Author: Fan Zhihong
Associate Professor, Department of Nutrition and Food Safety, College of Food Science, China Agricultural University, Ph.D. in Food Science
Director of Chinese Nutrition Society, senior member of China Food Science and Technology Association, director of Beijing Popular Science Writers Association and other positions.
The main teaching and research directions are the impact of cooking and processing on the nutritional and health value of food, the design and development of nutritious food and nutritional recipes, and the impact of health factors on food selection, etc., and he is the chief editor and co-editor of 11 textbooks and published 116 papers.
Source: Fan Zhihong – Original nutritional information
It has been authorized to be reprinted by China Clinical Nutrition Network
How much milk is good to drink per day? Do middle-aged and elderly people want to eat dairy products every day?
Some people think that it should be eaten because it is beneficial to supplement calcium and increase protein supply.
But some people think that there is no need to eat, because some studies have shown that calcium supplementation is not good for preventing osteoporosis
[1]
。
Some people have also seen literature reports that eating more dairy products is prone to fractures
[2]
。 I even heard scientific news that more calcium supplementation can cause heart disease
[3]
Wait a minute.
(Image source: WeChat public platform public photo library)
These words sound very confusing, but the truth is not so subversive. First, because of different eating habits, the epidemiological survey data done in the United States and Europe may not be applicable in China; Secondly, the amount of "eating more" mentioned in foreign research and the "eating more" we think is likely to be far from the same.
For example, the research news of "more calcium supplementation doubles the risk of cardiovascular disease" says: compared with people with daily calcium intake between 600~1000 mg, calcium intake of 1400 mg, all-cause mortality increases by 40%, the risk of cardiovascular disease death increases by 49%, and the risk of ischemic heart disease increases by 114%.
If dietary intake of calcium is greater than 1400 mg per day, supplemented with calcium tablets above 500 mg, the risk of all-cause mortality is increased by 157% [3].
Sounds scary. But if you think about it, in fact, this danger has nothing to do with the vast majority of Chinese people.
Chinese average dietary calcium intake is only about 400 mg per day. Even if you drink an extra 1 pound of milk (about 500 mg of calcium), or take calcium tablets containing 500 mg of calcium, it is only more than 900 mg. It is also within the reasonable range (600~1000 mg) mentioned in the study, far from the amount of 1400 mg that is harmful to the heart.
Pooled analysis found that the relationship between calcium intake and cardiovascular disease death was a U-shaped curve. Too much is not good, too little is not good [4]. When you consume 800 mg of calcium from food per day, you have the lowest risk of death from cardiovascular disease (this is the recommended amount of calcium intake in China!). ）。 The risk of death was significantly increased below 500 mg compared with 800 mg intake, but there was no additional benefit above 900 mg, and a modest increase in the risk of death if continued to 1400 mg.
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Similarly, even drinking 1 pound of milk a day only adds 15 grams of protein (calculated at 3% protein content).
According to the recommendations of the dietary guidelines, about 50 grams of chicken (10 grams of protein), 1 egg (6 grams), and 50 grams of fish (8 grams) per day can supply 24 grams of protein, plus 1 kilogram of milk of 15 grams, a total of 39 grams, animal protein intake can not promote calcium loss.
What's more, most Chinese people can't even drink half a kilogram of milk every day.
Most of the studies that say that dairy products are not useful for osteoporosis prevention have been done in European and American countries with high calcium intake. Discussions sometimes add a sentence: if dietary calcium intake is really low, it is not necessarily this result.
The so-called lack of what to supplement, in European and American countries, calcium intake is not a shortage of dietary nutrition, no matter how much you eat, it may be useless. In contrast, supplementing with vegetables, fruits, legumes, and increasing your intake of potassium, magnesium, and vitamin K may be more helpful for bone health. However, for Chinese, calcium has always been a nutritional shortcoming for most people.
In addition, for the elderly, eating enough protein is also important to maintain muscle. When the muscles decay, people are more likely to fall and fracture. Countless studies have suggested that whey protein in milk is good for maintaining muscle, and casein is also helpful.
A recent study of nutritional interventions[5] published in BMJ found that it is better to eat enough calcium and protein, at least for the elderly. (Friends who don't want to see the details of the research can turn to the end of the article to see the suggestions)
The researchers divided the average age of 86 years into two groups, one was a control group and the other was a nutritional intervention group. The so-called nutritional intervention is to change the subject's food, or supplement a certain nutrient.
Testing was conducted at the beginning of the study, and both groups of elderly people did not have vitamin D deficiency. However, the protein intake of the elderly is a bit less. The daily intake of calcium is 700 mg (still more than the average intake in China of 400 mg), and the protein intake is 58 grams.
Compared with the control group, the elderly in the nutrition intervention group added half a kilogram of milk per day, plus 20 grams of cheese or 100 grams of yogurt. In this way, their daily calcium intake increases to 1142 mg and protein intake to 69 grams.
