Nine rumors and truths about calcium loss

Author: Fan Zhihong, Associate Professor, Department of Nutrition and Food Safety, College of Food Science, China Agricultural University, PhD in Food Science, Director of Chinese Nutrition Society, Director of China Health Education and Promotion Association
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Chinese people’s dietary calcium intake is generally insufficient, and this problem is often overlooked
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Although long-term calcium deficiency will not cause obvious symptoms of discomfort, it will affect the quality of life of a person—for example, it affects the height and body shape formed in adolescence, affects the risk of osteoporosis in middle-aged and elderly, and affects mood.
The stability of blood pressure affects the risk of insomnia.
A diet with more sodium and less calcium also increases the risk of adults suffering from hypertension, stroke and obesity
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In addition to insufficient intake, there are many factors that affect calcium utilization and calcium retention
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What makes the calcium in our bones sneak away, and what makes the calcium eaten in foods not fully function? Are many claims about "calcium loss" circulating on the Internet really reliable? Here are a few common rumors for everyone
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Rumor 1: Eating more salt will cause calcium loss? Really .
Sodium intake has a great relationship with urine calcium excretion, and the conclusion of this study has not changed over the years .
Every 2300 milligrams of sodium (equivalent to 6 grams of salt) removed by the kidneys will also lose 40 to 60 milligrams of calcium .
If a middle-aged woman eats 1,000 milligrams of sodium (equivalent to 2.
5g of table salt) a day and needs to be excreted, but does not take in too much calcium, all the excreted calcium comes from bone calcium, then 1% more bone calcium will be lost every year .
Some studies on high blood pressure also suggest that high sodium intake is not only a factor in raising blood pressure, but also a factor in promoting calcium loss in the body and increasing the risk of kidney stones . 　　　　　　Considering that the salt intake of Chinese residents (average more than 9 g/day) far exceeds the recommended value of the World Health Organization (5 g/day), some areas in the north are even as high as 12~18 g/day, and calcium intake The amount (close to 400 mg) is only half of the recommended value (800 mg).
The bone calcium loss caused by excessive sodium intake cannot be ignored.
The so-called "eating less salt = more calcium supplementation" is by no means a false statement
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Myth 2: Soy products are better for bone health than meat? 　Really .
When evaluating the contribution of food protein to calcium supplementation, the indicator "calcium/protein" may be used .
For Chinese people who consume low dairy products, soy products are an important source of calcium in the diet .
Although meat foods are rich in protein, the calcium content is generally very low.
For example, beef contains only 23mg/100g of calcium, and pork is 6mg/100g .
Soybeans, the raw material in soybean products, contain up to 191mg/100g of calcium.
After making tofu, brine or gypsum must be added to increase the content of calcium and magnesium .
For example, the calcium content of brine tofu is 138mg/100g, and the calcium content of gypsum tofu is 116mg/100g, which is much higher than that of meat products .
Moreover, the magnesium, vitamin K and soy isoflavones contained in soybeans can effectively increase the utilization rate of calcium, thereby reducing the risk of calcium loss .
Rumor 3: The more dairy products you eat, the more calcium deficiency is? Fake .
Comparing the research results of China and the West, it can be found that although there is no clear correlation between the intake of dairy products and bone density in Western countries where the basic calcium intake is already high, it is based on the actual situation in China.
According to research evidence among Chinese people, increasing calcium from dairy products is beneficial to improving bone health .
Chinese people’s dietary calcium intake is relatively low.
Among the various factors of bone development, calcium intake is often a “short board”. 　　　　　　　.
Therefore, if the high-efficiency use of milk calcium can be increased, the intake of dairy products will be increased from 0 to 250 grams per day (calculated by milk), which will not increase the intake of protein and saturated fatty acids excessively, and will improve the people’s health.
Peak bone density is beneficial and harmless
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The claim that the protein in dairy products promotes calcium loss and makes the calcium in dairy foods unavailable has also been denied by the research institute
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Myth 4: Vegetarian food will definitely reduce calcium loss? 　Fake .
Studies have found that eating a vegetarian diet does not mean that the urine calcium loss must be lower than that of meat eaters, because if vegetarians eat refined grains, the calcium content is very small, and insufficient potassium and magnesium intake will also reduce the use of food calcium.
Rate .
At the same time, if vegetarians do not pay attention to nutritional balance, insufficient supply of high-quality protein, few outdoor activities and not paying attention to vitamin D supplementation, it will reduce the bioavailability of calcium .
