Sodium

What is Sodium?

Sodium is an essential mineral that the body needs in small amounts to function properly. It is the most abundant electrolyte, electrically charged particles, in the body and is needed for maintaining fluid balance, and supporting muscle and nerve function.

• Fluid balance

  Sodium has a critical role in supporting your cells to maintain the right balance of fluid. It regulates the amount of water in and around the cells, drawing fluid into the extracellular space when required, this keeps the sodium gradients inside and outside the cell equal^[1].

• Muscle contraction

  Working with other electrolytes, like potassium and magnesium, sodium facilitates muscle contraction, enabling you to carry out normal daily movements but also ensuring your heart beats efficiently.

• Nerve function

  Sodium helps generate and transmit nerve impulses, an important communication pathway between the brain and the rest of the body. Sodium and potassium maintain the nerve impulses through sodium-potassium pumps. These move three sodium ions out of the cell and allow two potassium ions in, forming action potentials. When one cell communicates with another, the channel opens, allowing sodium to enter, this fires off a nerve cell which travels to the brain or muscle to deliver its message. The message could be for the muscle to contract or for the brain to initiate an action.^[2]

Despite its importance, sodium intake must be carefully managed because too much or too little can cause health problems. A diet high in sodium, for example, is associated with high blood pressure because sodium can draw water into the blood, increasing blood volume, and consequently, blood pressure^[3].

Normal Sodium Blood Levels

The reference range for sodium may differ between testing laboratories.

The NHS states that blood sodium levels should be between 133 and 145 mmol/L^[5].

Managing Your Sodium Levels

Managing sodium levels is critical for maintaining good health and avoiding heart disease, high blood pressure, kidney disease, and dehydration. First, it’s important to understand if your levels are high or low, so you can make changes to help bring them back to within a normal range.

Causes and Symptoms of Low Sodium

Low blood sodium levels are called hyponatraemia. In most cases, it is caused by too much water diluting sodium, causing water to move into the body’s cells and making them swell. If this happens in the brain, the consequences can be serious.

Hyponatraemia is rarely caused by losing too much sodium from the body, perhaps because you have a severe or prolonged stomach bug or are taking diuretics.

Some of the potential causes of low sodium are:

• Lifestyle factors

  Excess water intake, excessive exercise, malnutrition, severe burns

• Medications

  Diuretics, selective serotonin reuptake inhibitors (SSRIs), carbamazepine

• Underlying health conditions

  Kidney disease, liver disease, heart failure, addison’s disease, underactive thyroid (hypothyroidism), severe sickness and diarrhoea

The symptoms of hyponatraemia can vary depending on the severity and how quickly they fall. If sodium levels fall rapidly, the symptoms are likely to be more serious and cause seizures and coma.

Some of the common symptoms include:

• Muscle cramps

• Feeling or being sick

• Low energy

• Headaches

• Confusion^[7]

Improving Sodium Levels

If your sodium levels are severely low, you will need medical attention to find out the underlying cause and to receive appropriate treatment.

If you have mild symptoms, there are things you can do to help, such as:

• Lowering your water or fluid intake

• Reviewing existing medications alongside your doctor

• Adjusting your diet or exercise plan

Low sodium levels can occur if you sweat a lot during exercise and you do not replace them with electrolyte replacement drinks. When exercising you need to make sure you are replacing the fluid and the sodium you lose in sweat and urine.

What should I eat if my sodium level is low?

Eating a healthy, balanced diet that incorporates lots of fruit, vegetables, and wholegrains as well as foods that have high value protein can help to keep your sodium levels within a normal range. They include:

• Lean meat

• Poultry

• Eggs

• Fish and seafood

• Nuts and seeds

It’s also a good idea to limit your alcohol intake. Alcohol can increase your urine output which means you may lose sodium.

Causes and Symptoms of High Sodium

High blood sodium levels, also called hypernatraemia, occur when levels are above 145 mmol/L. It represents a health state where there is an inadequate supply of water in relation to sodium. Hypernatraemia is more common in people who are in hospital, have limited access to water, newborns, and the elderly^[8].

Low sodium levels occur because of a net water loss or an increased sodium intake. It can be caused by:

• Dehydration

• Being sick

• Watery diarrhoea

• Fever

• Dementia

• Uncontrolled diabetes

• Severe burns

• Kidney disease

• A rare condition called diabetes insipidus

Older adults are most at risk of hypernatraemia because of the reduced sense of thirst.

What is a symptom of too much sodium?

If sodium levels are only slightly raised, you may not experience any symptoms.

If your levels are extremely high or if they have increased rapidly, then it’s more likely that symptoms will appear, such as:

• Increased thirst

• Feeling or being sick

• Muscle weakness

• Restlessness

Decreasing Sodium Levels

The treatment for hypernatraemia will focus on the underlying cause to help correct the sodium and water imbalance. It may include rehydration through oral or intravenous fluids.

However, there are things you can do to help keep your sodium levels within a normal range.

Diet

Although eating a diet high in sodium on it’s own is unlikely to cause dangerously high blood sodium levels, it can cause other health problems, particularly high blood pressure and cardiovascular disease^[10].

The NHS recommends that anyone in the UK over 11 years old should eat not more than 6g of salt per day. That’s equivalent to one teaspoon^[11].

Some of the high sodium foods you should look to avoid or reduce are:

• Canned soups

• Deli and processed meat

• Pizza

• Bread

• Some breakfast cereals

• Sauces and condiments

• Ready meals

• Dairy

• Shellfish

• Canned tuna

Does drinking water lower sodium?

It is important to stay hydrated throughout the day to keep your water and electrolytes in balance. Sipping little and often throughout the day is more beneficial than taking big gulps when you are thirsty, because thirst is an early sign of dehydration.

Written by Leanne Edermaniger

Based in the UK, Leanne specialises in writing about health, medicine, nutrition, and fitness.

She has over 5 years of experience in writing about health and lifestyle and has a BSc (hons) Biomedical Science and an MSc Science, Communication and Society.