The Truth About Salt: More for Longevity, Less for Health? Unveiling the Complex Relationship Between Salt and Lifespan

The Truth About Salt: More for Longevity, Less for Health? Unveiling the Complex Relationship Between Salt and LifespanSalt, a vital seasoning and essential nutrient since ancient times, has always been inextricably linked to human health. However, the relationship between salt and lifespan has been a subject of controversy in the scientific community for over a century

The Truth About Salt: More for Longevity, Less for Health? Unveiling the Complex Relationship Between Salt and Lifespan

Salt, a vital seasoning and essential nutrient since ancient times, has always been inextricably linked to human health. However, the relationship between salt and lifespan has been a subject of controversy in the scientific community for over a century. The World Health Organization has stated that reducing dietary salt intake by 3 grams per day is predicted to prevent 60,000 to 120,000 new cases of COVID-19 annually, and reduce all-cause annual deaths by 40,000 to 90,000. Meanwhile, other researchers propose that increasing salt intake may extend lifespan, a notion seemingly aligned with the common saying, "Without salt, there's no energy."

Case Study: A Warning from Mr. Liu

Recently, an elderly man named Mr. Liu visited a hospital. He had always been robust, but in recent months, he had experienced fatigue, chest tightness, and palpitations, especially after consuming pickled foods. Despite repeated pleas from his children, he stubbornly clung to the belief that "without salt, there's no energy," until his symptoms became unbearable.

After a thorough examination and consultation, the doctor found that Mr. Liu's blood pressure was alarmingly high at 180/113mmHg. He denied any prior history of hypertension or heart disease, but admitted to a long-standing habit of high salt intake, particularly enjoying pickled foods. The doctor recommended blood and electrocardiogram (ECG) tests. The results showed that Mr. Liu's total serum cholesterol (TC) was as high as 7.2mmol/L, and his low-density lipoprotein cholesterol (LDL-C) reached 5.1mmol/L, far exceeding normal ranges. The ECG revealed sinus arrhythmia and mild myocardial hypertrophy, indicating abnormalities in his heart function.

To further assess his condition, the doctor arranged ultrasound scans of Mr. Liu's heart and carotid arteries. The results showed that his left ventricular diastolic function had declined, and the left carotid intima had thickened, with a carotid plaque narrowing reaching nearly 50%. The doctor warned that if treatment was delayed, the plaque could further develop and lead to serious consequences.

Based on the findings from all examinations, Mr. Liu was diagnosed with stage II hypertension (high risk), hypercholesterolemia, and carotid plaque stenosis. Faced with these diagnoses, he was bewildered, wondering how he had developed these conditions. The doctor explained that the most likely culprit was his hypertension, which was closely associated with his long-term high salt intake.

The doctor prescribed Mr. Liu medications to lower blood pressure and cholesterol, emphasizing the importance of taking them as prescribed and not adjusting the dosage without consulting him. He also advised Mr. Liu to adjust his dietary structure, strictly control salt intake, avoid pickled foods, increase fresh fruits and vegetables, and consume quality protein. The doctor encouraged him to exercise regularly, quit smoking, limit alcohol consumption, and maintain healthy lifestyle habits.

After three months of treatment and adjustments, Mr. Liu returned to the hospital for a follow-up examination. His blood pressure was within the normal range, his total serum cholesterol and LDL-C had decreased, and his initial symptoms had significantly improved. He exclaimed, "I never imagined that eating too much salt could cause so many problems! This has been an eye-opening experience!"

Mr. Liu's case is not an isolated incident. Similar cases are common in our daily lives. So, is the saying "more salt, longer life" true, or does "more salt, more harm" hold the real truth? What is the actual truth about salt and lifespan? This article will delve into this topic from multiple perspectives, helping you scientifically understand the intricate relationship between these two elements.

I. The Benefits and Drawbacks of Salt: The Health Risks Behind an Essential Nutrient

Salt, seemingly ordinary, plays a vital role in maintaining life activities. Long-term salt deficiency in the body can lead to a series of serious consequences.

1. Guardian of Cell Osmotic Pressure and Water Balance

Na in salt is an essential electrolyte in maintaining cell osmotic pressure and water balance. If we liken the body to a reservoir, cells are the small ponds within it, and Na acts as a precise regulator. By combining with water molecules in the body to form hydrated ions, Na ensures the balanced distribution of water inside and outside cells.

If long-term salt intake is inadequate, it can lead to imbalances in body fluid content, resulting in edema or dehydration. This, in turn, disrupts metabolism and affects the normal functioning of the body.