Some human studies have found that the urinary calcium loss of vegan dieters is not lower than that of meat-eating omnivores .
Myth 5: Eating fruits can reduce calcium loss? 　　Really .
Epidemiological studies have shown that people with more fruits in their diet have higher bone density at the same calorie and protein intake, and the risk of fractures in adolescents is also reduced .
Researchers believe that it may be because fruits are rich in potassium, which helps reduce urinary calcium excretion, and vitamin C in fruits is also one of the factors that promote calcium absorption .
Of course, to say that eating more fruits is beneficial is that without reducing the intake of soy products, dairy products and green leafy vegetables, fruits themselves contain less calcium and cannot be used to replace these main food sources of calcium .
Rumor 6: Green leafy vegetables help reduce calcium loss? 　Really .
Green leafy vegetables are not only rich in calcium, but the nutrients such as magnesium, potassium, vitamin K and vitamin C are all factors that increase the utilization of calcium.
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Although oxalic acid is generally contained in vegetables, fruits, nuts and beans, most of the oxalic acid can be removed by blanching green leafy vegetables.
In addition to spinach, leeks, amaranth, apricot, radish, etc.
, Chinese cabbage, milk cabbage, rape, etc.
The oxalic acid content of common dark green vegetables such as cabbage sprouts, chicken hair greens, Chinese kale, mustard greens, chrysanthemum chrysanthemum, broccoli, lettuce leaves, and lettuce is very low and can basically be ignored
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　Rumor 7: Eating more whole grains will cause calcium loss? 　Fake .
There are rumors that the phytic acid in whole grains can be combined with calcium, resulting in a decrease in the utilization rate of calcium and the loss of calcium in the food .
In fact, the calcium content of whole grains is higher than that of white rice noodles, and the content of potassium and magnesium is much higher than that of white rice, which helps to increase the utilization rate of calcium .
For example, the potassium and magnesium contents of ordinary indica rice (long grain rice) are 107 and 28mg/100g, while the potassium and magnesium contents of unmilled black indica rice are 256 and 147mg/100g, respectively .
The potassium and magnesium content of millet is 284 and 107mg/100g respectively, which is also much higher than that of polished rice .
Therefore, although the phytic acid in whole grains has the effect of reducing the utilization of calcium, the calcium content and potassium and magnesium content are more, which are enough to make up for the loss caused by phytic acid .
In fact, there is no research evidence that the introduction of half of whole grains in the staple food will increase the risk of osteoporosis .
　Rumor 8: Drinking coffee will make people lose osteoporosis? Fake .
Coffee made from coffee beans is not only a good source of potassium, but also a source of oxalic acid and caffeine .
Potassium helps reduce calcium loss, while oxalic acid reduces calcium absorption rate, and caffeine increases urine calcium loss .
Caffeine only has a short-term diuretic effect.
In the case of drinking a small amount of coffee, it will not cause a significant increase in the daily calcium loss in urine .
On average, the caffeine in each cup of coffee will only increase the loss of calcium by 2 to 3 mg　　　　　.
If you add pure milk when drinking coffee, the calcium obtained from the milk can be used to make up for the loss of calcium caused by caffeine and oxalic acid
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The survey also found no evidence that people who drink two cups of coffee a day are more likely to suffer from osteoporosis or fractures than those who do not drink coffee.
Therefore, it is currently believed that drinking coffee in moderation will not harm bone health
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　　Rumor 9: Being jealous will cause bone calcium to dissolve and lose? 　　Fake
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There may be two sources of this rumor: one is the residual poison of the term "acidic physique", which believes that all acidic foods are not good for health; the other is that vinegar can dissolve calcium carbonate precipitation, and it is believed that vinegar will also dissolve bone calcium.

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In fact, vinegar can help people with low stomach acid to turn insoluble calcium in food into an ionized state, which is conducive to calcium absorption
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At the same time, the aged vinegar that has been brewed after aging contains high calcium (according to the data in the food composition table, 125mg/100g, comparable to milk)
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After vinegar is absorbed into the blood, it will be oxidized into carbon dioxide and water, and it is impossible to "dissolve bones" and then be directly excreted in the urine
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Studies have also found that replacing chloride ions with acetate and bicarbonate in the diet can significantly reduce the loss of urinary calcium
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In other words, eating less salt and more vinegar is beneficial to increase the utilization rate of calcium
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