This is a companion blog post to my video on garlic, which you can view here.
In descending order of priority, the garlic supplements that I take are:
Life Extension Optimized Garlic (for allium content).
Swanson's Odor Controlled Garlic (for SAC content).
Kyolic Aged Garlic Extract Extra Strength Reserve (for other phytochemical content).
A. In terms of phenolic content mg/Kg, onion is superior to garlic, which is slightly superior to leeks. In terms of antioxidant status as judged by the DPPH assay, onions are superior to leeks, which are superior to garlic.
B. Garlic extract releases nitric oxide from S-nitrosoglutathione (GSNO) more than onion extract which does it more than leek extract.
GARLIC (Allium sativum)
A. Garlic contains over 100 secondary bio-active metabolites broadly categorized as organosulfur compounds, carotenoids, and polyphenols.
B. Organosulfur compounds:
a. When the garlic bulb is crushed, ground, or cut, the enzyme alliinase, together with the reactive intermediaries sulfenic acids, transform the amino acid alliin into allicin. Allicin is absent in the intact garlic bulb.
i. Allicin appears to be a defensive compound for the garlic plant, as it produces pain in predators by activating the TRPA1 and TRPV1 excitatory ion channels.
b. Allicin is a sulfur-containing, volatile compound. It is the most abundant thiosulfinate in fresh garlic, accounting for 70% of total thiosulfinates and 0.4% of the mass of fresh garlic. A single clove of garlic contains about 4-5 mg of allicin.
c. Allicin is highly lipophilic, allowing it to quickly pass through cell membranes, where it reacts with free thiol groups.
d. Allicin can be transformed into lipophilic organosulfur compounds, including diallyl disulfide (DADS – 67%, at room temperature), diallyl trisulfide (DATS – 15%), diallyl sulfide (DAS – 13%), and diallyl tertasulfide (5%).
e. Allicin can be transformed into hydrophilic organosulfur compounds, including S-allyl cysteine (SAC) and S-allyl mercaptocysteine (SAMC).
i. Allicin and SAC inhibit NFkB.
f. Allyl cysteine, alliin, allicin, and allyl disulfide scavenge free radicals differentially.
g. Allicin’s shelf-life can be increased with the addition of vinegar. At a lower pH of 5-6, allicin has a half-life of 10-17 days.
a. While onion has large amounts of quercetin (1497 mg/Kg), kaempferol (832 mg/Kg), and luteolin (391 mg/Kg), garlic has myricetin (693 mg/Kg), apigenin (217 mg/Kg), and quercetin (49 mg/Kg).
D. Fatty acids:
a. 23% of the lipids in garlic are phospholipids, while 14% are glycolipids and 63% are neutral lipids.
a. Flavonoid and phenolic content varies widely between cultivars.
b. Garlic varieties that contain florets or that are grown at higher altitudes tend to have higher S-allyl-L-cysteine sulfoxide (AlCSO), and those that are grown at lower altitudes tend to have higher phenolic contents.
A. Aged garlic is manufactured by soaking garlic in 12-20% aqueous ethanol for up to 20 months at room temperature, producing an extract that is filtered and concentrated at low pressure and temperature. This process converts the pungent odor of the water and lipid-soluble organosulphur compounds. It causes a loss in allicin though it increases the activity of S-allyl cysteine (SAC), S-allyl mercaptocysteine (SAMC), allixin, selenium, and N-fructosyl arginine.
B. Compared to fresh garlic extract:
a. Note on AGEs: Chronic hyperglycaemia (due to diabetes) produces protein glycation and eventually advanced glycation endproducts (AGEs), which cause tissue damage and oxidative stress and are responsible for many of the complications of diabetes. AGEs agonize the receptor for AGEs (RAGE).
b. Aged garlic extract is about 2x more capable at inhibiting cross-linked AGEs.
c. Aged garlic is more capable at inhibiting post-Amadori AGE formation at higher doses only.
d. About a 1/3rd better at inhibiting fructosamine formation.
e. Slightly worse at inhibiting glycation-induced protein carbonyl formation but better at inhibiting glycation-induced protein thiol formation.
f. Has a 1/3rd more antioxidant power on the ABTS (TEAC) assay (19 compared micrometer to 19.5 micrometer for vitamin C) and less (about 45% less) antioxidant power on the DPPH assay.
g. Fresh garlic is better at chelating iron ions than aged garlic.
h. In terms of phenolics, aged garlic has 129 mg/g whereas fresh garlic has 56 mg/g.
i. In terms of flavonoids, aged garlic has 101 mg/g whereas fresh garlic has 47 mg/g.
j. In terms of flavonols, aged garlic has 94 mg/g whereas fresh garlic has 43 mg/g.
