Sufficient calcium intake and adequate serum vitamin D level are essential factors in maintaining optimal function of body organs and systems.
However, the national nutritional survey of Japan in 2013 raised concerns about calcium nutrition, said a review from the International University of Health and Welfare in Tokyo, Japan.
According to a 2001 study, the calcium requirements in young and old Japanese women were calculated as 543 and 788 mg/day respectively.
However, the current daily calcium intake for most people in Japan has decreased to around only 480mg a day.
What’s more, a considerable number of osteoporosis patients and postmenopausal women have insufficient serum 25(OH)D (vitamin D) levels, said the review.
For vitamin D, the suggested intake amount is from 50-70 nmol/L.
The review found a number of factors affecting the amount of calcium and vitamin D intake in Japan.
For example, from 2000-2006, calcium intake was around 550mg a day, but this trend stopped in 2007 when Japan launched a national promotion against metabolic syndrome and encouraged people to lose weight. The national nutrition survey in 2008 also recommended reducing calcium intake to 500mg or less.
Another factor is the perception that vitamin D is associated to getting darker skin, researchers wrote, and this could be why a number of women said they do not take adequate amounts of vitamin D. Asian dietary habits also contributed to decreased calcium and vitamin D intake.
Therefore, the review suggested supplementation for these two nutrients would be the best solution to balance out deficiencies, as shown in other Asian countries.
They pointed to a study in Vietnam, where a community-based nutrition education of calcium intake was effective in increasing bone mass and reduced secondary hyperparathyroidism in postmenopausal women. In this prospective study, the postmenopausal women with low calcium intake (<400 mg/day) were educated to increase calcium intake to around 600 mg/day for 18 months.
Also, a recent prospective cohort study in Australia revealed that the group with higher calcium intake of approximately 1000-1300 mg/day, resulted in various health benefits other than fracture prevention such as decrease in all causes of death, non-fatal cardiovascular disease and stroke, researchers said.
Meanwhile in Korea, researchers concluded that a calcium intake of at least 668 mg/day and serum 25(OH)D level of at least 50 nmol/L may be needed to prevent secondary hyperparathyroidism.
"In conclusion, Asian populations are evidently under calcium deficient. The mean calcium intakes in Japan and Korea were approximately 500 mg/day or less," concludes the review.
"Although increased calcium intake from food or supplementation did not improve fracture incidence in Caucasian populations, fracture occurrence in Japanese women after the intervention of calcium nutrition had achieved to decrease in incident fracture. Thus, the calcium intake should be increased to 600 mg/day in populations with a low calcium level (<400 mg/day)."
Source: Osteoporosis and Sarcopenia
“Recent nutritional trends of calcium and vitamin D in East Asia”
Authors: Hiroaki Ohta, Kazuhiro Uenishi et al