Table 4

Direct and indirect effects of low carbohydrate and high fibre diet consumption on markers of CVD risks with BMI, WC and HbA1C as mediators among UK adults aged 45–80 years in NDNS (2008/2009–2016/2017)

Mediator and outcomes	Direct effect		Indirect effect
Mediator and outcomes	Estimate	95% CI	Estimate	95% CI
BMI as mediator (model 1)
HbA1c	0.48	−0.01 to 0.59***	0.33	−0.49 to 0.55***
TRIG	−8.43	−14.61 to −0.61***	4.92	−7.62 to 11.04
Total Chol	−21.46	−25.57 to 12.37***	−9.68	−35.76 to 25.32***
HDL	−2.82	−7.28 to 9.6	−1.2	−16.51 to 10.93
LDL	−8.17	−18.88 to 8.28	−12.0	−26.13 to 17.88***
SBP	−5.08	−9.05 to 0.54***	0.55	−5.57 to 9.36
DBP	−0.64	−6.95 to 1.04	0.22	−6.34 to 6.08
CRP	0.81	−1.21 to 1.86	1.46	−2.51 to 2.48***
BMI and WC as mediators (model 2)
HbA1c	0.38	−0.08 to 0.62***	0.24	−0.54 to 0.58***
TRIG	−3.44	−13.37 to −0.09	6.32	−6.67 to 13.05**
Total chol	−22.24	−25.05 to 14.85***	−10.24	−35.46 to 32.21**
HDL	−6.78	−7.75 to 8.82***	−7.22	−17.31 to 9.4***
LDL	−9.77	−18.16 to 11.18**	−11.48	−24.64 to 25.73***
SBP	−4.91	−9.4 to 1.14***	0.58	−5.9 to 9.29
DBP	−4.4	−6.18 to −0.54***	−0.67	−5.57 to 6.37
CRP	1.28	−0.94 to 1.83	1.23	−2.38 to 2.27**
BMI, WC, HbA1c as mediators (model 3)
HbA1c	NA	NA	NA	NA
TRIG	−3.91	−14.46 to 0.49	8.79	−6.27 to 13.18***
Total Chol	−11.61	−29.13 to 14.58**	−7.31	−34.77 to 24.64
HDL	−3.66	−8.3 to 7.37**	−6.09	−16.57 to 9.07***
LDL	−7.24	−18.01 to 16.64	−7.86	−26.45 to 22.31**
SBP	−6.46	−9.23 to 1.4***	0.53	−4.89 to 10.55
DBP	−2.88	−7.06 to 0.97**	0.45	−5.83 to 6.27
CRP	1.26	−1.07 to 1.61	1.55	−2.52 to 2.33***

The confounders for the analysis are age, sex, ethnicity, economic status, smoking status, total calories intake, alcohol intake and whether taking general medicines.
Indirect effect: the effect of diet on the outcome that is explained by the mediator.
Direct effect: the effect of diet on the outcome that is not explained by the mediator.
**p≤0.05, ***p<0.01.
BMI, body mass index; CRP, C reactive protein; CVD, cardiovascular disease; DBP, diastolic blood pressure; HbA1c, glycated haemoglobin; HDL, high-density lipoprotein ; LDL, low-density lipoprotein; NA, not available; NDNS, National Diet and Nutrition Survey; SBP, systolic blood pressure; TC, total cholesterol; TRIG, triglycerides; WC, waist circumference.