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In 2000, FAO proposed that June 1 day be designated as "World Milk Day" every year. Promote the nutritional value of milk and its importance to human health. For a long time, dairy products have been advertised as rich in calcium and protein, which helps children grow and strengthen their bones. But are dairy products really good for health? Let's see what the review in the New England Journal of Medicine says.
Dairy products such as milk, yogurt and cheese are good sources of calcium, which helps to maintain bone density and reduce the risk of fracture. The Reference Intake of Dietary Nutrients for China Residents (20 13) recommended that the daily calcium intake of adults over 8 years old should be1000 mg; Calcium 1200mg is needed every day in the second trimester, the third trimester and the lactating mother. A cup of milk (200 ml) contains 200~350 mg of calcium (depending on the brand and the type of milk), and contains (or adds extra) vitamin D, which helps to maintain bone quality.
Dairy products are a good source of protein, which helps to maintain the growth of normal tissues and cells and prevent muscle loss in the elderly. The Reference Intake of Dietary Nutrients for China Residents (20 13) recommends that men above 18 should take 65g in protein and 55g in protein every day. A glass of milk (200ml) contains about 6.6g of protein.
But the sources of calcium, protein and vitamin D in dairy products can also be obtained from other foods. For example, if you eat 100g of Chinese cabbage, you can consume 1 17mg of calcium and 1.4g of protein. Eating an egg can get 6.9 grams of protein and 29.6 milligrams of calcium. Other food sources, such as kale, cauliflower, tofu, nuts, various meats, etc.
Research published in the New England Journal of Medicine shows that it may not be necessary to increase the intake of dairy products. The best intake of dairy products depends on the overall diet quality: if the diet quality is low, especially for children from low-income families, eating dairy products can improve the nutritional status; However, if the diet is of high quality, increasing the intake of dairy products is unlikely to bring substantial benefits and may also cause harm.
Milk contains a lot of branched-chain amino acids (leucine, isoleucine and valine), which is the key to the quality of protein (protein's amino acid score). These amino acids will increase the concentration of insulin-like growth factor I(IGF-I) in human blood, thus mediating the role of growth hormone and promoting growth. Leucine can specifically activate the target of rapamycin target protein (mTOR) pathway, thus promoting cell replication and inhibiting cell apoptosis. Promoting the influence of human height on health is complicated. Being tall is associated with a lower risk of cardiovascular disease, but with a higher risk of many cancers, hip fractures and pulmonary embolism.
Blood pressure, blood lipid and cardiovascular diseases
The content of potassium in milk is relatively high, and the content of sodium is relatively low, suggesting that increasing milk intake can lower blood pressure, but the specific mechanism is still unclear. Moreover, randomized trials show that the results of lowering blood pressure are inconsistent, and both whole milk and low-fat milk have no obvious relationship with the incidence or mortality of coronary heart disease or stroke. Because if milk is used instead of sugary drinks or other refined carbohydrates in the experiment, the result may be beneficial; But if milk is used instead of nuts, beans or whole fruit, the result may be different.
Some studies think that there is a cross reaction between milk protein and islet cells, so it may be considered as the cause of 1 diabetes, but the relationship between them is still unclear. Cohort studies show that dairy intake is related to a moderate reduction in the risk of type 2 diabetes; Studies have also proved that eating more milk (lactose tolerance) has nothing to do with the risk of diabetes. Moreover, people who drink milk have a lower risk of diabetes than those who eat sugary drinks or fruit juice, but people who drink milk have a higher risk of diabetes than those who drink coffee.
Previous studies have shown that the intake of dairy products is closely related to the incidence of breast cancer, prostate cancer and other cancers. The effect of milk intake on plasma IGF-I may increase the risk of prostate cancer, and the risk correlation is the highest. In addition, the total intake of dairy products is related to the increased risk of endometrial cancer, especially for postmenopausal women who have not received hormone therapy, which may be related to the content of sex hormones in dairy products.
However, some studies have shown that eating milk may be inversely proportional to the risk of colorectal cancer, which may be due to high calcium content. However, almost all the studies in the existing literature are carried out in middle-aged or above people, and many cancer risk factors play a role in childhood or early adulthood. In addition, in a study on teenagers' diet, it was found that milk intake may not be related to the increased risk of breast cancer in the future.
Allergy and intolerance
About 4% babies are allergic to milk protein, which leads to quite a few nutritional problems. It is reported that the intake of milk may make babies more susceptible to asthma, eczema and food allergies. Randomized controlled studies show that infants who are randomly assigned to receive hydrolyzed protein formula have lower risk of any allergic diseases and eczema than infants who receive milk. There are also studies that show that children eat soy milk and their symptoms will be alleviated.
Total mortality rate
Generally speaking, the relationship between milk intake (total fat, high fat and low fat) or total intake of dairy products and total mortality is still inconclusive. But dairy products are better than processed red meat or sugary drinks, but not as good as plant proteins such as nuts. At the same time, it has not been proved that low-fat dairy products are obviously superior to full-fat dairy products.
Macronutrients and micronutrients contained in milk can promote human health, but these nutrients can be obtained from other foods. For adults, the general evidence does not support that eating a lot of dairy products can reduce fractures. In addition, the total intake of dairy products has no significant relationship with weight control/risk of diabetes and cardiovascular disease. Eating a lot of dairy products may increase the risk of prostate cancer and endometrial cancer, but it will reduce the risk of colorectal cancer. At present, researchers suggest that the intake of dairy products should be combined with the actual nutritional status, and there is no need to deliberately increase it.
Note: This article aims to introduce the progress of medical health research, and does not recommend treatment schemes. Please go to a regular hospital for treatment plan guidance.
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