According to this website (http://naturealmom.com/preventing-treating-recurrent-plugged-ducts/), here are some food and supplements you can try:
B-complex vitamins, vitamin C, evening primrose oil, thyme, probiotics and consuming 3-4 raw garlic cloves (try taking with orange juice) have been known to help plugged ducts.
Also, try eating wholesome, nutritious foods, and reduce your intake of saturated fats, drink plenty of water.
Soy Lecithin supplement is also one very popular solution that worked for many. You can purchase it at most pharmacies in Singapore. It is also available on iHerb:
http://sg.iherb.com/Lecithin#p=1
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