Background: Evidence from clinical studies has suggested that cocoa may increase high-density lipoprotein (HDL)-cholesterol concentrations. However, it is unclear whether this effect is attributable to flavonoids or theobromine, both of which are major cocoa components.
Objectives: We investigated whether pure theobromine increases serum HDL cholesterol and whether there is an interaction effect between theobromine and cocoa.
Design: The study had a 2-center, double-blind, randomized, placebo-controlled, full factorial parallel design. After a 2-wk run-in period, 152 healthy men and women (aged 40-70 y) were randomly allocated to consume one 200-mL drink/d for 4 wk that contained 1) cocoa, which naturally provided 150 mg theobromine and 325 mg flavonoids [cocoa intervention (CC)], 2) 850 mg pure theobromine [theobromine intervention (TB)], 3) cocoa and added theobromine, which provided 1000 mg theobromine and 325 mg flavonoids [theobromine and cocoa intervention (TB+CC)], or 4) neither cocoa nor theobromine (placebo). Blood lipids and apolipoproteins were measured at the start and end of interventions.
Results: In a 2-factor analysis, there was a significant main effect of the TB (P < 0.0001) but not CC (P = 0.1288) on HDL cholesterol but no significant interaction (P = 0.3735). The TB increased HDL-cholesterol concentrations by 0.16 mmol/L (P < 0.0001). Furthermore, there was a significant main effect of the TB on increasing apolipoprotein A-I (P < 0.0001) and decreasing apolipoprotein B and LDL-cholesterol concentrations (P < 0.02).
Conclusions: Theobromine independently increased serum HDL-cholesterol concentrations by 0.16 mmol/L. The lack of significant cocoa and interaction effects suggested that theobromine may be the main ingredient responsible for the HDL cholesterol-raising effect. This trial was registered at clinicaltrials.gov as NCT01481389.