Many of garlic's healthy properties derive from sulfur-containing compounds; garlic is typically deficient in American diets. Red blood cells produce hydrogen sulfide (H2S) from garlic sulfides which dilates blood vessels and helps control blood sugar(1); garlic has general cardioprotective attributes(1,2). It "contains a compound called diallyl trisulfide (DATS) that is an effective therapeutic agent in preventing tumor progression"(2); diallyl sulfides increase protein ferroportin, a bridge allowing iron stored in cells to exit and move on to more needed bodily locales. "[D]iallyl sulfide (DAS) and thiacremonone in garlic have been shown to have anti-arthritic properties"; the herb is anti-inflammatory and reduces the inflammatory formation of fat cells. Note: sulfur compounds in garlic get their activity inhibit if garlic cooks for over 5-15 minutes(1).
Garlic also contains "vitamin C, vitamin B6, selenium, and manganese" and the latter two both function in antioxidant protection systems of the body. Having garlic at least several times weekly has been shown to lower risk of colorectal and renal cancer and more daily consumption all but prostate and breast cancers(1). Selenium and Vitamin C present are beneficial for eye health and with eye infections. Placing 2 crushed garlic cloves on an infected wound provides rapid relief(2). Further note: bad breath and abdominal pain indicate that garlic is working. "Odorless" garlic has vastly reduced allicin, the key antibiotic and otherwise health compound(1).
Sources:
1. 7549wpczar. "Garlic." TruthWiki: Get the Real Story, TruthWiki, Get the Real Story. 6 years ago. Web. 3 June 2020. http://www.truthwiki.org/garlic/.
2. Nagdeve, Meenakshi. "14 Powerful Benefits Of Raw Garlic." Organic Facts: Let's Get Healthy Together, Organic Information Services, Pvt Ltd. Updated 21 May 2020. Web. 3 June 2020. https://www.organicfacts.net/health-benefits/herbs-and-spices/health-benefits-of-garlic.html.