Two years later, comparing the risk of falls, fractures, and hip fractures between the two groups, it was found that the group with increased calcium and protein intake performed significantly better: a slight increase in bone density, an 11% reduction in the risk of falls, a 33% reduction in fracture risk, and a 46% reduction in the risk of hip fracture.
(Image source: WeChat public platform public photo library)
For the elderly, it is good to appropriately increase milk food, so if you eat a lot of dairy products from a young age, will it increase the risk of cardiovascular disease? There isn't much data at the moment, but a recent study[6] suggests that it won't.
In this study, Finnish researchers began to track 1029 children and adolescents aged 3~18 years since 1980 and investigated their dietary conditions many times. These respondents had high and low calcium intake in childhood and adolescence, averaging more than 1,000 mg per day, and as well as adulthood, averaging more than 1,100 mg. However, there are large differences between people, from the standard deviation, there are less than 800 mg and more than 1400 mg. The main source of calcium is dairy products. However, it is unlikely to be as low as the Chinese average.
In 2001, 2007 and 2011, adult respondents were examined carefully to measure important data related to cardiovascular disease risk, including blood pressure, high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), triglycerides (TG), carotid medial thickness, arterial pulse wave velocity (PWV), carotid compliance (CAC), Young's modulus of elasticity (YEM), and vascular stiffness index (SI).
Data analysis showed that after eliminating the influence of other interfering factors, no long-term consumption of calcium exceeding the recommended amount was found to be associated with risk factors for cardiovascular disease. In other words, from childhood to adulthood, in the past two or three decades, calcium (dairy products) eat more than 1400 mg, which does not bring about the deterioration of cardiovascular health indicators.
Of course, because these children are not old enough, they are only 34~49 years old, and it is impossible to determine what will happen to them when they reach old age.
According to the current research information, my understanding of milk calcium supplementation is as follows:
1. By increasing a glass of milk (or yogurt, milk powder, etc. with corresponding calcium content) per day, the daily calcium intake reaches 800 mg, which not only increases the supply of protein, calcium, vitamin B1, B2, B6, vitamin A and vitamin K, but also benefits cardiovascular health.
2. The elderly should pay special attention to ensuring calcium and protein intake. Whether it's milk, yogurt, or cheese, eating a little dairy every day is good for maintaining muscle health and helping to prevent falls and fractures.
3. If you have problems such as acute or chronic allergy to milk, drinking milk is easy to acne, or have other adverse reactions, then you need to avoid dairy products, but add other foods such as soy products (dried tofu, water tofu, tofu thousand zhang, etc.), low oxalic acid green leafy vegetables (such as Chinese cabbage, small rape, kale, etc.), small fish and shrimp to supplement calcium.
4. If you are prone to gas and diarrhea after drinking milk, you can choose yogurt. Yogurt is easy to digest and absorb, and the utilization rate of calcium is also very high (lactic acid is conducive to mineral absorption and utilization). Among yogurts, it is recommended to choose varieties that are not too high in sugar (less than 12 grams of carbohydrates in 100 grams, or less). People with lean indigestion can also choose cheese instead of milk.
5. If you really don't like the taste of milk and feel that yogurt is too cold in winter, consider mixing milk/powder/cheese with other foods.
(Image source: WeChat public platform public photo library)
Recommended eating method 1: Add milk to various noodle foods, and use milk instead of water to knead the dough, delicious and nutritious.
Recommended way to eat 2: Add milk or milk powder to hot rice porridge, hot oatmeal, hot mash soup, and hot corn paste to strengthen breakfast nutrition.
Recommended Eating Method 3: Add milk to hot black tea or hot coffee and drink it as a delicious drink.
Recommended eating method 4: Add cheese to the main foods such as bread, steamed bun slices, and cakes. If your breakfast is not greasy, there are no fritters and the like, and there is no fatty bun pie, then adding 20 grams of cheese to breakfast will not cause obesity.
Recommended way to eat 5: Steam custard with skim milk instead of water, the taste will not change significantly, but there will be more calcium and protein.
As long as you really want to get the nutrients in it, you can always find a delicious and convenient way to eat!
Bibliography:
1 Bolland MJ, Leung W, Tai V, et al. Calcium intake and risk of fracture: systematic review. BMJ 2015; 351:h4580
2 Michaëlsson K, Wolk A, Langenskiöld S, et al. Milk intake and risk of mortality and fractures in women and men: cohort studies. BMJ 2014; 349:g6015
3 Michaëlsson K, Melhus H, Lemming EW, et al. Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study. BMJ, 2013, 346:f228
4 Wang X, Chen H, Ouyang Y, et al. Dietary calcium intake and mortality risk from cardiovascular disease and all causes: a meta-analysis of prospective cohort studies. BMC Med, 2014, 12: 158
5 Iuliano S, Poon S, Robbins J, et al. Effect of dietary sources of calcium and protein on hip fractures and falls in older adults in residential care: cluster randomised controlled trial. BMJ，2021，375:n2364
6 Wu FT, Pahkala K, Juonala M, et al. Childhood and long-term dietary calcium intake and adult cardiovascular risk in a population with high calcium intake. Clinical Nutrition，2021, 40(4):1926-1931
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