Salt and your blood pressure

Eating too much salt is the single biggest cause of high blood pressure.

The more salt you eat, the higher your blood pressure will be.

Because salt is often hidden in the foods we buy, it can be hard to know how much you’re eating or how to cut back. Here, you can find out how. 

How does salt raise your blood pressure?

Salt makes your body hold onto water. If you eat too much, the extra water in your blood means there is extra pressure on your blood vessel walls, raising your blood pressure.

If you already have high blood pressure, too much salt will raise it further, and may mean that any blood pressure medicines you’re taking don't work as well as they should.

Cutting down on salt is one of the simplest ways to lower your blood pressure, and will start to make a difference very quickly, even within weeks.

Eating too much salt can lead to all the health problems high blood pressure causes, including heart disease, stroke, kidney disease and some types of dementia. 

Salt and your kidneys

Your kidneys play an important role in removing fluid and waste products from your body and in controlling your blood pressure. Eating too much salt makes them less able to do their job, raising your blood pressure and leading to kidney disease.

Your kidneys filter out excess fluid from your blood, which then collects in your bladder to be removed as urine. They draw water out of your blood through osmosis – where the water travels from the blood which is relatively low in sodium into channels which are higher in sodium – sodium is the part of salt that raises your blood pressure.

Eating too much salt raises the amount of sodium in your blood, throwing off this fine balance of sodium and water, and damaging the tiny blood vessels in the kidneys.

Over time, the extra strain can damage the kidneys, leading to kidney disease. The kidneys are less able to do their job, raising your blood pressure and allowing fluid and waste products to build up in your body. Eventually this can lead to kidney failure and all the problems caused by high blood pressure, such as heart disease and stroke.

As well as eating less salt, eating more potassium will help to look after your kidneys and your blood pressure – as potassium is involved in the process of drawing water from your blood and into your kidneys. 

Eating less salt can help your blood pressure medications to work

If you have high blood pressure and you’re taking a diuretic medication, this will help the kidneys to remove fluid from your blood. The sodium in salt counteracts this effect of the diuretics, stopping them from working well.

Eating less salt will allow your medicines to work and your kidneys to do their job, lowering the amount of excess fluid in your blood and lowering your blood pressure.

How much salt is too much?

Adults should eat less than 6g of salt a day, but most of us eat much more. The latest figures show we’re eating around 8g a day on average.

Most of the salt we eat is hidden in the foods we buy ready-made, like bread, biscuits, breakfast cereals, sauces and condiments, as well as ready meals and takeaways. This hidden salt accounts for around three quarters (75%) of the salt we eat, only a small amount comes from the salt we add while cooking or at the table. 

How to eat less salt

By learning some simple food swaps, understanding food labels and adding different flavours while cooking, you can slash your salt intake and still eat delicious food.

Tips for eating less salt

These ideas will help you get started.

• Don’t add salt when cooking. Try adding different flavours and allow a little time for your taste buds to adjust.
  
  
• Avoid very salty flavourings. Ready-made sauces, soy sauce, stock cubes and gravy granules can all be very salty, look out for low salt options or try some new flavourings.
  
  
• Get extra flavour into your recipes. Add herbs, spices and seasonings like chilli, pepper, ginger, lemon or lime juice.
  
  
• Taste food before you add salt. Sometimes people add salt out of habit, remember to taste your meals first.
  
  
• Take the salt shaker off the table. So you're less likely to be tempted.
  
  
• Be careful of condiments. The salt shaker’s fellow table dwellers can be very salty too, like mustard and ketchup.
  
  
• Try a salt alternative. If you really can't do without a salty favour, try using a small amount of a low-sodium salt substitute.
  
  
• Make your own marinades. Marinating meat or fish in lemon or lime, or with yogurt and spices, avoids the need to add salt for flavour.
  
  
• Cut down on high salt foods. Cooking sauces, table sauces such as ketchup and mustard, cheese, bacon, olives and pickles can contain a lot of salt.
  
  
• Check the labels. Salt contents vary greatly. Check the labels of foods before you buy them and compare with other products – you’ll often find lower salt low-salt options.
  
  
• Choose low salt bread and breakfast cereals. They can contain a lot of salt and add a lot to our diet – as we eat so much of them. Check the labels to compare brands.
  
  
• Avoid smoked and processed meats and These contain a lot of salt, so limit how much you eat.
  
