by Craig Weatherby
As Vital Choices readers know, there is growing evidence that vitamin D may be more important than calcium when it comes to bone health.
Dr. Andrew Weil makes the point in the current (March 20) issue of “Time” magazine: “…last month's Women's Health Initiative (WHI) report suggested that calcium pills offer only modest, if any, protection [against hip fractures in post-menopausal women]. I believe that supplemental vitamin D is more important than supplemental calcium. If you are getting enough vitamin D, particularly in early life, you should absorb calcium from foods efficiently.”
The recently published WHI clinical trial to which Dr. Weil refers tested the fracture-prevention potential of supplemental calcium and vitamin D in women aged 50-79.
The generally negative headlines reporting its results ignored the fact that most of the women did not take the calcium and vitamin D pills as prescribed, and ignored the substantial body of prior evidence that supports the bone-health benefits of even higher dietary intake of vitamin D (see “Women's Bone-Health Study Yields Fractured Results”).
The media reports also downplayed the positive outcome among the women who actually took most of their prescribed calcium and vitamin D pills, who enjoyed a 29 percent reduction in the risk of hip fractures.
And, the women in the WHI trial only took 400 IUs of vitamin D per day. This is the current RDA for vitamin D, but it is an amount considered inadequate by experts in the field.
As Dr. Weil wrote in his Time article on bone health, “What is enough? I recommend at least 1,000 IUs daily taken with a fat-containing meal.”
Salmon, sardines, tuna, and other fatty fish fit that bill perfectly, as they are rich in vitamin D and healthful fatty acids (see our sidebar titled “Fish fit the bone-building bill”).
When it came to recommending food sources of calcium i his "Time" article, Dr. Weil was bullish on fish, but skeptical about the value of milk: “Calcium-rich foods include dark, leafy greens, broccoli, sesame seeds, canned sardines and salmon mashed up with the bones, cooked dried beans, soy foods and, of course, milk. But I agree with Harvard's Walter Willett and others that dairy products are not the preferred sources. In the Nurses' Health Study, Willett found that postmenopausal women who drank two glasses of milk a day were no better protected against bone fractures than women who drank a glass or less a week.”
Bone-building begins early
Researchers' tendency to focus on bone-building nutrition in mature women is both understandable—they're the group at greatest risk of fractures—and a bit of a red herring.
For one thing, exercise is a key determinant of bone strength, assuming minimally adequate amounts of four bone-building nutrients: calcium (1,300 mg/day), magnesium (400-500 mg/day), vitamin D (1,000 IU/day), boron (500 mcg to 3 mg/day), and marine omega-3s (1,000 mg/day).
And, while post-menopausal women suffer the greatest risk of falls and resulting hip fractures, a woman's best opportunity to build strong bones occurs before her first menstrual period (menarche).
In other words, it's relatively easy for women to build and keep healthy bones for life if they engage in weight-bearing exercise and get good bone nutrition before they begin menstruating, and then continue exercising and eating right throughout life.
This is not to say that women can't strengthen weak bone in middle age or later—they certainly can—but it is considerably harder. Success is less assured and may depend on drugs like alendronate (Fosamax), which bring marginal bone-density benefits and may elicit undesirable side effects.
And findings from a new clinical trial support Dr. Weil's emphasis on getting enough vitamin D in early life.
Study in girls shows vitamin D can confer big bone-muscle benefits
The results of a new study show that girls who take high doses of supplemental vitamin D before the onset of menstruation may build more bone and muscle mass, compared with girls with lower vitamin D intake.
The study was a double-blind, placebo-controlled trial that lasted a full year, and involved 179 girls aged 10–17.
The girls were randomly assigned to receive one of two weekly doses of supplemental vitamin D: the “low-dose” group took 1,400 IU per week (equivalent to 200 IU/day) while the second, “high-dose” group took 14,000 IU (equivalent to 2,000 IU/day).
At the beginning and end of the year-long study, the researchers measured the girls' bone mineral density (BMD) and bone mineral content (BMC) overall and in the lumbar spine, hip, and forearm. They also measured the girls' body composition (ratio of muscle to fat).
The results suggest that taking high-dose vitamin D before the first menstrual period may confer lifelong bone-strength benefits:
- The pre-menstrual girls in the high-dose vitamin D group showed the greatest increases in total bone mass and mineral content in hip bones.
- Pre-menstrual girls in both vitamin D groups (high- and low-dose) enjoyed increases in bone mineral density and/or mineral content at several places.
- Post-menstrual girls showed no significant changes in bone mineral density or mineral content.
- All the girls—pre-menstrual and post-menstrual—showed significant increases in muscle mass.
As the researchers concluded, “Vitamin D replacement [supplementation] had a positive impact on musculoskeletal parameters [measurements] in girls, especially during the premenarcheal [pre-menstrual] period.”
These findings dovetail with Dr. Weil's advice to take high-dose vitamin D, which he followed with another good recommendation: “The teens and twenties are good times for men and women to start strength training. Working out with weights a few times a week builds bones and muscle mass, which you'll thank yourself for as you age.”
- El-Hajj Fuleihan G, Nabulsi M, Tamim H, Maalouf J, Salamoun M, Khalife H, Choucair M, Arabi A, Vieth R. Effect of vitamin D replacement on musculoskeletal parameters in school children: a randomized controlled trial. J Clin Endocrinol Metab. 2006 Feb;91(2):405-12. Epub 2005 Nov 8.