Why is eating too salty bad for our health?

Studies have shown that excessive salt intake is harmful to people’s health, which can lead to high blood pressure and increase the risk of heart disease and stroke. The global salt reduction programme is gaining new momentum, whether through awareness-raising activities or through government intervention.

The same is true of South Africa. Three years ago, China became the first country to implement mandatory salt indicators for staple foods such as bread and soup. This is in line with the World Health Organization (WHO) proposal to reduce salt intake by 30% by 2025. South Africa will soon further reduce its sodium target. The approach taken in South Africa is to target the involuntary intake of salt – salt has been added to food. Their view is that this will be the most cost-effective way to prevent high blood pressure – high blood pressure is the main cause of heart disease and stroke.

The study estimates that approximately 23,000 cardiovascular diseases and 5,600 deaths in South Africa can be prevented each year by reducing salt intake. The new law to reduce salt intake can save the United States $51.25 million in health care costs for cardiovascular disease. It is still too early to say whether the new law has the expected effect on health – it will take several years to achieve. But this policy does play a role in reducing the salt content of staple foods such as bread.

As part of a WHO study on global aging, researchers tested salt intake in South Africans before the new law was implemented, and the work is now being repeated to determine if salt intake is decreasing. South Africa has also made concerted efforts to raise public awareness of excess salt intake and cardiovascular health.

Studies have shown that this is significant in changing people’s behavior, such as adding salt to food during cooking and eating. But in the medium to long term, will these interventions produce government-predicted health outcomes? Key indicators will be to lower blood pressure and reduce cardiovascular events such as heart disease and stroke. Part of the reason is that the government is adjusting policies based on new scientific discoveries about how salt affects the body. This is a frontier area that scientists around the world are exploring.

Researchers have challenged some of the assumptions about how salt affects the body for decades. Their findings — and the findings of other international researchers — suggest that the mechanisms involved in salt and cardiovascular health may be more complex than originally thought. This in turn indicates that there is a lot of room for adjustment in terms of improving the prevention and treatment of common diseases such as hypertension. For example, the researchers emphasize that reducing salt intake can significantly reduce the deleterious effects of hormones associated with high salt intake. Blood pressure, heart structure and blood vessels are all affected. This further demonstrates the importance of policies that target salt intake.

What do we know now?

Over the years, there has been a number of convincing evidence that high salt intake is closely related to cardiovascular events such as hypertension and heart disease. But emerging research has begun to question the physiological mechanisms of the link between salt intake and elevated blood pressure. A common consensus in medical textbooks for decades is that high salt intake can lead to thirst. Therefore, higher water intake leads to an increase in blood volume, which leads to an increase in blood pressure, and eventually water and salt are excreted by the kidneys and blood pressure.

But German researcher Jens Titze recently discovered that salt is stored in the skin. The researchers further showed that high salt intake is accompanied by minimal water loss. These surprising discoveries have been skeptical by the global health science community, but they also emphasize the need for scientists to conduct more in-depth research on blood pressure mechanisms.

American researchers Alexei Bagrov and Olga Fedorova have identified another factor in how salt affects cardiovascular health. Marinobufagenin is a steroid hormone whose properties are similar to those found in Bufo marinus toad venom. The function of this hormone is to maintain the balance of the salt, so the body will produce this substance when it is ingested in large quantities. However, as a response to excessive salt intake, high levels of this steroid hormone cause elevated blood pressure, affecting the heart structure and increasing the stiffness of the animal’s blood vessel wall.

Researchers have recently started their first tests on healthy young people, and for the first time they have confirmed a strong positive correlation between increased salt intake and increased steroids. The researchers found that large intakes of salt were associated with aortic stiffness, even in very young people. The researchers then tested whether this was due to the steroid hormone or the salt itself. When they analyzed the data of these two substances, they found that the culprit was steroid hormones, not necessarily salt. This steroid hormone is not only associated with aortic stiffness, but also associated with elevated blood pressure and increased left ventricular mass.

Healthy young adults consume an average of 11.8 grams of salt per day (more than two teaspoons). The World Health Organization recommends taking less than 5 grams (one teaspoon) of salt per day. Conclusions The latest findings suggest that South Africa should reduce salt in staple foods to further reduce daily salt intake. The evidence also strongly supports the continuation of public awareness campaigns to reduce excess salt intake and protect cardiovascular health.