Small amounts of salt are essential for our health. Adults need less than 1 gram per day and children need even less. But many of us eat far more salt than we need, putting us at risk of some health problems. Here are some of them.
Blood pressure is the amount of pressure that blood puts on your blood vessel walls as it is pumped around the body. Certain factors such as being overweight, lack of exercise and, in particular, a high salt diet can raise your blood pressure, leading to heart attacks and strokes. A third of adults have high blood pressure, defined as 140/90 mmHg, and many don’t even know they have it as it has no symptoms.
A stroke usually occurs when the blood supply to part of the brain is cut off, reducing the flow of oxygen to the brain, causing cells to die. There are two main types of stroke; ischemic strokes, when a blood vessel becomes blocked, and haemorrhagic strokes, when a blood vessel bursts and bleeds into the brain. High blood pressure is the single most important risk factor for stroke and salt is the major factor that raises blood pressure, salt is therefore responsible for many of these strokes.
Coronary heart disease
Coronary heart disease (CHD) is the term used to describe what happens when the heart’s blood supply is reduced or blocked leading to heart failure and heart attacks. Raised blood pressure is a major risk factor for CHD. It causes the walls of blood vessels to become thick so that the blood vessels become too narrow and can’t carry enough blood to the heart. Over time this can lead to a thickening of the heart muscle, reducing the heart’s ability to pump blood around the body, leading to heart failure – where not enough blood is carried around the body. The thickened blood vessel walls can also lead to clots forming; these clots can block the blood supply to the heart and cause a heart attack.
As raised blood pressure is a major risk factor for CHD and salt raises blood pressure, lowering salt intake, losing weight and making other lifestyle changes can dramatically reduce your risk.
A high salt diet increases the risk of stomach cancer. A quarter of the 7,000 new cases each year can be attributed to salt. The bacterium Helicobacter pylori (H. pylori) is the major risk factor for stomach cancer, as it can lead to inflammation of the stomach which can in turn lead to stomach ulcers and stomach cancer. H. Pylori in the stomach will not necessarily cause damage, however salt can damage the lining of the stomach, making it more vulnerable to the effects of H.pylori, and salt may also increase the growth and action of the bacterium making it more likely to cause damage.
Osteoporosis is a condition which causes thinning of bones, making them brittle and prone to breaking. Most calcium in the body is stored in bones. A high salt diet can cause calcium to be lost from bones and excreted in the urine, making bones weak and easily broken. High blood pressure caused by a high salt diet can speed up the loss of calcium from bones, worsening the problem.
Kidney stones and kidney disease
Kidney stones are a common problem, caused by a build-up of calcium in the kidneys. Both a high salt intake and high blood pressure can cause too much calcium to be excreted by the kidneys into the urine, leading to a build-up of calcium and, therefore, kidney stones. They can be very painful and, in some cases, can lead to kidney disease.
The kidneys control fluid balance and blood pressure by controlling the amount of fluid lost from the blood into urine. A high salt diet can disrupt the function of the kidneys and cause high blood pressure, this in turn puts a strain on the kidneys leading to kidney disease. A high salt diet can also cause existing kidney disease to progress faster. People with kidney disease, or at risk due to persistent urinary tract infections or Chrohn’s disease, should reduce their salt intake to avoid exacerbating the condition.
Dementia is a loss of brain function that affects memory, thinking, language, judgment, and behaviour. Vascular dementia is a common form of dementia. It is caused by a blocked blood vessel in the brain which occurs after a stroke or a series of mini strokes; around one in three people who have a stroke develop vascular dementia. A high salt intake raises blood pressure, increasing the risk of stroke and, therefore, the risk of dementia. Good blood pressure control is hugely important in preventing strokes so keeping salt intake down in younger life, along with leading a healthy lifestyle, can be recommended as part of a preventative diet.
A high salt intake causes us to retain water, up to 1.5 litres(!) of it. Women who find they suffer from bloating may see a benefit from salt reduction and, more seriously, patients already with heart failure, nephrotic syndrome and cirrhosis of the liver, will particularly benefit in a cut in salt intake
Asthma is a common condition which affects 1 in 11 children and 1 in 12 adults. A high salt diet is not thought to cause asthma, but some studies have shown that it can aggravate symptoms. If your child suffers from asthma, reducing their salt intake may be beneficial in combination with the other treatments for asthma.
Ménière’s is a rare disease which damages the ear and causes giddiness with nausea and vomiting, tinnitus and hearing loss. A high salt diet can worsen the symptoms of Ménière’s because it causes fluid retention, this can increase the pressure in the inner ear which causes and worsens the symptoms of Ménière’s. A lower salt diet is thought to be extremely effective in treating Ménière’s.