Is sunshine and what would likely amount to UVB exposure the best way to build bone mass? If not, and if there are more sensible/effective ways to increase Bone Mass or Bone Mineral Content or Bone Mineral Density through diet/exercise/other then please provide sound data (clinical studies).
The authors' previous investigations have disclosed low serum 25-hydroxyvitamin D (25-OHD) concentrations in 45 patients during long-term hospitalization following stroke (mean 5.9 ng/mL). This 25-OHD deficiency resulted from sunlight deprivation.
To evaluate the efficacy of sunlight exposure in increasing serum 25-OHD, in reducing the severity of osteoporosis in bone mineral density (BMD), and in decreasing the risk of hip fractures in chronically hospitalized, disabled stroke patients.
In a 12-month randomized and prospective study of stroke patients, 129 received regular sunlight exposure for 12 months, and the remaining 129 (sunlight-deprived) did not.
At baseline, patients of both groups showed vitamin D deficiency. BMD increased by 3.1% in the sunlight-exposed group and decreased by 3.3% in the sunlight-deprived group (p = 0.0001). 25-OHD level increased by fourfold in the sunlight-exposed group. Six patients sustained hip fractures on the hemiplegic side in the sunlight-deprived group, and one hip fracture occurred among the sunlight-exposed group (p = 0421; odds ratio = 6.1).
Sunlight exposure can increase the BMD of vitamin D-deficient bone by increasing 25-OHD concentration.
Please find the study here: Amelioration of osteoporosis and hypovitaminosis D by sunlight exposure .
Invention studies using high dose vitamin K2 show about half of what you're describing with simply sunlight.
I know I've also seen a study (I don't collect nutrition studies like I collect research for my work!) that showed a significant gap between plant and animal sourced protein in bone density (animal being superior to plant).
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