1. Garlic
can help prevent fatigue
Ancient
civilizations used garlic to prevent fatigue among laborers,
as well as improve their strength and work performance (1).
In the
early Greek states, Olympians were given garlic to ingest in
order to boost their performance.
Several
animal studies have shown that garlic can help enhance
endurance during exercise (2).
In human studies, garlic is effective in improving
conditions of people suffering from physical fatigue, or
fatigue due to cold weather conditions.
One study
showed that garlic oil helped reduce the heart rates in
coronary artery disease patients when they were subjected to
moderate exercise (3).
The study also showed that the patients exhibited higher
tolerance for exercise after the garlic oil was
administered.
Garlic
contains thiamine (vitamin B1) and pyridoxine (vitamin B6)
and studies show that when combined with other nutrients,
thiamine and pyridoxine can help reduce fatigue in patients
with end stage renal disease (4).
Another
study demonstrated that thiamine was an effective
anti-fatigue agent during endurance training (5).
Studies
also show that a deficiency in phosphorus and copper, major
constituents of garlic, is a risk factor in the development
of chronic fatigue syndrome (6,
7).
Bottom Line:
Garlic has been used as an anti-fatigue agent since the
times of the first Greek Olympians. It also contains
thiamine, pyridoxine, copper, and phosphorous, which help
prevent fatigue even in critically ill patients.
2. Garlic
is effective in the treatment and prevention of
cardiovascular diseases
Studies
show that allicin, one of the main compounds found in
garlic, prevents cardiovascular diseases by encouraging
vasorelaxation (8).
In
addition, studies also show that allicin has the potential
of eradicating symptoms and conditions related to
cardiovascular disease (8). These conditions include
hyperglycemia, cardiac hypertrophy, and platelet
aggregation.
The
antioxidant properties of allicin also help it in preventing
and treating CVD by scavenging of free radicals in the body
and encouraging the release of glutathione (8).
Animal
studies have shown that garlic extracts help to reduce
diastolic and systolic pressures, thereby reducing the
chances of hypertension development, which is a risk factor
for cardiovascular diseases (9).
A study
conducted on hypertensive individuals show that garlic is
capable of reducing blood pressure in individuals already
suffering from hypertension (10).
The same
study also shows that garlic has the ability to decrease
slightly elevated cholesterol levels in human beings.
In
addition, researchers have also found that garlic
supplementation can help reduce blood pressure in
individuals with essential hypertension (11).
The same
study illustrated that the garlic compounds helped alleviate
oxidative stress, further offering cardio protection to
these individuals.
Furthermore, one study showed that extracts from aged garlic
helped to lower the blood pressure of individuals suffering
from treated but uncontrolled high blood pressure (12).
Garlic is
also highly effective when it comes to decreasing serum
concentration of total and LDL (bad) cholesterol in subjects
suffering from hypercholesterolemia (13).
It does this without affecting the levels of good
cholesterol, HDL.
Another way
that garlic prevents cardiovascular diseases is by
increasing the HDL levels, and inhibiting the oxidation of
LDL (14).
Furthermore, the active compounds in garlic, such as allicin
and S-allyl cysteine, possess anti-atherosclerosis
properties, thereby preventing the progression of
atherosclerosis (15).
Other
studies have shown that garlic, owing to its high content of
potent sulfuric products, is effective in protecting against
thrombosis (14, 15). Garlic does this by preventing
thrombocyte aggregation (14, 15).
Other than
preventing thrombocyte aggregation, garlic also helps to
curb other risk factors by increasing microcirculation,
decreasing plasma viscosity, and by reducing diastolic blood
pressure (16,
17).
Studies
also indicate that garlic is effective in reducing the
levels of homocysteine, an amino acid which when in excess
leads to strokes, heart disease, and heart attacks (16).
Moreover,
one study showed that long-term garlic consumption was
effective in protecting against aortic stiffness, a risk
factor for cardiovascular complications, in the elderly (18).
The
phosphorous contained in the garlic is also effective in
reducing blood pressure in communities and people that are
at a high risk of developing atherosclerosis (19).
Garlic also
contains copper, which studies show can help in the
regulation of blood pressure, thereby preventing
hypertension and other CVD risk factors (20).
One animal
study showed that a deficiency in copper results in
hypercholesterolemia, which is a significant risk factor for
cardiovascular diseases such as atherosclerosis (21).
Ascorbic
acid is also found in garlic and several studies have
intimated that the acid can help prevent atherosclerosis by
preventing oxidative stress and lipid peroxidation (22).