GARLIC & INFLAMMATION
A. Garlic extracts improve the activity of glutathione.
B. Garlic powder extract inhibits NF-kB response to lipopolysaccharides in human blood.
C. A meta-analysis of 16 trials found that garlic reduced C-reactive protein by 0.61 mg/L in 13 trials, interleukin-6 by 0.73 ng/L in 5 trials, and tumor necrosis factor alpha by 0.26 ng/L in 7 trials.
a. Another meta-analysis found a reduction of 0.8 mg/L in C-Reactive Protein across 9 trials.
b. One meal of raw crushed garlic consumed alters the expression of genes relevant to immunity, apoptosis, and xenobiotic metabolism in human blood.
D. Allicin’s anti-inflammatory potential is so great that it prevents the destruction of cartilage in rodent models of osteoarthritis.
GARLIC & METABOLISM
A. Allicin increases the expression of uncoupling protein 1 (UCP1), likely indicating that it can increase the presence of brown adipose tissue (BAT).
B. Allicin appears to improve insulin resistance, decrease adiposity, and improve glucose homeostasis in obese rodents via BAT activation.
C. Allicin attenuates weight gain in a fructose-induced rodent model of the metabolic syndrome.
GARLIC, THE LIVER, AND KIDNEYS
A. Allicin improves glutathione peroxidase, glutathione reductase, and glutathione S-transferase activity in the liver.
B. Garlic extract appears to protect the liver from acetaminophen-induced damage.
C. In rodent models, allicin protects against NAFLD via its anti-inflammatory and antioxidant effects.
D. Allicin appears to protect kidneys from toxins in a similar manner.
GARLIC & DIABETES
A. Allicin appears to inhibit the activity of anti-islet antibodies present in type 1 diabetes.
GARLIC & CANCER
A. Epidemiological data indicates that allium vegetable intake, particularly intake of garlic and, to a lesser degree, onions, is inversely associated with gastric cancer incidence/mortality.
B. Epidemiological data also indicates that allium vegetable intake is inversely associated with prostate cancer incidence.
C. Allicin induces apoptosis in hepatocellular carcinoma cells.
D. Allicin induces apoptosis in glioma and glioblastoma cells.
E. Allicin inhibits telomerase and induces apoptosis in gastric cancer cells.
F. Allicin induces apoptosis in colon cancer cells (via Nrf2).
GARLIC & CARDIOVASCULAR HEALTH
A. It is thought that garlic’s cardio-protection is mediated by allicin and other organosulfur metabolites interacting with thiol groups and thiol-containing compounds (e.g. glutathione) to produce free hydrogen sulfide, which interacts with nitric oxide.
B. Garlic inhibits platelet aggregation by increasing cyclic nucleotides and by inhibiting fibrinogen binding and thus inhibiting platelet shape change.
C. A meta-analysis of 20 trials showed that garlic lowered systolic blood pressure by 5.1 mm Hg and lowered diastolic blood pressure by 2.5 mm Hg. This reduction appears to be evident only in hypertensive people.
D. A meta-analysis of 39 trials found garlic to reduce total cholesterol by 17 mg/dL and LDL-C by 9 mg/dL in people with total cholesterol of over 200 mg/dL, after a minimum of two months of use. This finding is less consistent than that on blood pressure.
E. Allicin prevents oxidized LDL from producing endothelial cell injuries by inhibiting apoptosis and oxidative stress.
F. Allicin inhibits cholesterol synthesis in the liver, while other metabolites also act on the synthesis differentially.
G. Allicin may be protective against atherosclerosis because of its inhibitory effect on TMAO synthesis.
GARLIC & THE BRAIN
A. Allicin may be neuroprotective from glutamate excitotoxicity. It has been shown to potently inhibit glutamate release in rodents’ brains.
B. Allicin is neuroprotective from traumatic brain injury. It exerts this neuroprotective effect by inhibiting oxidative damage and neuronal inflammation via increasing the phosphorylation of Akt and nitric oxide synthase.