  
• Call ahead when you eat out. If you are eating out, ask if your meal can be made with less salt. This isn’t always possible, but it’s always worth asking, and there may be options with less salt than others.
  
  
• Use the FoodSwitch app. It compares the salt content of similar products so you can find the healthier options easily.
  
  
• Don’t give up. If food tastes bland to start with, don’t give up. After a few weeks your taste buds will adjust and you will start to enjoy food with less salt – like switching to tea without sugar.

Which foods are high in salt?

Certain foods are particularly high in salt. Try to avoid them or find a lower-salt version:

• tomato ketchup
• tinned, packet and chiller cabinet soups
• beef, chicken and vegetable stock cubes
• gravy granules
• soy sauce
• dried fish
• mustard
• pickles
• curry powders
• ready-made sandwiches
• microwave and frozen ready meals
• breaded chicken products
• sausages
• bacon
• ham

You can also download the free FoodSwitch app which does the hard work for you. By scanning the barcode of a product the app will tell you how much salt it contains and offer suggestions for a similar but healthier alternative.

Understanding food labels

Most of the salt we eat is hidden in the foods we buy, and similar products can vary dramatically in how much salt they contain. For example, two loaves of bread made by different companies may appear to be basically the same, but when you check the labels one contains 1g of salt per slice while the other contains half that.

Check the nutrition information on food labels to see if it’s low, medium or high in salt, and compare with other products to find the healthy options.

Checking labels for salt

Follow these guidelines to choose lower salt foods.

• Low - 0.3g salt or less per 100g - Eat plenty of these.
• Medium - 0.3-1.5g salt per 100g - These are usually fine to eat, but choose low salt options where you can
• High - 1.5g salt or more per 100g - Try to avoid these or eat them only occasionally

Checking labels for sodium

Salt is made up of sodium and chloride, and it’s the sodium that raises blood pressure. 1g of sodium is the same as 2.5g of salt. 

By law, companies have to list the salt content of food on the packaging but some imported foods list the sodium rather than salt.

Follow these guidelines to choose lower sodium (and salt) foods.

• Low – 0.1g sodium or less per 100g - Eat plenty of these.
• Medium – 0.1-0.6g sodium per 100g - These are usually fine to eat, but choose low salt options where you can
• High – 0.6g sodium or more per 100g - Try to avoid these or eat them only occasionally.

Look for traffic lights

Many food products have colored labels on the front of their packets. They are color coded with red meaning the food is high in salt, amber is medium and green is low. Look out for green labels for salt as much as possible and avoid red.

Checking the ingredients

If the label doesn’t say how much salt or sodium a food contains, look at the ingredients list. The closer to the top salt appears, the more salt it’s likely to contain.

Learn more about understanding food labels. 

Cooking with less salt

There are lots of flavours you can add to your meals to delight your taste buds, without raising your blood pressure.

Ingredients you can use to add flavor include:

• fresh, frozen or dried herbs
• onions
• garlic
• shallots
• chillies
• ginger
• cinnamon
• cumin
• lemon juice
• pepper
• vinegar
• red or white wine, cider or beer
• ready-mixed spices – but check the label to make sure that they only contain low levels of salt or sodium

Have a look at our low salt recipes for ideas.

Be careful of salt that is marketed as healthy

Many table salt products market themselves as healthy options, claiming to be natural or from a healthy-sounding source. For example, sea salt, rock salt, pink Himalayan salt, garlic salt and natural salt.

Because of this, many people believe that these forms of salt must be better for them and are fine to use.

Unfortunately, salt is salt. They all contain the same amount of sodium so they all have the same effect on your blood pressure and your body.

If you can’t live without adding some salt to your food, you could try a low-sodium alternative.

Low-sodium salt alternatives to salt

There are low-sodium alternatives to salt which you can buy to season your food. These give food the same salty flavor but contain much less sodium.

These products contain potassium instead of sodium so they could help you to lower your blood pressure if you find it too hard to cook without adding salt.

These products include LoSalt, and there are other brands available.

If you have kidney problems or diabetes, check with your doctor or nurse before using the products as they might not be suitable for you.

Sodium in medications, supplements and pick-me-ups

Effervescent (fizzy) and soluble tablets and powders that you add to water contain sodium carbonate or sodium bicarbonate to make them fizz. For example, vitamin C supplements like Berocca, and soluble painkillers such as aspirin and Alka Seltzer. 

The amount of sodium in these products can be equivalent to 1g of salt. This can really add to your daily salt intake so try to avoid these and use tablets instead.

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