Other Common Healing Approaches 599system (Gunning, 1999), such as inducing cytokine produc-
tion (Bruger, Torres, Warren, Caldwell, & Hughes, 1997) or
enhancing cellular immune function of peripheral blood
mononuclear cells (See, Broumand, Sahl, & Tilles, 1997). In
their review, Barrett et al. (1999) highlight the dif“culty in
comparing the research studies because different species are
studied and there are no universally accepted standardization
procedures.
Garlic
Although commonly considered a food substance, garlic
(Allium sativum) is a commonly prescribed supplemental
herb for the treatment of high cholesterol. Allicin is consid-
ered the active compound found in the garlic bulb. Many of
the studies investigate Kwai garlic powder tablets because it
is standardized for alliin content (1.3% by weight). While
Kleijnen, Knipschild, and ter Riet (1989) suggest that early
studies on the ef“cacy of garlic were methodologically
”awed, more recent studies suggest garlic is ef fective in treat-
ing hypercholesterolaemia. Two meta-analyses (Silagy &
Neil, 1994; Warshafsky, Kamer, & Sivak, 1993) suggest that
garlic reduces the high serum cholesterol levels considered to
be a risk factor for coronary artery disease. Warshafsky et al.
(1993) found 13 studies to meet their methodological criteria,
and meta-analytic results suggested that garlic signi“cantly
lowered cholesterol levels by about 9% in the experimental
groups as compared to placebo. The results of Silagy and
Neil•s (1994) meta-analysis of the 16 trials meeting their
standards for methodological quality found that garlic low-
ered serum cholesterol over one to three months and did not
produce signi“cantly more adverse ef fects. While several au-
thors (Isaacsohn et al., 1998; Jain, Vargas, Gotzkowsky, &
McMahon, 1993) criticized these early meta-analytic “nd-
ings, more recent, randomized, controlled trials have found
garlic to reduce ratios of serum total cholesterol (Adler &
Holub, 1997) and decrease low-density lipoprotein cho-
lesterol in healthy men (Jain et al., 1993; Steiner, Khan,
Holbert, & Lin, 1996).
Ginger
Zingiber officinale,commonly known as ginger, has been pri-
marily investigated for its antiemetic effects. This research
has been particularly important for individuals who suffer
from motion sickness and from postoperative nausea, or
who experience nausea and vomiting due to chemotherapy
but are unable to take synthetic drugs because of side effects
such as sedation and visual disturbances. Several early studies
found ginger to be more effective than placebo in alleviat-
ing gastrointestinal symptoms of motion sickness (Mowrey
& Clayson, 1982), reducing symptoms of seasickness
(Grontved, Brask, Kambskard, & Hentzer, 1988), reducing
nausea (Bone, Wilkinson, Young, McNeil, & Charlton, 1990)
and reducing the request for antiemetics (Phillips, Ruggier, &
Hutchinson, 1993) in postoperative patients. In addition, gin-
ger has been studied for its antitumor effects (Koshimizu,
Ohigashi, Tokudo, Kondo, & Yamaguchi, 1988). Vimala,
Norhanom, and Yadav (1999) demonstrated that some, but
not all, types of ginger inhibit Epstein Barr virus (EBV) acti-
vation without the cytotoxicity effects. The authors suggest
that populations with a high risk of cancer are •encouragedŽ
to take plants with ginger, yet they also acknowledge that
such use will not completely eliminate the disease.Ginkgo BilobaGinkgo biloba extract is derived from the maidenhair tree and
has been studied primarily for its effect on the brain, demen-
tia, and Alzheimer•s disease. Active ingredients include
Egb 761 (tapenoids), which have platelet-activating factor
antagonistic properties, and gingkolides and ”avanoids
(Oken, Storzbach, & Kaye, 1998). Three of the most popular
preparations used in controlled trials include Tebonin,
Tanakan, and Rokan, all of which are different names for the
extract Egb 761. Various products available to the public
contain different amounts of ginkgo biloba extract. In their
review of the literature, Itil and Martorano (1995) suggest
ginkgo has been •proven effectiveŽ in the treatment of tinni-
tus, sudden hearing loss, retinal damage, arthritic symptoms,
vertigo, water retention, circulatory dysfunction, and age-
related dementia. Early studies demonstrated the ef“cacy of
Egb 761 on reducing the negative effects of experimentally
induced stress on rats (Hasenohrl et al., 1996; Porsolt, Martin,
Lenegre, Fromage, & Drieu, 1990; Rapin, Lamproglou,
Drieu, & Defeudis, 1994) over other depressive medications
(Porsolt et al., 1990) and over placebo (Porsolt et al., 1990;
Rapin et al., 1994; Rodriguez de Turco, Droy-Lefaix, &
Bazan, 1993). For instance, Rapin et al. (1994) found Egb
761 to decrease plasma hormone levels such as epinephrine,
norepinephrine, and corticosterone. Alternatively, in their
critical review of 40 controlled trials on Ginkgo and cerebral
insuf“ciency in humans, Kleijnen and Knipschild (1992)
found that only eight trials met criteria of good methodology,
with only one showing positive effects compared with
placebo on symptoms such as dif“culty concentrating,
memory problems, confusion, lack of energy, tiredness, de-
pressive mood, anxiety, dizziness, tinnitus, and headaches.
Similarly, a more recent meta-analysis of more than 50 arti-
cles (Oken et al., 1998) found only four studies (Hofferberth,