Hello, Your question: Why should flaxseed cause/increase acne?
Lignans are antiparasitic and are beneficial for inflamation.
Lignans not only have anti-cancer properties, they also have anti-viral, anti-bacterial, and anti-fungal properties. They are also a potent anti-oxidant.
I had a severe case of rosacea. I know that the medical community states that the cause for rosacea is unknown and that there is no cure. My dermatologist told me this very thing. That was not acceptable to me. I started researching it. Unfortunately, there was not much written on it at the time of my research. Fast forward...In my experience it is due to a fungal overgrowth in the body. A body that is very toxic and in need of cleansing. . The facial skin of a person with rosacea is usually home to demodex mites. These mites cause inflammation.
To get back to your question. If you feed your body something that fights parasites, parasites being an organism that feeds and lives on another organism, (that would include candida, fungus, and ...) that host, the parasite, living off the waste of your body is going to fight back. This is why your rosacea Acne worsened. You are trying to kill your host and they don't like it!
Should you consume flax seed oil? I would consume the oil and the ground seed daily. I mix my oil in organic cottage cheese or goat yogurt and then I sprinkle ground flax seed on top. Like the Johanna Budwig diet. It is very healing for the body. Omega Nutrition is a very good brand. I use Barlean's organic.
Flax seed/oil is used in the treatment of many diseases and it is great for the skin and hair. It is also one of the oils I use when oil pulling. However, it will not cure your rosacea.