Page 47 - Today's Dietitian (February 2020)

one study on rats found that garlic oil
extract promotes the transfer of calcium
in the intestines, which may prevent the Register now for
reduced bone density that can lead to
5
osteoporosis. Another study showed our 2020 Spring
that rats treated with garlic oil devel-
oped a significantly lower number of
tumors on their livers when exposed to a Symposium!
compound that causes liver cancer. 6
Aqueous solutions, another common www.TodaysDietitian.com/SS20
liquid preparation of garlic, lead to
the development of water-soluble
organosulfur compounds such as S-allyl-
cysteine (SAC). SAC is most commonly mentioned, AGE contains a high conventional blood pressure medica-
found in aged garlic extract (AGE), the type concentration of SAC, one of the tions, but the differences in medication
of garlic used in several research studies. most bioavailable and least volatile types weren’t significant among par-
Researchers suspect the aging process compounds in garlic. SAC may be able ticipants at baseline. The results of this
transforms the volatile compounds found to lower blood pressure, as it can act as trial were consistent with Ried’s previ-
in raw garlic into more stable substances, an antioxidant and trap reactive oxygen ous studies. The group that received AGE
such as SAC, which may have antioxidant species. SAC also may inhibit the had a significantly lower mean systolic
activity and protect against heart disease increased expression of a transcription blood pressure (5 ± 2.1 mm Hg, p=0.016)
and cancer. 2,8,9 Unlike allicin and the factor that contributes to hypertension at 12 weeks compared with the start of
organosulfur volatiles found in oil-soluble and enhance the production of nitric the trial. These findings suggest that
12
garlic preparations, SAC has been found to oxide, a vasodilator. garlic, especially AGE, may be a safe and
3
be one of the most bioavailable and active Ried and colleagues designed stud- effective adjunct treatment for uncon-
compounds in garlic. 2 ies that test the impact of AGE capsules trolled high blood pressure.
Understanding the complexity of gar- with varying doses of SAC on hyperten-
lic’s chemistry is key to assessing past sion. 8,10-12 In a double-blinded random- Hyperlipidemia
and emerging research about its health ized controlled trial with 50 patients Garlic powder and AGE may provide
benefits. While several factors, including with treated yet uncontrolled hyper- lipid-lowering benefits through at least
study designs, may contribute to the dif- tension, the researchers gave the treat- two suspected mechanisms. Research
fering conclusions about garlic’s poten- ment group 960 mg AGE with 2.4 mg suggests that the organosulfur com-
tial, the variety of forms of garlic used SAC daily for 12 weeks and gave the con- pounds in garlic, especially SAC, may
in studies is one of the factors that most trol group placebos. Every patient in inhibit enzymes involved in cholesterol
13
influences results. In addition, several the trial was taking one or more blood synthesis in the liver. Certain com-
studies were performed on rats, used pressure medications at the time of the pounds in garlic also may stop LDL
varying doses of garlic, and occurred study. The results showed that in con- oxidation. 14
over a short timeline. junction with these medications, AGE Meta-analyses of the existing
This article analyzes the conclu- contributed to a significant decrease in literature on the beneficial effects of
sions of recent literature while consid- systolic blood pressure (10.2 ± 4.3 mm garlic on lipid levels suggest that garlic
ering the form of garlic used to inform Hg, p=0.03) compared with the placebo. preparations can significantly reduce
best practice for the use of garlic to pro- Furthermore, participants tolerated total cholesterol levels. 15,16 Garlic’s
tect against disease. More clinical and AGE well, and the researchers reported efficacy in reducing total cholesterol
10
animal studies, especially those that a 92% acceptability of the treatment. appears to depend on the length and
explore the bioavailability and safety In a similar study, Ried and colleagues type of supplementation. Trials that
of certain garlic compounds alone and found that individuals with uncon- lasted longer than eight weeks and
together, are needed. trolled blood pressure who received those that used AGE show a more
480 mg AGE experienced a significant pronounced cholesterol-lowering effect
Mechanisms of Action reduction in their mean systolic blood of garlic. Results of studies assessing
15
and Health Benefits pressure (11.8 ± 5.4 mm Hg, p=0.006) at the efficacy of garlic in reducing LDL or
The following sections summarize the the 12-week mark compared with their triglyceride levels and increasing HDL
11
current literature on the health effects own blood pressures at baseline. levels offer less clear conclusions.
of garlic and the possible reasons behind Subsequently, Ried and colleagues Sobenin and colleagues analyzed the
these benefits. assessed the effect of an even higher effects of time-released 600 mg garlic
dose of AGE on blood pressure. In powder tablets on the lipid levels of 42
Hypertension this trial, 88 patients with uncon- men who were aged 35 to 70 and had
Researchers who have investigated the trolled hypertension received either slightly high cholesterol levels. The par-
hypotensive effects of garlic mostly 1.2 g AGE with 1.2 mg SAC or a placebo ticipants were randomized into two
have focused on AGE. As previously for 12 weeks. Each patient also took groups that received either the garlic
FEBRUARY 2020 • WWW.TODAYSDIETITIAN.COM 47