Firstly, one of the most prominent members of the Allium family: garlic to the rescue (again)!
Research has shown that garlic possesses wonderful anti-microbial and anti-inflammatory qualities that could persist throughout the digestive tract (1) and even substantially reduce levels of H Pylori (2). However, garlic also contains large amounts of inulin (a fiber than can be broken down by beneficial bacteria in the gut), therefore it can actually stimulate the growth of more desirable probiotic bacteria while killing off more pathogenic (disease causing) species (3). As far as dosage is concerned... you can have too much of a good thing: raw garlic on an empty stomach is a powerful emetic. Play it safe and enjoy with food in small quantities (less than 2 raw cloves per meal).
Disclaimer: a garlic clove is not an entire bulb. Please don't eat two bulbs of raw garlic. I once had a seminar attendee get these terms confused. He went home at ate two "cloves" of garlic... For the remainder of the series no one was sitting within a six foot radius of this poor guy :)
1) Mol Nutr Food Res. 2015 Mar;59(3):434-42.
2) Avicenna J Phytomed. 2016 Sep-Oct;6(5):495-501.
3) Int J Food Sci Nutr. 2009 Dec;60(8):717-27.
Interested in this kind of information? Watch for the release of our new series "The Gut/ Brain Connection & Beyond!"