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JUICING A POUND of kale for your daily breakfast may not be a good idea. Kale and other cruciferous vegetables (broccoli, brussel sprouts, cabbage, bok choy, turnips, arucola) when eaten raw in very large amounts can interfere with thyroid functioning and, in the worst case, lead to an enlarged thyroid, called a goiter. To decrease the risks, cook your cruciferae, or vary your greens with non-cruciferous veggies like cucumbers, tomoatoes, zucchini and carrots.
Spinach, too, can interfere with thyroid function. Also it contains purine, a substance occurring in most living cells, which in excess can lead to the accumulation of uric acid, causing gout and kidney stones. To benefit from spinach’s healthy vitamins, it must be ingested with a “good fat” such as olive oil – along with jokes about how Popeye really did need Olive Oyl…
For both spinach and kale, only organic veggies avoid the pesticides that can accumulate excessively on dark leafy vegetables.
To digest asparagus, because humans do not have the right enzymes to break down its complex carbohydrates, bacteria in the intestines must ferment the stalks – leading to the formation of gases that must then be released from the body. For most people, asparagusic acid is excreted in urine, causing the characteristic odor of “asparagus pee” and changing its color. But for some people who have not inherited the right enzyme for doing this, eating too many asparagus at once can cause severe pain and digestive problems.
–Mary Carpenter