Health benefits of Garlic

1. Health Benefits of Garlic
Pennington Biomedical
Research Center
Division of Education
Heli Roy, PhD
Shanna Lundy, BS
Phillip Brantley, PhD, Director

2. PBRC 7/05 2
History
 The potency of garlic has been acknowledged for >500 years.
 In ancient times, garlic was used as a remedy for intestinal disorders,
flatulence, worms, respiratory infections, skin diseases, wounds,
symptoms of aging, and many other ailments.
 Through the middle ages into World War II, the use of garlic to treat
wounds surfaced repeatedly.
 It was ground up or sliced and was applied directly to wounds to inhibit the
spread of infections.

3. PBRC 7/05 3
History
 To date, >3000 publications from all over the world have
gradually confirmed the traditionally recognized health
benefits of garlic.
 Favorable experimental and clinical effects of the
consumption of garlic preparations (including garlic extract)
have been reported.

4. PBRC 7/05 4
 Biological responses include:
 Reduction of risk factors for cardiovascular diseases and cancer
 A stimulation of immune function
 Enhanced foreign compound detoxification
 Radioprotection
 Restoration of physical strength
 Resistance to various stresses and potential anti-aging effects

5. PBRC 7/05 5
Extraction
 It has long been known that extraction of a food can increase its
potency and eliminate unpleasant characteristics.
 The irritating, acidic and oxidizing compounds in raw garlic can be
eliminated or modified by extraction.
 Many of the adverse reactions to garlic can be attributed to an
excess of oil-soluble organosulfur constituents.
 Water-soluble sulfur compounds, which are effective at reducing
cholesterol, were not cytotoxic.

6. PBRC 7/05 6
Garlic preparations
 Have been shown to exhibit hypolipidemic, antiplatelet, and
procirculatory effects
 Aged garlic extract (AGE) has been reported to possess
hepatoprotective, immune-enhancing, anticancer and
chemoprotective activities.
 In addition, AGE exhibits antioxidative activities, whereas raw or
heated garlic stimulates oxidation.

7. PBRC 7/05 7
Reports on Garlic
 Several clinical reports, including meta-analyses, have
revealed a cholesterol-lowering effect of garlic in humans,
prompting public awareness about the cholesterol-lowering
effects of garlic.
 Recent publications suggest that not all preparations may
be hypocholestrolemic, causing confusion with both the
public and the academia.
 The cause of this is likely to be related to the components
present in the preparation, the quantity of the preparation
provided and/or the duration of the study.

8. PBRC 7/05 8
Facts on Garlic
 According to the USDA National Agricultural Statistics Service, the
amount of garlic produced in the United States in 1998 was ~252,000
metric tons.
 Over 60% of the garlic consumed worldwide is produced in California.
 Garlic products have experienced increasing popularity in the last decade.

9. Of 91 herbal
supplements, garlic
was found to be used
more than twice as
much as other
supplements.
Top Supplements Used by US Households in 1997

10. PBRC 7/05 10
Intake of Garlic?
 The appropriate amount is yet to be determined
 The German Kommission E monograph (1988) proposed a daily
intake of ~1-2 cloves of garlic or ~4 g of intact garlic per day for
health benefits
 However, there was no scientific evidence to back this
recommendation.

11. PBRC 7/05 11
Garlic supplements
 Essential oil
 Dehydrated powder
 Oil macerate
 Extract

12. PBRC 7/05 12
Essential Oil
 Garlic essential oil is obtained by steam distillation of garlic
 The essential oil content of garlic cloves is 0.2-0.5% and consists
of a variety of sulfides.
 Commercially available garlic oil capsules generally contain
vegetable oil and a small amount of garlic essential oil because of
pungent odors.

13. PBRC 7/05 13
Dehydrated Powder
 Garlic powder is mass-produced as a flavoring
agent for condiments and processed foods.
 Garlic cloves are sliced or crushed, dried and
pulverized into powder.
 Garlic powder is thought to retain the same
ingredients as raw garlic; however, the proportions
and amounts of various constituents differ
significantly.

14. PBRC 7/05 14
Oil Macerate
 Oil macerates were originally developed for use as condiments.
 Oil macerate products are made of encapsulated mixtures of whole
garlic cloves ground into vegetable oil.

