By Jack Norris, RD
Thorpe et al. (2021) published a report from the Adventist Health Study-2 comparing hip fracture rates of different diet groups among white participants only (due to their generally poorer bone health) who were 45 years or older.
Female vegans had a higher risk of hip fracture compared to non-vegetarians (HR 1.55, CI 1.06-2.26). These findings were adjusted for weight and height, but not for body mass index (BMI), so it’s hard to know if the difference is mainly due to the lower BMI of vegans, which has been found in the Adventist Health Study-2 (see Cardiovascular Disease Markers of Vegans: 2013 Report from Adventist Health Study-2).
The findings were also adjusted for total calcium intake and total vitamin D intake, but not for protein intake. The table below shows the intakes of vegans and nonvegetarians.
After adjusting for calcium and vitamin D supplementation together, the researchers found that the vegans no longer had a higher risk of hip fracture. Their conclusion was that without supplementation of both vitamin D and calcium, female vegans are at high risk of hip fracture.
The RDA for vitamin D for people aged 9 to 70 years is 600 IU/day, and for people older than 70 years it’s 800 IU/day. Vegans in this study were only getting about half of the RDA. It’s not possible for most people to obtain the RDA for vitamin D through diet alone without using supplements. Some people will obtain significant amounts of vitamin D by way of direct sunlight, but it isn’t reliable.
Some research has shown that combining calcium and vitamin D supplementation can be beneficial for women over 70 with generally low calcium intake and vitamin D status (see Calcium and Vitamin D Supplements in Elderly Women with Low Vitamin D Levels).
This study provides evidence that vegan women, especially post-menopausal, should strive to meet calcium recommendations of 1,200 mg and vitamin D recommendations of 600-800 IU per day.
We’ve added this study to the VeganHealth article, Calcium: Research.
Thorpe DL, Beeson WL, Knutsen R, Fraser GE, Knutsen SF. Dietary patterns and hip fracture in the Adventist Health Study 2: combined vitamin D and calcium supplementation mitigate increased hip fracture risk among vegans. Am J Clin Nutr. 2021 May 8:nqab095.