Health Benefits of Garlic

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Health Benefits of Garlic

• Pennington Biomedical
• Research Center
• Division of Education

Heli Roy, PhD Shanna Lundy,
BS Phillip Brantley, PhD, Director
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History

• The potency of garlic has been acknowledged for
  gt500 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.

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History

• To date, gt3000 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.

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• 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

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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.

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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.

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Reports on Garlic

• Several clinical reports, including
  meta-analyses, have revealed a cholesterol-lowerin
  g 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.

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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.

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

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Garlic supplements

• Essential oil
• Dehydrated powder
• Oil macerate
• Extract

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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.

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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.

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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.

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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.

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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.

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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.

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• 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.

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• 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.

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Safety Issues

• 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

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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.

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• 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

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• 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

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• 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 gt1000 subjects

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SAC versus DADS
The 50 lethal oral dose for each in mg/kg body
weight

• 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)

Allicin DADS SAC
Male 309 145 8890
Female 363 130 9390
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References

• Harunobu A, et al. Journal of Nutrition. 2001.
  131(3)955-962. Available at www.nutrition.org/cg
  i/content/full/131/3/955S