The number
The World Health Organization's recommendation for adults is less than 2 g of sodium a day, which is less than 5 g of salt. That is one level teaspoon, and it counts all the salt of the day: what goes into cooking, what is in the bread, the cheese, the ham, the packet soup and whatever is eaten out. Most people, when asked, think of the salt shaker; the shaker is the small part.
How much we eat in Portugal
There are two measures, and both say the same. In the PHYSA study by the Portuguese Society of Hypertension, sodium was measured in 24-hour urine from a representative sample of adults in 2011 and 2012, which is the most reliable way to know how much salt went in: it came to 10.7 g a day, almost double the recommendation. In the National Food Survey of 2015 and 2016, done by interview about what was eaten, the average was 7.4 g a day. Interview surveys always fall below what urine shows, because nobody remembers all the salt; the true value will be between the two, and in any case above 5.
Why it matters
Salt raises blood pressure, and blood pressure is the main risk factor for heart attack and stroke. The meta-analysis by Feng He and colleagues, in 2013, pooled 34 trials in which salt was reduced for at least four weeks: with 4.4 g less a day, systolic blood pressure fell on average by 4.2 mmHg and diastolic by 2.1. In people with hypertension the fall was larger, 5.4 mmHg; in people without hypertension it was smaller, 2.4, but it was not zero.
In 2021, Tommaso Filippini and colleagues pooled 85 trials in a dose-response analysis and found a near-straight line: with each gram of sodium less, blood pressure falls a little, across the whole range of intake, with no floor below which it stops counting. At world scale, Dariush Mozaffarian and colleagues estimated in 2014 that 1.65 million cardiovascular deaths a year were due to sodium intakes above 2 g. And in the Global Burden of Disease estimates for 2017, excess sodium was the dietary factor with the greatest weight in diet-attributable deaths, ahead of too few whole grains and too little fruit. These are population numbers, not one person's; they give the direction, not what happens to each.
Where the hidden salt is
In Portugal, the food that brings most salt to the table is bread, not because it has a lot, but because a lot of it is eaten. The 2009 law set the maximum at 1.4 g of salt per 100 g of baked bread; a 50 g roll can have 0.7 g, and two at breakfast are more than a quarter of the day. Then come cured meats and ham, cheeses, packet soups and stock cubes, sauces, savoury biscuits, tinned food and ready meals. And everything eaten away from home, where you do not see what went in.
The salt added in cooking and at the table is, in most homes, the smaller fraction. That is why "removing the salt shaker" changes little, and changing what you buy changes a lot.
How to read a label
- Salt, not sodium. Labels in the European Union state "salt" per 100 g. If you find a label in sodium, multiply by 2.5: 1 g of sodium is 2.5 g of salt.
- Per 100 g to compare; per portion to count. The 100 g column is for comparing two products; the portion column is for adding up the day.
- A rule of thumb: up to 0.3 g of salt per 100 g is low; above 1.5 g per 100 g is high. In between, it depends on how much you eat.
- Foods without a label (the baker's bread, cheese from the counter, the restaurant meal) are the ones that surprise most. Asking costs nothing.
What to do
- Start with what you buy. Swap everyday ham and cured meats for lower-salt alternatives, or for fewer times; choose the bread with less salt when there is a choice; read the label on soups, sauces and biscuits.
- Cook with half and make up for it with herbs, garlic, lemon, spices and pepper. In the trials by He and colleagues, the reductions lasted four weeks or more; that is the time the palate takes to readjust.
- Taste before salting. The automatic reach for the shaker is the easiest to drop.
- Count one day, with labels and a measuring spoon, just to see where the salt is. Once is enough to change what you buy.
- Fruit and vegetables every day. They bring potassium, which works in the opposite direction to sodium, and they take the place on the plate of what has more salt.
Anyone with hypertension, kidney disease or on blood pressure medication benefits more from cutting salt, and should talk about it in the appointment, with their blood pressure values to hand. The nutrition page says what is asked and what is measured; what to do with your numbers is a conversation for there.