"All things are poison, and nothing is without poison; only the dose permits something not to be poisonous." --Paracelsus[1]

Most people are familiar with the idea that anything can be poisonous if the dose is large enough. The median lethal dose of water is >90 ml per kg[2]. This means that a 150 lb person has the potential to die if they consume more than 6.1 liters of water without eliminating any of it. High estimates for the capacity of the human stomach are 2-4 liters[3], making the median lethal dose difficult to reach. This article is not about consuming garlic until you croak (which could take nearly 58 grams of garlic oil for a 150 lb person, provided humans react in the same way that mice do[4]). No one would accidentally consume that much garlic, but what about smaller doses? Is the amount of garlic used in your dinner going to help you or hurt you?

Garlic is your friend.

Wild Garlic FlowerCredit:

Garlic boosts your immune system. Several components of garlic, namely the sulfur-based allicin, which is antibacterial and anti-fungal, and the element selenium, have been shown to support the network of organs and cells that work to protect your body from infection. Garlic is often prescribed by naturopathic physicians as a treatment for colds[5][7], either brewed in tea with honey (antibacterial) and lemon juice (antiseptic) or diced up and swallowed like pills.

Garlic has also been shown in animal and human studies (randomized, double blind, placebo-controlled--the good kind) to reduce serum lipid, specifically LDL, triglyceride levels, and atherosclerosis (artery hardening)[6]. The reduction in atherosclerosis is attributed to LDL cholesterol becoming resistant to oxidation in the presence of garlic. Further studies also showed that treatment with garlic lowered blood pressure and blood glucose levels[6].

Garlic is your foe.

High dose toxicity has been demonstrated in rats and mice. Lower (but still high) and consistent consumption of raw garlic by rats caused breakdown of red blood cells which led to anemia, weight loss, and inhibition of growth. Further studies showed stomach injury, liver inflammation, and a decrease in sperm production when rats were fed garlic oil or powdered garlic. However, only reports of discomfort (nausea, bloating, dizziness, upset stomach, allergic reactions) were seen in human studies, with the exception of one dangerous side effect, which was only seen when combined with anticoagulants[6].

But, what about smaller doses? Evidence from biofeedback studies done by James Hardt[8] show that consumption of garlic (and onions, which contain similar compounds) decreases your brain's ability to produce alpha waves, as shown on an EEG (though you can increase your ability to produce alpha waves through meditation and training). Alpha waves are associated with increased creativity, lowered anxiety, and peak performance or being "in the zone"[9].

EEG Cap for measuring brain wavesCredit:

Many eastern traditions, such as Taoists and Hindus, emphasize that garlic should only be used for medical purposes. Taoists believe that consumption of garlic fouls your Chi. Yogis are forbidden from consuming garlic and onions due to their detrimental mental and spiritual effects (which likely refers to the effect that garlic consumption has on alpha waves)[11]. There have even been reports that pilots are asked to not consume garlic 72 hours before completing a test flight. In The Better Baby Book: How to Have a Healthier, Smarter, Happier Baby[10], Lana and Dave Asprey recommend avoiding garlic and onion consumption in order to maximize the health, happiness, and intelligence of your baby.

So, should I eat it or not?

Yes...or no. There are many compelling reasons to consume garlic. The successful medicinal uses of garlic have been reported throughout history and are currently reported in reputable medical journals. It makes your food taste great! It will protect you against vampires! (okay, maybe not.)

But what about the detrimental effects? Try doing a "garlic detox": remove garlic from your diet for a week and compare the way you feel and perform mentally to how you felt prior to the detox. If you feel better, use that to guide your normal consumption. If you feel the same as you did before, try a longer detox or just resume your normal consumption.

Now Foods Super Odorless Garlic Capsules, 90-Count
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(price as of Jul 1, 2014)