Depend, before meal with empty stomach Enzyme can cleanse your blood, after meal is to help digest so you can absorb the nutrient from your food.

根据需要不同，都可以。饭前吃，有利于清除血液毒素，饭后吃，有利于吸收营养。

youdao

After so much rich food, on the 13th day you should have simple rice congee and mustard greens (choi sum) to cleanse the system.

吃了那么多大餐之后，十三那天，人们就和稀粥吃芥菜清肠胃。

youdao

You could go with something heavy and strong like a Belgian ale to to cut through the fats and starches, something light to cleanse the palate between bites to let the food shine, or something darker, malty, and moderate to complement the traditional main dishes.

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