Bottom Line:
Garlic, owing to its several nutrients, has the capability
of lowering blood pressure and cholesterol levels, both of
which are high risk factors for cardiovascular diseases.
3. Garlic
can help enhance the immune function
One study
effectively proved that garlic helps stimulate and
strengthen the immune system by encouraging the activation
of macrophages, killer cells, T and B cells (10).
The same
study also demonstrated that garlic was effective in
protecting the body against infections of the upper
respiratory tract.
One large
volunteer study showed that garlic helped in reducing common
cold occurrences, as well as a reduced duration suffering
from a common cold episode (23).
Another
study demonstrated that supplementation of the diet with
garlic could help improve the function of the immune cells
by reducing the severity of the cold and the flu (24).
Studies
also show that germanium, a constituent of garlic, is
effective in stimulating the immune system (25).
One study
also showed that selenium, another compound found in garlic,
was useful in improving immune function in healthy patients
(26).
The same
study showed that subjects who took dietary selenium had a
lower susceptibility to viral diseases.
Studies
indicate that deficiency in the trace element, selenium, can
result in impaired immune functions (27).
Garlic
contains thiamine, and scientists now know that a deficiency
in the vitamin is the leading cause of sepsis in patients
who are critically ill (28).
Researchers
also concur that thiamine is essential in the activation of
the immune system (28,
29).
One study
showed that vitamin B1 and B6, when combined with other
essential nutrients, could help improve the immune function
of individuals suffering from end stage renal disease (4).
Garlic also
contains vitamin C (ascorbic acid), and it has long been
suggested that the vitamin is able to prevent and cure the
common cold (22).
Some
studies also indicate that ascorbic acid is capable of
activating the immune system by promoting the spread of
T-cells during an infection (22).
Bottom Line:
Garlic, through its sulphuric, fatty acid, and metal
nutrients, can help improve the immune functions in humans.
4. Garlic
contains anti-cancer properties
Animal and
human studies have conclusively shown that garlic has the
ability to suppress the development of tumors in the liver,
breasts, stomach, lungs, esophagus, skin, prostate, colon,
and bladder (30,
31,
33,
34,
35)
One study
conducted in China showed that garlic was effective in
reducing the risk of prostate cancer in men (36).
The study
showed that the effect of garlic on prostate tumors was less
potent in men with advanced prostate cancer, compared to
those who have a localized type of the cancer.
One animal
study conducted on the mammalian glands of the subjects
demonstrated that garlic helped inhibit the progression of
cancer in these glands by preventing the carcinogens from
binding onto the DNA of the glands (37).
Other
studies have found that garlic, through one of its active
compounds, diallyl sulfide, is effective in preventing
esophageal /gastrointestinal cancer (38,
39).
The
compound inhibits tumor formation, as well as the metabolism
of the cancer causing substance.
Another
study found that allicin inhibited the spread of human
colon, endometrial, and mammary cancer cells by nearly 50% (40).
Scientists
believe that garlic helps in the fight against cancer by
scavenging free radicals, repairing damaged DNA, stimulating
the activities of essential enzymes such as catalase,
increasing the levels of glutathione, and preventing
chromosome damage (41,
42).
Furthermore, garlic contains selenium, which has
demonstrated the ability to destroy the genes that are
involved in carcinogenesis (43).
Another
study showed that aged garlic extracts helped in protecting
against intestinal damage caused by methotrexate during
chemotherapy (44).
Studies
indicate that selenium, also found in garlic, can help
reduce the occurrence of cancer as well as cancer death (45).
Specifically, selenium has shown strong action against the
risk of developing colon, lung, prostate, and liver cancers,
as well as reducing the mortality from these cancers (45).
Vitamin C
is also known to possess anticancer activities by stopping
the free radicals before they can form the tumors or cause
damage to DNA (22).
Studies
also indicate that low intake of vitamin C or a deficiency
of the same can lead to an increased risk of cervical cancer
(22).
Bottom Line:
Garlic has potent anti-cancer properties against the major
types of cancers that afflict human beings.
5. Garlic
can help in the prevention and treatment of diabetes
mellitus
One animal
study found that garlic compounds such as OSC and allicin
were effective in lowering blood sugar levels in subjects
suffering from chemically induced chronic hyperglycemia (46).
Studies
also indicate that garlic is effective in improvement of
microcirculation (16), whose damage results in the more
advanced complications witnessed in patients with diabetes (47).
One
promising animal study has shown that garlic ethanol extract
can assist in reducing the blood sugar levels in mice
suffering from chemically-induced diabetes (48).
