers HERE].
Vitamin K bone health
It is now estimated that 1 in 3 women and 1 in 12 men will suffer from osteoporosis after the age of 55 (that’s roughly 3 million people). The good news is that we know many lifestyle and dietary changes that can significantly delay, or even prevent, the onset of osteoporosis. For instance, calcium supplementation appears effective for women with a low calcium intake from their diet, and low vitamin D status.
[Calcium supplementation in women, who do in fact consume sufficient calcium from their diet, or those with optimal vitamin D level, is less effective].
In addition, vitamin D3 supplementation also significantly reduces the rate of fractures and falls in the elderly, and helps delay osteoporosis. Where non-significant findings are found, however, regarding vitamin D supplementation, it’s thought to be because the dose of vitamin D was not high enough. [We now know that 2000/2500 IU per day is a sufficient and optimal for most people, with even higher doses being both safe and effective].
[In addition to calcium and vitamin D3 supplementation, more and more data is showing just how effective resistance training is at delaying both osteoporosis and sarcopenia – age-related loss of muscle mass.]
So what are the mechanisms by which vitamin D3 works? Well, vitamin D3 stimulates bone formation and bone maturation, and also helps the absorption of calcium from the gut. It also increases the activity of one of the cells involved in bone metabolism – osteocalsts – and helps in the repair and remodelling of bone. Therefore, a healthy intake of both vitamin D3 and calcium are key to the formation of healthy and robust bones.
In addition to vitamin D3 and calcium intake, vitamin K was thought to be involved in bone metabolism due to observational findings of greater bone mineral density with a greater intake of vitamin K. For example, in a sample of Japanese men, those individuals who reported a greater intake of natto – a prominent source of vitamin K – tended to have significantly higher bone mineral densities. Until recently, no intervention studies had been carried out, however, despite the suspicion that vitamin k benefits bone health.
In a study by Bram et al. 2003 a group of healthy, post-menopausal women receiving a mineral supplement (daily) containing 1 mg vitamin K1 showed reduced bone loss after a 3-year period. This finding was in comparison to a group of women taking no supplement, and a group of women taking the mineral supplement without the vitamin K1. [The mineral supplement contained: calcium, zinc, magnesium, vitamin D]
There are many different types of vitamin K, and the study above used the K1 variety. Therefore, the effect of one specific type may differ from another. Due to the finding that vitamin K1 tends to accumulate in the liver, it has since been suggested that vitamin K benefits are greater with the K2 variety, with the purpose of enhancing bone strength and/or bone mineral density, and preventing loss of bone strength and/or bone mineral density. A study by Knapen et al 2007 found that hip bone strength was retained in women receiving 45 mg per day of vitamin K2, whereas it decreased in those taking the placebo (where a substantial loss of bone strength recorded).
More recently, Knapen et al. 2013 used vitamin K2, but this time used the MK-7 version, having previously used MK-4. This time they found a significantly decreased age related decline in bone mineral density and bone strength over a three year period. They therefore concluded that low-dose MK-7 supplementation (180 mcg) may be beneficial for post-menopausal women.
Benefits of vitamin k
Although findings are not nearly a ‘slam dunk’, there does appear to be evidence that vitamin K supplementation helps delay/attenuate the accelerated decline in bone strength and/or bone mineral density in elderly men or post-menopausal women.
Senior Japanese men who consume natto frequently tend to have better bone health. The finding that natto consumption correlates with bone health could be due to other factors, however, and not just down to natto itself. In addition, intervention studies have shown that vitamin K supplementation, of the K1 or K2 variety, has helped maintain bone strength and/or density in post-menopausal women, where one would otherwise expect to see a natural decline.