Salt and Heart Health: Sodium, Blood Pressure and Everyday Food

Sodium is the component of salt that matters most here. WHO states that the primary health effect associated with diets high in sodium is raised blood pressure. The NHS says eating too much salt can cause high blood pressure, which increases the risk of heart attacks and strokes. WHO's hypertension fact sheet lists a high-salt diet among the factors that increase the risk of hypertension.

Blood pressure is the force of blood against artery walls, and what the two numbers mean is covered in high blood pressure explained. Salt is only one contributor among several, alongside age, weight, activity, alcohol and family history, so cutting back helps but does not guarantee any particular reading.

For adults, WHO recommends less than 2000 mg per day of sodium, which is equivalent to less than 5 g of salt per day, or just under a teaspoon. For children aged 2 to 15 years, WHO recommends adjusting the adult figure downward according to energy requirements. It notes that this does not address infants during exclusive breastfeeding or complementary feeding.

WHO reports that the global mean intake of adults was 4278 mg per day of sodium in 2021, equivalent to 11 g of salt, so most people eat well above the recommended level. Other bodies set slightly different limits. The NHS advises adults and children aged 11 and over to have no more than 6 g of salt (around 1 teaspoon) a day, with lower limits for younger children. The AHA recommends no more than 2,300 mg of sodium a day, with an ideal limit of 1,500 mg for most adults. Which figure applies to you is a question for your own clinician.

The saltshaker is often not the main source. WHO says that in many high-income countries, and increasingly in low- and middle-income countries, a significant proportion of dietary sodium comes from processed foods, which are often high in sodium. It names breads, processed meat and snack foods as examples. The AHA reports that more than 70% of the sodium Americans eat comes from packaged, prepared and restaurant foods. The NHS says packaged everyday foods such as bread, breakfast cereals, meat products and ready meals provide around three quarters of the salt people eat.

Condiments count too. WHO mentions soy and fish sauce as sources, and the NHS lists soy sauce, gravy granules, ketchup and mayonnaise among high-salt sauces. The NHS also suggests choosing low-salt versions of sauces and stock cubes, which implies that standard versions can be salty. Some dissolvable tablets, including certain painkillers and vitamins, may be high in salt, according to the NHS.

Reading labels helps. The AHA notes that the sodium figure on a nutrition label includes sodium from salt and from other ingredients such as monosodium glutamate (MSG), and that the portion you eat may equal more than one labelled serving.

The sources agree on a short list of habits:

• Eat mostly fresh, minimally processed foods, and limit commercial sauces, dressings and instant products (WHO).
• Cook with little or no added salt, and remove the saltshaker from the table (WHO, NHS).
• Use herbs, spices, black pepper, garlic, chilli or lemon juice for flavour (WHO, NHS).
• Taste food before adding salt, and check labels for lower-salt products (NHS).
• Choose tinned vegetables, pulses or fish in water rather than brine, and eat cured meats, cheese, olives and pickles less often (NHS).

For the wider picture of keeping the heart healthy,physical activity and the heart and cholesterol and blood fats cover two other levers.

WHO suggests replacing regular table salt with lower-sodium salt substitutes that contain potassium. The AHA likewise says potassium-based salt substitutes can help prevent or treat elevated or high blood pressure in some adults, especially when most of a person's salt comes from home-cooked food.

Both sources come with a caution that deserves equal weight. The AHA says too much potassium can be harmful for people with kidney disease, for people with any condition that affects how the body handles potassium, and for people on certain medicines, and it advises checking with a healthcare professional before using salt substitutes. WHO's separate guidance on lower-sodium salt substitutes also notes that raised blood potassium may be harmful, especially for individuals with impaired kidney function. The AHA adds that potassium-rich foods such as fruit, vegetables, plantains, yam and fufu supply potassium through food, and that its general advice is to get potassium ideally from diet. Anyone with kidney disease, or taking medicines that affect potassium, should ask a clinician before changing salt or salt substitute use.

If you have high blood pressure, kidney disease, heart failure or take regular medicines, ask your clinician what level of salt is right for you before making large changes, and do not change a medicine because of a diet change. The AHA says its sodium limit may not apply to people directed otherwise by their healthcare team. Chest pain that does not go away, or sudden weakness, numbness or difficulty speaking, needs emergency care; emergency numbers differ by country, so use your local number.

Sodium raises blood pressure, and WHO recommends adults take in less than 2000 mg of sodium (under 5 g of salt) a day. Much of the salt in modern diets comes from processed foods and sauces rather than the saltshaker, so fresh food, label reading and flavouring with herbs and spices are the main tools. Potassium-based salt substitutes can help some people but are unsuitable for others, so ask a clinician first.