The same
study showed that the garlic extract was effective in
reversing hyperglycemia.
Another
study demonstrated that aged garlic extract was effective in
preventing stress induced hyperglycemia, a high risk factor
for the development of diabetes mellitus (49).
One human
study showed that garlic powder reduced blood glucose
concentration as well as increased microcirculation in the
skin, thereby helping in bringing diabetes under control (50).
A group of
scientists also found that a combination of garlic and
standard anti-diabetic treatments helped enhance glycemic
control in patients with type II diabetes (51).
Research
indicates that calcium, found in significant amounts in
garlic, can help prevent and manage the insulin resistance
syndrome, which often precedes the development of diabetes
mellitus (52).
Thiamine,
another constituent of garlic, can help prevent the
progression of diabetes mellitus by blocking the harmful
pathways created by hyperglycemia (53).
Bottom Line:
Garlic has been shown to be effective in the prevention and
the management of diabetes mellitus owing to its
hypoglycemic action.
6. Garlic
contains anti-microbial properties
Several
studies indicate that garlic extracts are effective against
a number of protozoa including
E. histolytica, Leishmania,
B. entozoon, O. ranarum, Crithidia, Candida albicans,
Crithidia and Leptomonas
(15,
54).
Researchers
have also found that diluted crude garlic demonstrated
anti-parasitic effects against
Hymenolepis nana as well
as giardiasis (15, 54).
Scientists
have also found that garlic extracts are useful in the
treatment of Cryptosporidiosis, a disease caused by a
protozoan parasite known as
Cryptosporidium (55).
This is believed to be the parasite that causes diarrhea in
individuals with HIV.
Other
studies have shown that garlic was an effective
antibacterial agent against common bacteria such as
S.aureus, Salmonella, E.coli,
Micrococcus, Proteus, B. subtilis, and
mycobacterium (15, 54).
One study
also demonstrated that different garlic compounds were
effective in preventing and reducing
H. pylori , a bacterial
infection that causes duodenal and gastric ulcers (56).
Another
study showed that garlic oil and powder were effective in
protecting against human enteric bacteria (57).
A group of
scientists also discovered that allicin, an active compound
in garlic, showed antibacterial activity against antibiotic
resistant bacteria (15,
58).
Researchers
have also shown that garlic extract is effective in the
treatment of S. aureus
and E.coli, making it a
potent antibiotic (59).
One study
found that garlic extract showed antiviral activity against
the human cytomegalovirus (15,
60).
Another
study showed that garlic was also effective in the treatment
and eradication of influenza B, Coxsackie virus and herpes
simplex virus (15, 54,
61).
Studies
have also indicated that garlic compounds possess antiviral
activity against human rhinovirus type 2, vaccinia virus,
and the vesicular stomatitis virus (15,
62).
When it
comes to the human immunodeficiency virus (HIV), studies
have conclusively shown that garlic compounds such as ajoene,
allyl alcohol, and the diallyl disulfide, are effective in
combating HIV infections in cells(15, 54,
63,
64).
Selenium, a
key constituent of garlic, has been shown to stop the
progression of HIV to AIDS, as well as inhibiting the spread
of other viral infections (65).
Research
also indicates that garlic extracts are effective in
combating common fungal infections (15) that include Candida
albicans, Aspergillus, Botrytis cinerea, Trichoderma
harzianum, and denture stomatitis among others (54,
66,
67,
68,
69).
Bottom Line:
Scientists have shown that garlic is an effective
anti-microbial owing to its anti-protozoal, anti-fungal,
antibacterial, and antiviral properties.
7. Garlic
can help protect against hepatotoxicity and is an effective
detoxifier
Studies
show that garlic is effective in protecting the liver cells
from chemically induced hepatotoxicity (15). For instance,
research shows that garlic can help prevent
acetaminophen-induced hepatotoxicity (15).
Studies
also show that garlic is effective in protecting against
gentamicin induced hepatotoxicity (15, 16,
70).
Furthermore, research has shown that garlic is also useful
in the prevention of nitrate induced hepatotoxicity (15,
71).
Animal
studies have also shown that garlic can help reverse the
oxidation damage caused by nicotine toxicity (16).
Researchers
have found that garlic is more effective in treating
non-severe occupational lead poisoning than penicillamine, a
chemical treatment given to individuals suffering from lead
poisoning (72).
One study
also discovered that garlic extract was efficient in
treating carbon tetrachloride induced liver fibrosis (73).
