the garlic-4 group compared with the garlic-2 group may have
been linked to the poorer compliance and lesser tolerability seen
in the garlic-4 group. A dosage of one capsule of aged garlic
extract daily did not lower SBP significantly different to placebo.
In all, 4% of participants (3 out of 79) withdrew from the trial
after 4 weeks because of gastrointestinal complaints, two in the
garlic-4 group and one in the placebo-4 group. Although rare,
gastrointestinal disturbances have been reported in other trials
using therapeutic dosages of garlic by similar proportions of
participants.10,24,25 Lower tolerance of sulphur-containing foods
such as garlic and onion has been linked to genetic variation in
detoxification pathways of sulphur-transferase enzymes, as well as
inflammatory status, and levels of molybdenum and vitamin
B12.26,27
Other minor side effects were reported by a third (32%) of the
participants in the garlic-4 group, and 15% in the garlic-2 and
garlic-1 groups compared with 5% in the placebo group. Minor
side effects included bloating, flatulence and reflux. However,
most side effects were reported in the first week of the trial, and
participants found ways to overcome these, for example, by taking
the trial capsules in the morning rather than in the evening.
Greater tolerability, compliance, acceptance and willingness to
continue and pay for capsules were associated with a lower
dosage and fewer capsules daily.