Association of source-specific nitrate intake with inflammation and cardiometabolic health: a cross-sectional study

This study aimed to explore whether health effects of dietary nitrate depend on its source, by investigating associations between plant and animal-sourced dietary nitrate groups with markers of inflammation and CVD risk factors. Among 100 non-smoking adults (mean age 49 (sd 13) years, 31 % male), dietary nitrate intake was assessed using FFQ (n 100) and 3-d food diary (n 89), combined with nitrate food composition databases. Nitrate intake was classified into plant, naturally occurring animal and additive-permitted meat-sourced groups. Associations between source-dependent nitrate intakes and lipoprotein-associated phospholipase A2 (Lp-PLA₂), C-reactive protein (CRP), fasting plasma lipids, anthropometry and blood pressure were examined using multivariable linear regression, adjusted for socio-demographic, lifestyle and dietary confounders. Each 1 sd (∼57 mg/d) increment in plant-sourced nitrate intake was associated with a 0·191 sd lower LDL-cholesterol (β = -0·191, 95 % CI (-0·369, -0·004), P = 0·045; equivalent to -0·21 mmol/l) in primary models, though this association was attenuated in sensitivity analyses. Naturally occurring animal-sourced nitrate intake was not associated with any outcomes. A 1 sd (0·08 mg/d) increment in additive-permitted meat-sourced nitrate intake was associated with a 0·208 sd lower HDL-cholesterol (β = -0·208, (-0·362, -0·054), P = 0·009; equivalent to -0·10 mmol/l) and a 0·192 sd higher waist circumference (β = 0·192, (0·005, 0·380), P = 0·042; equivalent to +1·29 cm) but not with LDL-cholesterol, TAG, blood pressure, Lp-PLA₂ or CRP. These preliminary findings suggest potential differential associations between nitrate source and cardiometabolic markers that warrant confirmation in larger studies.