When the elderly buy milk, they do not necessarily choose high-calcium milk.

　　“Is “high calcium milk” worthy of its popularity?
　　
　　We did a test on the milk in the supermarket. They bought a variety of boxed milk from three brands on the market and measured the nutritional content using standard methods. The protein content was in line with the label, or even slightly higher. According to national standards, the protein content should be greater than or equal to 2.9%, while the actual measured data is 3.0% to 3.1%. The same goes for fat, which is slightly higher than the labeled value.
　　
　　The key issue is calcium content. The calcium content of ordinary milk per 100 grams is between 102 and 107 mg, but what about high-calcium milk? Between 109 and 112 mg. On the packaging, it is clearly written that the calcium content reaches 130 to 140 mg, and some even claim to be no less than 150 mg.
　　
　　Originally, adding a large amount of calcium to milk was a very technically difficult matter, as there was a delicate balance between protein and calcium. If the calcium content is artificially increased, it is easy to cause instability in the protein system.
　　
　　That is to say, if residents buy real "high calcium milk" and take it home, if it is heated before drinking, the protein in it will easily react and form a certain white precipitate, and the taste will not be as fresh and sweet as ordinary milk. The "high calcium milk" available on the market tastes basically the same as ordinary milk after heating.
　　
　　Many consumers have a misunderstanding, thinking that only foods with extra calcium can supplement calcium. Merchants also take advantage of consumers' ignorance of the natural and efficient calcium supplementation of certain foods and deliberately label some foods as "high in calcium." As for the effectiveness of calcium supplementation, there is still no scientific data to prove it.
　　
　　Based on this reasoning, if calcium is added to food production, it can be called high-calcium food. Then should gypsum tofu and brine tofu all be renamed as "high-calcium tofu" or "high-calcium and high-magnesium tofu"?
　　
　　The top priority for consumers is to understand what natural calcium-supplementing foods are, to supplement calcium for the body scientifically and rationally, and not to blindly pursue the "high calcium" label. Dairy products and soy products are the most efficient calcium supplement foods.