The calcium content of animal bones is of course the highest, because the main component of bones is calcium carbonate.

Extended reading:

Can shrimp skin be fully digested with so much calcium?

In fact, there is a lot of calcium in shrimp skin, but the absorption rate is not ideal. If calcium is to be absorbed, it must be dissolved first. However, shrimp shells cannot be completely chewed by human teeth, and only a small part can be dissolved after being acted on by gastric acid in the stomach. Most of the calcium will be excreted with undigested residues. Unless it is finely crushed, the effect will be better.

However, the calcium in milk is soluble and forms a delicate complex with protein, citric acid and phosphoric acid, which does not need human body to chew at all.

There is only calcium in shrimp skin, and there is no factor to help calcium absorption. It does not contain vitamin D, so the utilization rate of calcium cannot be fully guaranteed. Milk naturally contains vitamin D, which can promote the absorption of calcium. Lactose in milk, lactic acid in yogurt and casein phosphopeptide produced by protein digestion can also promote calcium absorption. Therefore, the utilization rate of calcium in milk is the highest among all kinds of natural foods.

Therefore, the calcium content of shrimp skin is high, but the calcium supplement effect is poor.