Garlic: The bulb that brightens health

By Liz Meszaros, MDLinx
Published April 19, 2019

Key Takeaways

Since the beginning of man’s recorded history—and perhaps even earlier—garlic has been revered for its medicinal properties. In fact, garlic (Allium sativum)—which is related to onions, leeks, scallions, chives, and shallots—may be one of the earliest examples of man using plants to treat diseases and stay healthy.

This lowly bulb has been found in the Egyptian pyramids and ancient Greek temples. It has been referenced in the Bible, and in ancient medical texts from Egypt, Rome, China, and Greece. Garlic was even prescribed by Hippocrates for several conditions, and was given to the original Olympic athletes in Greece to enhance their physical performance.

Garlic is very nutritious and has few calories. A 1-oz (28 g) serving contains 23% of the recommended dietary allowance (RDA) of manganese, 17% RDA of vitamin B6, 15% RDA of vitamin C, 6% RDA of selenium, and 0.6 g of fiber. Garlic also contains calcium, iron, vitamin B1, copper, potassium, and phosphorus. All this for only 42 calories and 9 g of carbohydrates.

When garlic is crushed, chopped, or chewed, sulfuric compounds are formed. These include—but are not limited to—allicin, which is present only briefly in fresh garlic, diallyl disulfide, and S-allyl cysteine.

Only recently has science seemingly caught up with what the ancients seemed to have known long ago—that garlic really is good for you! Let’s take a look at some of its clinically proven benefits.

Boosts immune function, and fights the common cold. In one study, researchers found that taking a daily garlic supplement for 12 weeks actually reduced the incidence of colds by 63% compared with placebo, and study participants who took the supplement recovered 70% faster when they caught a cold (1.5 days vs 5 days, respectively).

In another study, researchers found that high doses (2.56 g/d) of aged garlic extract reduced the number of days subjects were sick with a cold or the flu by a full 61%.

Improves blood pressure in high doses. In numerous studies, investigators have found that aged garlic supplements can reduce blood pressure levels in hypertensive patients, but the dosage must be fairly high—equivalent to approximately four cloves of garlic per day.

Researchers also found that aged garlic extract (600–1,500 mg/d) was as effective as atenolol, a beta blocker, at lowering blood pressure over 24 weeks.

Improves cholesterol, lowering the risk of heart disease. Garlic can lower total and LDL cholesterol levels by approximately 10% to 15%, and possibly raise HDL levels, according to severalmeta-analyses and studies.

Contains antioxidants to fight oxidative damage. Antioxidants protect us against the cellular damage and aging that is inherent to the human condition. Garlic supplements—in high doses—can increase antioxidant enzymes and reduce oxidative stress. These antioxidant properties, coupled with garlic’s cholesterol and blood pressure reducing abilities, may lower risks of developing neurological diseases such as dementia and Alzheimer’s disease.

Lowers the risks of some cancers. Researchers have documented the benefits of garlic in several cancers:

  • Lung cancer: Over a 7-year period, researchers in China observed that subjects who ate raw garlic at least 2x/week had a 44% lower risk of developing lung cancer.
  • Glioblastoma: Researchers demonstrated that three organo-sulfur compounds found in garlic (diallyl sulfide, diallyl disulfide, and diallyl trisulfide) were effective in eradicating brain cancer cells.
  • Prostate cancer: In a review of the literature on Allium vegetables (9 studies in 132,192 subjects), researchers concluded that garlic, in particular, was associated with a lower risk of developing prostate cancer.

In addition, garlic has been shown to protect against organ damage induced by heavy-metal toxicity, improve bone health, protect against alcohol-induced liver injury, and lower the risk of spontaneous premature delivery.

Garlic how-to’s

Another plus for garlic is that it is an essential part of the Mediterranean diet, which has been linked to lower risks for various chronic diseases, better quality of life, better brain health, and longevity. Garlic is easy to include in your diet. For when you do, here are some tips:

  • Pick the freshest bulbs. Make sure garlic skin is tight, and not loose, dry, or moldy. The fresher the garlic, the more concentrated the ingredients and nutrients. And although garlic can keep for months when stored properly, it’s better to eat it within a week.
  • Store it correctly. Keep garlic in a cool, dry place, with good ventilation.
  • Chop it. Just the action of chopping, slicing, or smashing garlic can trigger an enzyme reaction that increases the healthy compounds it contains. Heat curtails this, so it’s best to let garlic sit for at least 10 minutes before you cook it or add it to any dish.

Unfortunately, scientists have shown that the anti-inflammatory benefits of raw garlic are reduced by even short-term heating. Raw garlic may be best, but the side effects of that include garlic breath (for everyone) and indigestion (for some). Believe it or not, researchers studied the best way to reduce garlic breath, and concluded that eating apples, lettuce, or raw mint leaves after a meal laden with garlic will help neutralize its sulfuric compounds, which are what cause the strong odor.

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