Healthy eating gets more complicated every day. New research into salt intake shows that too little or too much salt can cause health problems.
Several papers published last month in the New England Journal of Medicine describe the importance of both salt and potassium in the diet.
One survey measured sodium intake of adults in 66 countries and found that 1.65 million deaths from cardiovascular causes in 2010 could be attributed to sodium consumption above a daily reference intake of 2g.
Another study of 101,945 adults found that blood pressure was associated with both sodium and potassium intake. High sodium levels raised blood pressure, and high potassium levels lowered blood pressure. An estimated sodium intake of between 3g and 6g a day was associated with a lower risk of cardiovascular events than either higher or lower levels. Consumption of more than 1.5g of potassium a day was associated with a reduced risk of heart disease.
Confusing terminology
The terminology used in the studies is confusing because researchers measured levels of sodium, not salt.
Sodium is not the same as salt. Table salt is made up of two minerals, sodium and chloride, so daily salt intake must be divided by 2.5 to calculate sodium intake.
Guidelines on sodium and potassium vary from country to country. World Health Organisation (WHO) guidelines for 2014 say "adults should consume less than 2g of sodium or 5g (one teaspoon) of salt and at least 3.5g of potassium per day" and that "most people consume too much sodium and not enough potassium". These amounts include salt in food as well as salt added at the table.
Guidelines from the Food Safety Authority of Ireland (FSAI) say "adults should consume no more than 6g of salt or 2.4g of sodium per day (children should have far less)". No levels are recommended for potassium.
According to the FSAI, most Irish adults “continue to exceed the recommended daily intake of 6g of salt per day”.
The American Heart Association recommends no more than 1.5g of salt and at least 4.7g of potassium. Which guidelines should be followed?
It seems that the less salt and the more potassium we take, the better.
Foods can be categorised into three groups based on salt and potassium content.
Group one contains fresh whole foods and foods that have been subjected to minimal processes that make them more accessible, available and safer. These processes include cleaning, pasteurisation, drying, canning and bottling. Most of these foods contain little added salt and lots of potassium.
Group two consists of products made from group one foods such as oil from olives, and pasta and flour made from cereal. Foods in groups one and two are used to prepare meals.
Group three contains heavily processed food made from transformed group two substances. These are usually high in salt, fat and sugar to make them more palatable and habit-forming.
Designed to be “ready to heat” or “ready to eat”, they include sausage rolls, chicken nuggets, crisps and microwaveable meals.
Group three food substances have almost replaced real food in many countries and are largely responsible for the current high rates of obesity, high blood pressure and chronic diseases.
High blood pressure
The
Institute of Public Health
estimates that by 2020 almost two-thirds of Irish adults will have high blood pressure due to overconsumption of salt and other unhealthy habits.
It is hard to limit salt intake to the 5g recommended by the WHO. Even nutritious foods such as cheese and tinned tuna contain salt.
Potassium, which lowers blood pressure, is found in fish (salmon, mackerel) and vegetables (spinach, broccoli, cabbage and baked potatoes). An adult needs to consume the equivalent of four cups of cooked greens every day to get enough potassium.
Most people never think about daily reference intakes and ignore healthy eating guidelines because they are complicated and often contradictory.
Others worry and are constantly on diets of one kind or another.
Either way, all the advice about what and how much to eat can ruin the enjoyment of food. The best approach is to buy food from only groups one and two and prepare or cook meals from scratch with no added salt. Ignore all food advertising which is designed to encourage the purchase of food products from group three.
Have you noticed how the eyes of babies fed “follow-on milks” glisten and sparkle in television ads? These milks, like all group three foods, are unnecessary, and claims for their health-giving properties should be taken with a pinch of salt.
drjackyjones@gmail.com Dr Jacky Jones is a former HSE regional manager of health promotion and a member of the Healthy Ireland council.