Folic acid must be it. Yogurt doesn't give me this reaction, but greek yogurt and kefir do. And I like both far far more than yogurt. And it's so so healthy. All in due time, I guess.

38 yo@dx, female, non-smoker, non-drinker, SCC right lateral tongue. T2N2aMx stage IVa; 1/20/09 bilateral neck dissection, hemiglossectomy, micromets in 2 right nodes, left all clear. 33xIMRT + 3 cisplatins. Tx completed 5/08/09. PET scan 7/29/09 clear, 5/26/10 clear, chest x-ray 5/23/11 clear