C. Allicin is neuroprotective from ischemia-reperfusion (the return of blood supply following a hypoxic state) injury by inhibiting oxidative stress, inflammation, dysfunction of the mitochondrial respiratory chain, and apoptosis while upregulating antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase, and glutathione S-transferase.
D. Allicin dose-dependently inhibits both acetylcholinesterase and butyrylcholinesterase, thereby increasing the activity of acetylcholine in the brain.
E. In a rodent model of Alzheimer’s disease, allicin improves cognition by reducing oxidative stress, mitochondrial dysfunction, and reducing beta amyloid expression.
F. In a rodent model of cognitive impairment, allicin improves cognition by upregulating the Nrf2 antioxidant pathway.
G. In a rodent model of social defeat stress-induced depression, allicin attenuated depressive symptoms by reducing microglia activation, reducing inflammatory cytokine expression, reducing abnormal iron accumulation, and limiting neuronal apoptosis in the hippocampus.
GARLIC & HEAVY METAL POISONING
A. Allicin can potently and dose-dependently reduce the retention of lead (e.g. by up to 74% in the liver) in tissues and blood, though it also reduces zinc in tissues.
B. Garlic extract can also reduce retention of cadmium.
C. Allicin protects the liver from iron-induced damage.
D. Garlic extract protects against the cytotoxicity due to mercury poisoning.
E. Allicin protects the liver from damage due to arsenic poisoning.
GARLIC & THE MICROBIOME
A. Garlic exhibits antibacterial effects on gram-positive and gram-negative bacteria, as well as an ability to sensitive bacteria to antibiotics. It also exhibits anti-parasitic and anti-fungal effects. The chemical mechanism by which it exerts its antimicrobial effect remains unclear.
a. Inorganic polysulfides derived of organosulfur compounds are even more potent.
B. Kyolic aged garlic extract was found to increase the species of Lactobacillus and Clostridia after 3 months of supplementation.
C. Antimicrobial potential of garlic varies across genotypes and growing conditions.
D. Allicin reduces the transformation of L-carnitine into TMAO.
E. Allicin has proven to be useful in the treatment of Helicobacter pylori infections.
ALLICIN IN GARLIC & SUPPLEMENTS
A. Black garlic has less allicin than pickled garlic, which has less allicin than boiled garlic, which has less than roasted garlic. Enteric tablets had less bio-available allicin than non-enteric tablets, and enteric tablets were absorbed worse when consumed with a high-protein meal.
B. A study found that most garlic supplements produced less than 15% of the allicin they claimed to contain, mostly due to having low alliinase activity and not disintegrating quickly enough.
A. Note that one gram of fresh garlic should produce 1000 to 3333 mcg of allicin (1 to 3.33 mg).
a. Dried garlic should yield about 3x more allicin, since it is devoid of water.
B. Avoid: Garlique and Spring Valley (Walmart).
C. Lowest cost per mcg of allicin and potential allicin is Life Extension Optimized Garlic, which is 4.5x cheaper than the second cheapest (Nature’s Way Garlinase 5000).
D. Lowest cost per mcg of SAC is Swanson's Garlic Odor-Controlled, which is 4x cheaper than the second cheapest (Solgar Garlic Powder).
a. The cheapest aged garlic, per mcg of SAC, is Kyolic Aged Garlic Extract, which is 9x more expensive than Swanson’s.
E. ConsumerLab overall pick was Swanson's Garlic Odor-Controlled Garlic.
a. $0.07 per capsule.
b. 1 capsule provides 3060 mcg of alliin (0.61% of the powder) and 633 mcg of allicin (0.13% of the powder).
c. In total, 3 capsules a day procide 6030 mcg of allicin and 12,900 mcg of SAC.
F. However, Life Extension Optimized Garlic has far more allicin but far less SAC.
a. $0.095 per capsule.
b. Two capsules contain 57,400 mcg of alliin (4.8%) and 15,080 mcg of allicin (3.4%).
c. In total, two capsules provide 40,910 mcg of allicin and 224 mcg of SAC.
G. The top pick for aged garlic was Kyolic Aged Garlic Extract Extra Strength Reserve.
a. $0.2 per capsule.
b. In total, 2 capsules a day provide 3000 mcg of SAC (0.25%).
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