TABLE 3.

Aspects to consider when reviewing RCTs assessing the effect of PUFA intake and bone health¹

Inclusion criteria	Participant characteristics: age, sex, ethnicity, BMI, physical activity, and previous fracture incidence are all variables that modulate bone health
	Menopausal status: bone turnover is largely imbalanced during the 5- to 10-y period coinciding with the menopausal transition, with different rates of bone loss occurring at different skeletal sites (94)
	HRT use: dietary fats may act in concert with exogenous estrogens
	Anti-fracture medication: drugs such as bisphosphonates or selective estrogen receptor modulators will impact the efficiency of a nutritional intervention
Baseline dietary patterns	Habitual PUFA intake and supplement use: lifelong exposure to certain PUFAs may impact the ability of an intervention to alter bone health above a threshold
	Baseline calcium and vitamin D: most RCTs provide all groups with calcium and vitamin D supplements, which may mask any additional effect of an intervention if baseline values are lower than recommended
Intervention	PUFA intervention: PUFA type and source (food or supplement), PUFA amount, PUFA ratio
	Study length: experimental intervention must be of sufficient duration to detect changes in the primary outcome measure
Primary outcome measure	Imaging technique used: BMD by DXA, 3-dimensional quantification of bone structure and strength by HR-pQCT
	Site-specific effects: regions of the skeleton may not respond uniformly to an intervention (e.g., hip, lumbar spine, appendicular limbs)
	Biochemical markers of bone turnover: including circadian variation of markers, sampling in a fed or fasted-state, intra-individual variability. To reduce variability, it is useful to measure multiple markers as well as the longitudinal change in markers in the same subject over time

¹BMD, bone mineral density; HR-pQCT, high-resolution peripheral quantitative computed tomography; HRT, hormone replacement therapy; RCT, randomized controlled trial.