Many cardiovascular patients are used to asking what they should eat when they are discharged from the hospital, and I think the answer will be “low salt diet”. So today we will share with you the story of salt and health. How harmful is too much salt? The China Burden of Disease Study shows that in 2013, deaths caused by a high-salt diet accounted for 12.6% of all deaths in China, with up to 25.2% of deaths due to cardiovascular disease attributable to a high-salt diet. So why does a high-salt diet increase deaths? It is mainly related to the excessive intake of sodium in a high-salt diet. Moderate sodium intake helps maintain osmotic pressure and acid-base balance in the body. But when there is too much sodium in the body, it can cause water and sodium retention, leading to increased blood volume and blood pressure, and high blood pressure can further lead to cardiovascular events such as strokes and coronary heart disease. Secondly, some studies have shown that too much sodium can also increase urinary calcium excretion and increase the risk of osteoporosis. Finally the high osmotic pressure of a high salt diet can directly affect the gastric mucosa and increase the risk of cancer. How much salt is healthy to eat per day? China’s dietary guidelines recommend that daily salt intake should not exceed 6g, but in fact, China’s per capita daily cooking salt intake is much higher than this: a survey in 2012 showed that it can be as high as 10.5g. Therefore, there is still much room for you to reduce your daily salt intake. In addition to table salt, how much “invisible salt” do you eat? To reduce salt intake, we need to understand the sources of salt. The intake of salt in daily life does not only come from the direct addition of salt in cooking, but also from some “invisible salt” that we can easily ignore. For example, a bucket of instant noodles can contain up to 5.5 g of salt, which is close to the upper limit of daily salt intake. Table 1 shows the sodium content in some of our daily foods. Table 1: Sodium content in selected foods How can I measure how much salt I eat? There are many ways to measure salt intake, but the 24-hour urine sodium test with repeated measurements is currently considered the most accurate method because most of the body’s metabolism of sodium is excreted in urine and the amount excreted is proportional to the amount consumed, but it is difficult to implement because it is time-consuming, laborious and has low compliance. Secondly, a point-in-time urine sodium test can also be used instead of the 24-hour urine sodium test method, and a certain formula can be used for conversion estimation, but the applicability of this conversion relationship in different populations has not yet been universally accepted. Various dietary survey methods can also be used to assess population salt intake, such as the weighing method, 24-hour dietary review method, and food frequency method, but dietary survey methods generally underestimate salt intake. Table 2: Advantages and disadvantages of different salt intake assessment methods How to reduce salt intake? Given that the sources of salt are cooking salt and extra cooking salt, we can reduce salt intake mainly from these two aspects. Cooking salt 1. Reduce the frequency of eating out; 2. Reduce condiments with high sodium content, including MSG and soy sauce; 3. Try not to drink vegetable soup; 4. Use a quantitative salt spoon when cooking as much as possible to serve as a warning, Figure 1. Cooking salt 1. Avoid or reduce processed foods with high sodium content, such as pickled vegetables, ham, and pickled products; 2. Get into the habit of browsing the nutrient composition table of processed foods to understand the salt content of ingested Food salt content. Is low sodium salt better? There are many types of salt in supermarkets, and the more popular one in recent years is low-sodium salt. Is this low-sodium salt a hype concept or is it really useful? The so-called low sodium salt is edible salt made from one or several kinds of refined salt, crushed washing salt, sun salt, etc., and processed with food additives (such as potassium chloride, etc.) allowed by the state in order to reduce the sodium ion concentration. It is true that clinical studies have shown that low sodium salt can significantly reduce blood pressure levels compared to regular salt. However, the increased potassium content of low sodium salt may lead to hyperkalemia in people with renal failure or those on potassium-protective diuretics (e.g. spironolactone) with long-term use. In conclusion, salt plays an essential role in our life activities and daily life as a necessary dietary condiment, but excessive long-term intake can be harmful, so we need to develop good dietary habits and reduce salt intake appropriately.