Another
study also showed that extracts from garlic protected the
liver from NDEA-induced hepatotoxicity (74).
In
addition, scientists have found that garlic was effective in
protecting the liver against ethanol-induced injuries (75).
Garlic also
contains phosphorous, one of the key electrolytes that the
kidney needs in order to balance the levels of fat, sodium,
water, and uric acid (76).
Any amounts found in excess are removed through urine.
Bottom Line:
Garlic is an efficient anti-hepatotoxic as well as
detoxifying agent. It can help prevent and treat
hepatotoxicity caused by carbon tetrachloride, nitrates,
lead, nicotine, gentamicin, and acetaminophen.
8. Garlic
can help improve the health of bones
A group of
researchers conducted animal studies on female rats and
found that garlic oil extract promoted the transference of
calcium from the intestines to the bones, thereby helping to
strengthen the skeletal muscles of the rats (77).
In
addition, the same study showed that the garlic oil was
effective in improving bone mineral content as well as the
tensile strength of the bones (77).
The
researchers also demonstrated that garlic oil could help
inhibit bone mineral loss caused by ovarian hormone
deficiency (77).
A group of
scientists found that eating garlic could help prevent hip
osteoarthritis because of the action of diallyl sulphide (78).
Another
animal study showed that the germanium contained in garlic
was effective in restoring bone strength and bone mass in
subjects suffering from osteoporosis (79).
Garlic also
contains a significant amount of calcium, whose deficiency
can result in significant loss in bone mass, as well as
rickets in children (80).
Calcium
supplementation has also resulted in lower bone mass loss in
postmenopausal women (80).
Phosphorous
is also a part of garlic, and the element is essential in
improving bone mineral content, bone mineral density, and a
reduced risk of osteoporosis in female teenagers and adults
over the age of twenty (81).
Scientists
have also noticed that an increase in phosphorous intake is
associated with an increase in calcium intake, which helps
to further strengthen and protect bones (81).
Copper,
also found in garlic is important for healthy bones.
Scientists have found that a copper deficiency is closely
linked with the mineralization of bones, and osteoporosis
(20).
Studies
also show that a deficiency in vitamin C, another nutrient
found in garlic, can lead to loss of bone mass and the
development of osteoporosis (82,
83, 84).
Bottom Line:
Garlic contains nutrients that are essential for optimum
bone health, and their deficiencies can result in bone
diseases such as osteoporosis.
9. Garlic
is rich in antioxidants
One study
demonstrated that the bioactive compounds in garlic helped
inhibit the production of free radicals in the brain and the
rest of the body (85).
Another
study found that different compounds in the garlic have
different antioxidant properties (86).
Alliin and
allicin are capable of scavenging superoxide, while the
allyl disulfide, alliin, and allyl cysteine, were capable of
scavenging the free hydroxyl radicals.
Studies
have shown that allyl disulfide is capable of reducing the
oxidative stress that testosterone can cause, as well as
accelerate the breakdown of testosterone (42).
Another
study demonstrated that germanium, one of the trace elements
found in garlic, is an active antioxidant (87).
Studies
also indicate that a deficiency in thiamine, one of the
vitamins found in garlics, results in an increase in
oxidative stress (28, 88).
Selenium, a
trace element found in garlic, is another antioxidant, and
it helps to fight against oxidative stress and DNA damage
and mutation (27, 89).
Copper, a
widely known and respected antioxidant, is also found in
abundant amounts in garlic, helping in the prevention of
oxidative damage (20).
Bottom Line:
Garlic contains a host of nutrients that possess
anti-oxidant capabilities, which help prevent, reduce, and
reverse oxidative damage in the body.
10. Garlic
can help improve cognitive function
An animal
study showed that the active compounds in garlic such as
allicin were responsible for improving brain function and
short-term memory in subjects suffering from chronic
hyperglycemia (46).
Another
animal study showed that fresh garlic helped improve memory
retention and cognitive performance in rats (90).
The researchers opined that this was because garlic had the
ability to improve the levels of serotonin in the brain.
Studies
have also shown that by reducing oxidative damage, and high
levels of cholesterol and homocysteine, garlic can help in
the prevention of dementia (91).
In
addition, research has shown that garlic is helpful in
preventing cognitive decline by protecting brain neurons
from toxicity and death (16).
Another
study demonstrated that garlic could help in the prevention
of Alzheimer’s disease by scavenging free radicals and
preventing neuronal death (92).
A study
also found that vitamin B1, also found in garlic, was
effective in improving brain function, especially short term
memory in young children (93).
