Vitamin Information Center

NEW YORK (Reuters Health) - Softening of the skull bones in normal-appearing newborns is tied to a vitamin D deficiency in the womb, according to Japanese researchers.

They suggest that breast-fed infants with this condition may need vitamin D supplements.

Soft skull bones, also known as craniotabes, in normal newborns is usually regarded as no cause for alarm, but Dr. Tohru Yorifuji at Kyoto University Hospital and colleagues dispute this in their report in the Journal of Clinical Endocrinology and Metabolism. They point to evidence that the condition is associated with type 1 diabetes, reduced bone mass during childhood, and lowered immunity.

In their study, the researchers screened 1120 normal infants at 5 to 7 days of age. Craniotabes was considered present when “the skull bones reversibly bended by application of pressure by the examiner’s fingers.”

They found that 246 babies, or 22 percent, had craniotabes. The highest rate occurred among infants born in April and May, and the lowest in those born in November.

Vitamin D production in the body is triggered by sunlight, and Yorifuji’s team points out that the rate of craniotabes “was influenced by the daylight hours approximately 4 months prior to delivery.” They say this strongly suggests that “the condition is associated with vitamin D deficiency in utero.”

Low vitamin D levels and other abnormalities at 1 month of age were more common in babies who were breast-fed than in those who were fed formula at least part of the time, the investigators found.

They therefore recommend “treating breast-fed infants with craniotabes with vitamin D, or preferably, treating all pregnant women with vitamin D.”

SOURCE: Journal of Clinical Endocrinology and Metabolism, online February 12, 2008.

New research has concluded vitamin K2 consumption can aid recovery from hip fractures as well as have potential osteoporosis benefits.

Published in the European Journal of Epidemiology, Japanese researchers found a positive link between vitamin K2 and hip fractures and osteoporosis, and suggested a review of the, “dietary reference value of vitamin K from the perspective of osteoporosis would be useful.”

The current Japanese reference value is 55mcg for women and 65mcg per day for men. In the US and Canada it is 120mcg per day for men and 90mcg per day for women. In France the limit is 65mcg per day for both men and women.

“Since regions which consumed a lot of vitamin K, especially vitamin K2, showed a low incidence of hip fracture, we considered that vitamin K intake, not absorption, of over 300 mcg/day would be helpful to reduce the incidence of hip fracture,” the researchers concluded.

Family K

The vitamin K family includes the forms phylloquinone (K1) that are typically found in cruciferous vegetables and menaquinone (K2), which are sourced from bacteria. Studies have shown K2 to be the more important nutrient in regard to bone health.

“Menaquinone-7 (K2) showed a very long half-life time compared to vitamin K1,” the researchers wrote. With this in mind they recommended higher doses in regions like Europe and North America, where vitamin K1 consumption is higher.

The study also investigated vitamin D, calcium and magnesium, which have strong clinical bone health backing, and found when these were adjusted for, vitamin K2 continued to reveal a beneficial effect.

Dietary sources

The study assessed population diets in various regions of Japan as well as dietary differences, and found that those regions where certain vitamin K-rich fruits and vegetables were prominent had reduced rates of hip fracture.

“There was also a striking pattern of high intake of vitamin K and low incidence of hip fracture in eastern areas of Japan, with the opposite pattern-a low intake of vegetables rich in vitamin K and a high incidence of hip fracture-in western areas,” they wrote.

“These findings lend support to the idea that vitamin K is an important factor explaining regional differences in the incidence of hip fracture.”

Natto, a food made from fermented soy beans, was singled out as being a particularly abundant vitamin K source.

K for bones

The researchers recognised that the role of Vitamin K role in assisting bone health is relatively new.

“Calcium, the most studied nutrient in the area of bone health, is known for its effectiveness in retarding bone loss in postmenopausal women,” they said. “Magnesium and vitamin D play important roles in calcium and bone metabolism. Vitamin K, originally recognised as a factor required for normal blood coagulation, is beginning to receive more attention for its role in bone metabolism.”

Due to the ecological nature of the study, a “causal linkage between the incidence of hip fracture and intake of vitamin K” could not be confirmed but the researchers said, “further research using more robust epidemiological methods is warranted.”

Estimates suggest that in the absence of primary prevention the number of hip fractures worldwide will increase to approximately 2.6 million by the year 2025, and 4.5 million by the year 2050.

Osteoporosis weakens bone strength which increases the likelihood of hip fracture, a problem that increases with age.