Objective: To test the effect of instant coffee on serum cholesterol.
Design: A randomised controlled cross-over trial. Setting: Free-living
healthy volunteers. Subjects: 312 were recruited, of whom 18 failed t
o complete the trial and a further 33 were excluded because of breache
s of the protocol, giving 261 whose results were analysed. Interventio
n: Five cups of instant coffee daily for 6 weeks, versus no coffee for
6 weeks, the order of these periods being allocated at random. Main o
utcome measures: The primary outcome measure was serum cholesterol con
centration. Other outcome measures were apolipoproteins A-I and B, hig
h-density lipoprotein cholesterol, plasma fibrinogen, mean platelet vo
lume, while blood cell count. Results: A very small increase in serum
cholesterol concentration with coffee (0.12 mmol/l; 95% c.i. 0.04-0.20
, P = 0.003). A correspondingly small rise occurred in the associated
apolipoprotein B (1.69 mg/dl; 95% c.i. 0.40-2.98, P = 0.011). No chang
es attributable to coffee occurred in the other variables measured, al
though serum concentrations of high-density lipoprotein cholesterol an
d the apolipoproteins tended to be higher after the second period of t
he trial than after the first period, for no obvious reason. Conclusio
ns: Instant coffee has only a marginal effect on serum cholesterol.