Studies
have also shown that a vitamin B1 deficiency can lead to the
development and progression brain diseases such as
Alzheimer’s disease (88).
Garlic also
contains phosphorous and calcium, both of which are
essential in maintaining healthy cognitive function in
elderly individuals (94).
Bottom Line:
Scientists have demonstrated that garlic and its compounds
are essential in the maintenance of healthy cognitive
function, and the prevention of age related cognitive
diseases such as Alzheimer’s and dementia.
11. Garlic
can help improve skin health
One study
showed that water extracts from garlic were effective in
healing warts and corns when applied topically (16,
95).
Calcium, a
significant constituent of garlic, also has an essential
role to play when it comes to skin health. It is responsible
for the differentiation and reproduction of the skin (96).
Another
study theorized that calcium, in the form of nanoparticles,
could actually help hasten the process of wound healing on
the skin (97).
Furthermore, studies show that calcium is essential in
promoting the function of the skin barrier, as well as
regulating the structure of the upper layer of the skin (98).
Studies
also show that selenium, vitamin C, and copper, all of which
are found in favorable amounts in garlic, are important in
maintaining healthy skin owing to their antioxidant status
(99).
Research
has shown that vitamin C is essential in the process of
wound healing because it is responsible for the fusion of
collagen, which is especially important in individuals who
have undergone surgery (22).
Bottom Line:
Garlic contains vitamin C, copper, selenium, and calcium,
which are essential in promoting healthy skin.
12. Garlic
can be used in fighting obesity
Garlic
contains calcium, and research shows that calcium is
effective in enhancing weight regulation, thereby preventing
obesity/weight gain (100).
Researchers
have also discovered that a high dietary calcium intake is
related to a lower risk for obesity and weight gain (52).
Studies
also show that majority of obese people suffer from a
thiamine deficiency, and that dietary intake of the vitamin
from foods such as garlic can help effectively manage
obesity (101).
Bottom Line:
Garlic contains thiamine, and calcium, which studies show
are effective in promoting weight loss especially in obese
individuals.
13. Garlic
can help protect against premenstrual syndrome
Due to its
significantly high content of calcium, garlic can help in
fighting the symptoms of premenstrual depression such as
mood swings, and dizziness as well as the psychological
symptoms (102,
103, 104).
Another
study found that an increase in calcium intake helps reduce
fatigue, depression, and appetite changes in women suffering
from PMS (103,
105).
Garlic also
contains relative amounts of vitamin B1, which scientists
concur is effective in reducing the physical symptoms of PMS
(104).
Studies
also show that a deficiency in selenium, a trace element in
garlic, can lead to adverse mood swings especially in women
who suffer from PMS (89).
Scientists
have also long theorized that a deficiency in vitamin B6,
one of the vitamins in garlic, promotes severe PMS (106,
107).
Research
has shown that women with PMS that are treated with vitamin
B6 (pyridoxine) show a significant improvement especially
when it comes to emotional symptoms (108).
Studies
also indicate that ascorbic acid (vitamin C), another
constituent of garlic, can help women manage the PMS
symptoms owing to its ability to metabolize essential fatty
acids (108).
Bottom Line:
Garlic has been known to be effective in reducing the
physical and emotional disturbances that occur during PMS in
women.
14. Garlic
can help promote a healthy alkaline pH Level
Calcium, a
mineral found in abundance in garlic, helps promote an
alkaline environment, which in turn helps reduce back pain,
improve growth, as well as enhance the effectiveness of
chemotherapy treatments (109).
Phosphorous, in the form of phospholipids, helps balance the
pH levels of the body by preventing excess levels of either
alkaline or acidic compounds (109).
Bottom Line:
The calcium and phosphorous contained in garlic can help the
body achieve a healthy pH level, which is crucial in the
prevention of diseases.
15. Garlic
can help promote eye health
Due to its
significant amount of thiamine, garlic is a good candidate
for promoting eye health. One study showed that thiamine
treatment can help reverse vision loss especially in
alcoholism cases (110).
Studies
also show that an increase in thiamine intake in individuals
suffering from alcoholism can help heal the alcohol-damaged
nerves responsible for eye movement (111).
Scientific
research also shows that thiamine is associated with a lower
risk of developing open-angle glaucoma, which is one of the
leading causes of permanent blindness (112).
Scientists
have also theorized that thiamine, along with other vitamin
B compounds, can help deter the development of cataracts
(113).
Bottom Line:
Garlic, owing to its significant levels of vitamin B1, is
essential in promoting proper eye health.
