Here is the translation of the provided content into English: For the past month, my son sometimes gets muscle cramps in his feet and doesn't digest food well.

Patient's question:

For one month, my son sometimes gets muscle cramps in his feet and has poor digestion. He is currently drinking HiPP formula.

Doctor's answer:

It may be caused by a lack of calcium. There are two ways to supplement calcium: calcium supplements and dietary calcium. The most common and traditional calcium-rich foods are dairy products, which are not only rich in calcium but also easy to absorb. Examples include oysters, nori, cabbage, cauliflower, Chinese cabbage, daikon radish, kale, and pak choi.