Adding vitamin K to a bone health program

Vitamin K1, known as phylloquinone, is made by most plants and is found in high amounts in green leafy vegetables. Vitamin K2, a form of vitamin K found in meat, cheese, and some other foods, is actually a group of fat-soluble vitamins known as menaquinones.

The study, published in Calcified Tissue International, included 173 healthy postmenopausal women who were divided into four groups: a calcium-plus-D group, a K1 group, a K2 group, and a control group. Everyone except the control group received diet and lifestyle counseling, as well as fortified milk and yogurt products providing 800 mg of calcium and 400 IU (10 mcg) of vitamin D per day. The fortified dairy foods given to the K1 group also included 100 mcg of vitamin K1 per day, and those given to the K2 group had 100 mcg of vitamin K2. The control group ate their usual diet throughout the study.

Vitamin K assists calcium-plus-D

After one year, there were several significant differences between the groups:

• Total body bone mineral density improved more in the three supplemented groups than in the control group. People with higher bone density generally have a lower fracture risk.
• Compared to the women in the calcium-plus-D and control groups, the women in the two vitamin K groups had reduced levels of urine and blood markers associated with bone turnover. A lower rate of bone turnover is generally associated with a lower fracture risk.
• The women in the K1 and K2 groups had greater increases specifically in lumbar spine bone density than women in either the calcium plus D group or the control group.

The results of this study suggest that vitamin K, whether as K1 or K2, may add to the beneficial effects of a comprehensive bone health program. The study's authors explain, "The holistic nature of the current intervention and probably the synergistic effect of supplementing nutrients that are essential for bone health . . . together with increasing physical activity levels and improving dietary patterns as a result of counseling sessions could probably provide an explanation for these favorable changes."

Preventing bone fractures

While vitamin K may play a role in maintaining bone density as we age, these results don't tell us for sure whether vitamin K supplements can contribute to fracture prevention. Here are some other strategies that have been shown to prevent bone fractures:

• Stay balanced. Preventing falls can prevent fractures. Wear comfortable shoes that have some grip and make walking easy, even in the house--socks and slippers can be slippery. Balance training exercises such as tai chi and yoga can improve stability.
• Stay fit. Engaging regularly in weight-bearing exercises like walking, dancing, and jogging can help prevent fractures by building bone, increasing muscle strength, and improving balance. Try to get 30 minutes of physical activity per day.
• Eat your greens. Vegetables and fruits are rich in nutrients that support bone health including magnesium, potassium, and vitamin K. Several studies have found that people who eat a diet high in fruits and vegetables are less likely to experience a bone fracture.
• Check your protein intake. People whose diets are deficient in protein have a higher fracture risk. You can get enough protein by including some nuts and seeds, beans or soy foods, and whole grains every day; adding a few ounces of fish, eggs, dairy, chicken, or meat from time to time should ensure your protein intake is adequate. But, be careful not to overdo, since excess dietary protein can contribute to calcium loss from bones.

Finally, if you take a blood thinning medication and you're considering adding a bone-building supplement that includes vitamin K, be sure to talk to your doctor before you start.

(Calcif Tissue Int 2012;90:251-62)