Table 3.

Threshold effect analysis of dietary folate intake and BMD in postmenopausal women

Threshold effect analysis of dietary folate intake and BMD in postmenopausal women
	Adjusted HR (95% CI), P value
Total femur BMD
Fitting by the standard linear model	0.00 (− 0.00, 0.00) 0.267
Fitting by the two-piecewise linear model
Inflection point	566 μg/day
Dietary folate intake < Inflection point	0.00 (0.00, 0.00) 0.013
Dietary folate intake > Inflection point	− 0.00 (− 0.00, 0.00) 0.092
P for log-likelihood ratio	0.017
Femoral neck BMD
Fitting by the standard linear model	0.00 (− 0.00, 0.00) 0.505
Fitting by the two-piecewise linear model
Inflection point	569 μg/day
Dietary folate intake < Inflection point	0.00 (− 0.00, 0.00) 0.053
Dietary folate intake > Inflection point	− 0.00 (− 0.00, 0.00) 0.115
P for log-likelihood ratio	0.040
Trochanter BMD
Fitting by the standard linear model	0.00 (− 0.00, 0.00) 0.384
Fitting by the two-piecewise linear model
Inflection point	528 μg/day
Dietary folate intake < Inflection point	0.00 (0.00, 0.00) 0.004
Dietary folate intake > Inflection point	− 0.00 (− 0.00, − 0.00) 0.024
P for log-likelihood ratio	0.003
Intertrochanter BMD
Fitting by the standard linear model	0.00 (− 0.00, 0.00) 0.337
Fitting by the two-piecewise linear model
Inflection point	566 μg/day
Dietary folate intake < Inflection point	0.00 (0.00, 0.00) 0.042
Dietary folate intake > Inflection point	− 0.00 (− 0.00, 0.00) 0.189
P for log-likelihood ratio	0.057
Total spine BMD
Fitting by the standard linear model	0.00 (− 0.00, 0.00) 0.350
Fitting by the two-piecewise linear model
Inflection point	249.5 μg/day
Dietary folate intake < inflection point	0.00 (− 0.00, 0.00) 0.446
Dietary folate intake > inflection point	0.00 (− 0.00, 0.00) 0.633
P for log-likelihood ratio	0.564

Adjusted for age, gender, race, marital status, PIR, BMI, alcohol consumption, PA, history of hypertension, serum cotinine and serum vitamin D

BMD Bone mineral density