Lactose problems are a sign, to me, of low gut-flora issues, since natural Lactobacillus feed on lactose.
From my own experience, candida is a direct toxifier of the glands/adrenals/thyroid. It creates toxic acetaldehyde in the system to name one. http://www.thecandidayeastanswer.com
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Also, if you have adrenal issues, and a large percentage of the population does, vitamin C is indispensable. Use one with biofavinoids. This is a clue to why C helps with colds, since the adrenals affect immunity so drastically.