15. PBRC 7/05 15
Extract
 For garlic extract, whole or sliced garlic cloves are
soaked in an extracting solution (purified water
and diluted alcohol) for varying amounts of time.
 After separation of the solution, the extract is
generally concentrated and used.
 Powdered forms of the extract are also available.
 The extract, especially AGE, contains mainly the
water-soluble constituents in garlic and a small
amount of the oil-soluble compounds.

16. PBRC 7/05 16
Aged Garlic Extract
 As the name implies, this extract is aged for up to 20 months.
 Over this time, the harsh and irritating compounds in garlic are
converted naturally into stable and safe sulfur compounds.
 Aged garlic extract contains primarily water-soluble sulfur compounds
such as SAC and SAMC, as well as a variety of oil-soluble sulfur
compounds.
 The safety of AGE has been confirmed by various toxicological studies.

17. PBRC 7/05 17
Bioavailability of garlic compounds
 SAC is one of the water-soluble organosulfur compounds in garlic,
whose concentration can be detected in the plasma, liver, and kidney
after oral intake.
 Its concentration increases during extraction/aging.
 The pharmokinetics of SAC are well-established.
 Its bioavailability in mice is 103.0%, in rats 98.2%, and in dogs
87.2%.

18. PBRC 7/05 18
 From several studies, SAC has proven to be a stable, odorless, water-
soluble compound with the ability to lower cholesterol, serve as an
antioxidant, inhibit the cancer process, and protect the liver from toxins.
 AGE has shown cholesterol-lowering effects in several clinical studies
 At present, SAC is the only reliable human compliance marker used for
studies involving garlic consumption because it is detectable and
increases quantitatively in the blood after oral intake of garlic capsules.

19. PBRC 7/05 19
 The oil-soluble organosulfur compounds in garlic, including allicin,
sulfides, ajoene, and vinyldithiins are not found in the blood or urine
after garlic consumption.
 They are not likely to be the active compounds.
 The instability and/or metabolism of such compounds likely
contribute to the inconsistent results found in the clinical cholesterol
studies using garlic oil and garlic powder products.

20. PBRC 7/05 20
 Prevention, rather than in therapy, is where the effectiveness of garlic
probably lies
 However, to obtain the preventative benefits of garlic, long-term
supplementation may be necessary
Safety Issues

21. PBRC 7/05 21
Safety Issues
 Although garlic has been used safely in cooking as a popular
condiment or flavoring and used traditionally for medicinal purposes,
it is commonly known that excessive consumption of garlic can cause
problems.
 Garlic odor on breath and skin and occasional allergic reactions
are recognized.

22. PBRC 7/05 22
 Reports since 1932 have revealed the following adverse effects
associated with raw garlic and garlic powder:
 Stomach disorders and diarrhea
 Decrease of serum protein and calcium
 Anemia
 Bronchial asthma
 Contact dermatitis
 Inhibition of spermatogenesis

23. PBRC 7/05 23
 Oil-soluble sulfur compounds are known irritants and allergens
 Topically applied diallyl-sulfide (DAS) is the most allergenic
 The following toxicity effects of garlic were reported in 1990:
 Allicin is one of the major irritants in raw garlic
 Oil soluble sulfur compounds are more toxic than water-soluble
 When garlic is extracted in a certain period, its toxicity is greatly reduced

24. PBRC 7/05 24
 On the other hand, the safety of AGE has been well established by
the following studies:
 Acute and subacute toxicity tests
 Chronic toxicity tests
 Mutagenicity tests
 General toxicity tests
 Teratogenicity tests
 Toxicity tests conducted by the USDA
 Clinical studies conducted on >1000 subjects

25. PBRC 7/05 25
SAC versus DADS
 The United States
National Cancer Institute
tested the toxicity of SAC
vs. other typical garlic
compounds and found
that it has a 30-fold less
toxicity than allicin and
diallyl-disulfide (DADS)
The 50% lethal oral dose for each in
mg/kg body weight
Allicin DADS SAC
Male 309 145 8890
Female 363 130 9390

26. PBRC 7/05 26
References
 Harunobu A, et al. Journal of Nutrition. 2001. 131(3):955-962.
Available at: www.nutrition.org/cgi/content/full/131/3/955S