Rumor: Some milk advertisements claim to contain immunoglobulins that can boost immunity against the new coronavirus.

Scientific interpretation:

Some milk advertisements claim to contain immunoglobulins, which can enhance the body's immunity against the new coronavirus. Is there really immunoglobulin in milk? Is it useful in fighting the new coronavirus?

First of all, milk may contain immunoglobulins.

Immunoglobulins are a class of immune proteins that bind specifically to antigens, and most have antibody activity. These include the five major classes of immunoglobulin A (IgA), immunoglobulin D (IgD), immunoglobulin G (IgG), immunoglobulin E (IgE), and immunoglobulin M (IgM).

The main bovine immunoglobulins contained in milk are in the IgG category. These are produced in the cow's mother's body and then delivered to the calf's mouth, where they are incorporated into the body to form the calf's immunity while the baby's intestinal tract is not yet developed enough to absorb the larger molecules of protein.

But pay attention to these three points:

1, immunoglobulin is afraid of heat, more than fifty or sixty degrees Celsius may be gradually inactivated

Refrigerated pasteurized milk is usually heated for a short period of time at 70-90 degrees Celsius, which has already inactivated part of the immunoglobulin. The immunoglobulin thing is even less of an issue with sterilized milk that has a shelf life of six months to a year at room temperature and is heated to more than 120 degrees Celsius.

So, only those milks that are processed with low temperature sterilization can maximize the immunoglobulin activity.

2. Antibodies in milk only work in the human gut and do not enter the bloodstream

When we drink milk, the protease enzymes in our intestines gradually break it down into small peptides and individual amino acids before it is absorbed into the bloodstream. By this time, the pieces of immunoglobulin have long since lost their biological activity. And, because bovine immunoglobulin is not the same as human immunoglobulin and is a 'foreign protein', if bovine protein does enter the human bloodstream, our immune system will automatically attack it, triggering an allergic reaction.

Cattle antibodies only work in the human gut. And since human diseases and bovine diseases don't exactly coincide, bovine antibodies don't completely solve all kinds of gastrointestinal disease problems when they pass through the human gut, but they may help some. For example, by immunizing cows, antibodies to certain intestinal pathogens are produced. When humans drink these low-temperature processed milk, the immunoglobulin "through the intestine" can destroy some intestinal pathogens, so that the human body to reduce the chance of bacterial food poisoning.

3, antibodies can not be mixed

First of all, the cow mother of what pathogenic bacteria produced antibodies, may be able to pass these antibodies to their own baby cows. And to produce immunoglobulins such as antibodies, you need to be exposed to the appropriate antigen first, such as a certain bacteria, or a certain virus. The antigenic stimulation also has to be repeated many times if you want the antibody production to be higher. In the end, even if the antibodies are present in the cow mom's blood, only a fraction of them may make it into the milk.

If the cow mom hasn't been exposed to the new coronavirus and defeated it, then she won't be able to produce that antibody and pass it on to her baby cow through her milk either. So far, no milk on the market dares to claim that it contains antibodies to the new coronavirus.

So while some milk products contain immunoglobulins, these are not the same as proteins that are relevant to boosting immunity to the New Coronavirus and therefore cannot be claimed to be beneficial in preventing viral infections.

To add to this, human breast milk has the same mechanism as cow's milk. A breastfeeding mom can pass on antibodies her body possesses to her baby through her milk, extending protection for her infant beyond the womb. If the mom has recovered from C.N.C.P., and the viral tests have been confirmed negative, then she can breastfeed her baby. This does not rule out the possibility that the mom may be able to pass antibodies to her baby in this way. But whether it contains antibodies to the new coronavirus, and whether the antibodies are potent enough, there are no research data to confirm.

How do I drink milk?

The main benefit of fresh milk is not so much the small amount of cow immunoglobulin, but more about improving the overall dietary nutritional balance. For example, for people with nutritional deficiencies, the high-quality proteins, B vitamins and vitamin A in milk can help maintain the body's own immunoglobulin production.

So if you're not afraid of a little more expensive milk on a daily basis, it's perfectly fine to choose milk that is of better quality and retains more of its active ingredients. If you're just afraid of the new coronavirus and want your body to be more resistant to disease, then you don't have to stick to drinking a certain kind of milk, eat three meals, improve the overall nutritional balance of your diet, get a good night's sleep, exercise moderately, and stay in a good mood, which is probably more important.

Discrediting expert: Fan Zhihong, director of the China Nutrition Association and associate professor at the School of Food at China Agricultural University