2. Power Source for Nerve Conduction and Muscle Contraction

When nerve endings are stimulated, they generate action potentials, a process that also depends on Na. Na ensures that nerve impulses are transmitted quickly and accurately to muscles, triggering muscle contractions. Everyday activities like walking, running, and more complex movements rely on the smooth functioning of this process. Long-term salt deficiency can weaken muscle contractility, leading to fatigue and weakness.

3. Maintainer of Bone Health

When Na levels in the blood are insufficient, the body draws on bone reserves to replenish them, maintaining equilibrium. This chronic depletion can lead to calcium loss from bones, increasing the risk of osteoporosis. A study on the correlation between low sodium intake and height development in young people suggests that long-term dietary sodium deficiency can lead to stunted bone development (short stature, skeletal deformities), increased fracture rates, decreased bone density, and slow growth and development in adolescents.

4. Regulator of Body Acid-Base Balance

Na works with bicarbonate ions (HCO) to regulate body acid-base balance, protecting cells from damage in acidic or alkaline environments, playing a positive role in maintaining the stability of the internal environment.

5. Promoter of Digestive Function

Na stimulates the secretion of gastric acid and digestive enzymes, aiding in the breakdown and absorption of food in the gastrointestinal tract. Long-term salt deficiency can lead to weakened digestive function, affecting the absorption and utilization of nutrients, resulting in digestive problems, loss of appetite, and other issues.

6. Guardian of Antibacterial Protection

Na can disrupt the cell membrane structure of bacteria, inhibiting their growth and reproduction. This can help extend the shelf life of food during processing and preservation.

In conclusion, salt is vital for maintaining life activities. However, it is undeniable that excessive salt intake can negatively impact our health.

II. The Hazards of Excess Salt Intake: From Hypertension to Chronic Diseases

Despite the attention garnered by the notion of "more salt, longer life," multiple long-term studies worldwide have consistently concluded that excessive salt intake is significantly and directly associated with the development of various diseases.

1. The Culprit Behind Hypertension

Global hypertension guidelines widely recommend and emphasize that excessive sodium intake is a significant environmental factor in the development of hypertension. The human body has limited capacity to metabolize salt. For every 0.4g of Na retained, approximately 110g of HO is needed for conversion to maintain water-salt balance.

As blood water content rises, blood volume increases accordingly, leading to increased pressure on the blood vessel walls. Chronic pressure can pose a risk to the heart. Additionally, increased Na promotes the entry of Ca2+ into cells, causing smooth muscle contraction and disrupting intracellular and extracellular K and Na balance, increasing blood viscosity and further intensifying pressure on blood vessel walls.

2. Increased Risk of Cardiovascular Diseases

Chronic high blood pressure has multifaceted detrimental effects on the body. The most significant impact is an increased risk of cardiovascular diseases (such as stroke, coronary heart disease, myocardial infarction, and heart failure). Studies indicate that daily reduction of 400mg of sodium intake (equivalent to about 1g of salt) can significantly reduce the risk of stroke and ischemic heart disease.

3. Hidden Dangers of Stomach Diseases

High salt environments suppress the response of gastric mucosal protective peptides, weakening the self-protective capacity of the gastric mucosa, stimulating excessive gastric acid secretion, and inducing acute and chronic gastritis. Without long-term control, this can increase the risk of cancer. Chronic gastric reflux can also increase the probability of esophageal cancer.

4. Increased Burden on Liver and Kidneys

The consumption of large amounts of salt overwhelms the absorption and metabolic capacity of relevant organs, increasing the burden on the liver and kidneys. Chronic overload can induce chronic or acute organ damage, even increasing the risk of cancer.

5. Risk Factor for Thyroid Cancer

Studies have shown that daily salt intake exceeding 5g (excluding specific populations with family history, disease history, etc.) is an independent risk factor for thyroid cancer.

6. Increased Risk of Chronic Autoimmune Diseases

Excessive salt intake can also alter cell differentiation in the body's immune response, increasing the production of pro-inflammatory factors and leading to chronic autoimmune diseases such as systemic lupus erythematosus, diabetes, and rheumatoid arthritis.

7. Memory Decline and Increased Risk of Alzheimer's Disease

Long-term high salt diets also increase oxidative stress and intestinal inflammation in the hippocampus, impairing memory and cognitive function in the brain, increasing the risk of Alzheimer's disease.

In conclusion, excessive salt intake can contribute to cardiovascular diseases, endocrine system diseases, digestive system diseases, liver and kidney damage, chronic autoimmune diseases, and even increase the risk of certain cancers.

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