New research shows that too little potassium, as well as too much or too little salt, can cause health problems. So how much of each should we eat and what are the best foods for delivering these essential micro-nutrients?
The importance of both salt and potassium in the diet was illustrated by a research paper published in the New England Journal of Medicine in August 2014.
This study—of almost 102,000 adults—found that blood pressure levels are associated with both sodium and potassium intake.
Sodium levels that are either too high or too low raise blood pressure, and high levels of potassium lower blood pressure.
The researchers concluded that an estimated intake of between 3g and 6g of salt (1.2g to 2.4g of sodium) a day was associated with a lower risk of cardiovascular events than either higher or lower levels. It also found that consumption of more than 1.5g of potassium a day was associated with a reduced risk of heart disease.
Sodium is an essential nutrient. However, because it retains excess fluids in the body, sodium increases blood pressure and so places an added burden on the heart.
If you are a type 2 diabetic, there is an 85% chance that you also have issues with your blood pressure. In addition, blood pressure tends to rise as you grow older.
Eating less sodium can help you control your blood pressure, which will reduce the risk that you develop stroke, heart failure, osteoporosis, stomach cancer, kidney disease and other associated medical conditions as time goes on.
But gaining control over the amount of sodium you eat can be difficult because about 75 percent of it comes from salt added to processed foods and restaurant foods. It’s hard to limit you intake when the food you eat already contains lots of sodium.
Besides the sodium we ingest through salt added at the table or during cooking or the production of processed foods, there are several other sources of sodium in our diets.
Reading food labels you’ll notice ingredients such as ‘soda’ (sodium bicarbonate, aka baking soda) and ‘sodium’ (in compounds such as sodium nitrate, sodium citrate, monosodium glutamate (MSG) and sodium benzoate). So you can get sodium in many foodstuffs, even those that don’t taste salty.
It is estimated that, by 2020, nearly two-thirds of adults in the Western world will have high blood pressure due mainly to over-consumption of salt. Learning to read food labels is vital if you are to control your daily intake of sodium.
Potassium is a dietary mineral. It is very important for the proper functioning of your cells, tissues, and organs. It is also crucial for the functions of your heart and plays a key role in the smooth contraction of muscle, making it vital for normal digestive and muscular functions.
Eating foods containing potassium is necessary for controlling blood pressure because it blunts the effects of sodium.
In fact, the more potassium we eat, the more sodium we pass out of the body through urine.
Potassium also helps relax blood vessel walls, which too helps lower blood pressure.
Dietary guidelines for sodium and potassium
Guidelines on the amount of sodium and potassium you should ingest daily vary widely from country to country and are contradictory.
In 2014 the World Health Organisation (WHO) was recommending 2g of sodium (5g of salt) and at least 3.5 g potassium a day for adults.
By contrast the American Heart Association was recommending no more than 1.5g of sodium (3.75g of salt) and at least 4.7g of potassium a day for adults—significantly less salt and more potassium than the WHO’s recommended daily intakes.
Which is the better guideline?
I don’t know. It is obvious, however, that the less salt and the more potassium we take, the better it is for our health.
But how do we go about doing this?
Here’s a neat trick.
You can group foods into three categories according to their salt and potassium content.
Group One … are fresh whole foods and food that have been subjected to minimal processing (such as cleaning, drying, canning, bottling and cooking).
Group One foods are vegetables, grains and fresh or frozen meat and fish. Most Group One foods contain little added salt and lots of potassium.
Group Two … are products made from Group One foods, such as oil from olives, flour and pasta from grains and so on.
Foods in Groups One and Two are used to prepare freshly-made meals.
Group Three … are processed foods made by transforming foods in the other two groups. These foods are usually high in salt, fat and sugar, which enhance their flavour and make them addictive.
Examples include sausage rolls, crisps, delicatessen meats, pizzas, canned soups, burgers and chicken nuggets, other ready meals and some types of bread. You’ll find thousands of examples in any supermarket or fast-food joint.
Group Three foods are mainly responsible for high levels of obesity, high blood pressure and chronic diseases in developed countries where they are tending to replace foods in the other two groups.
A low-sodium and high-potassium diet
The best thing to do—if you really want to reduce your sodium intake and increase you intake of potassium—is to buy foods from Groups One and Two only and avoid consuming Group Three foods as far as possible.
In practical terms this means going for a diet that is rich in fruits, vegetables, fat-free or low-fat substitutes for animal milk (such as soy milk), whole-grain foods, fish, poultry, beans, and seeds.
As well as having less sodium, this diet avoids sweets, added sugars and drinks containing sugar, saturated and trans-fats. It will also have less red meat than the typical Western diet. It also means cooking meals from scratch with no added salt.
This diet is the same as the plant-focused diet—low in sugar, low in fat, low in salt, high in fibre and digested slowly—I use to control my diabetes successfully. I also avoid all dairy products and eggs, and drink plenty of water.
Because it is low in salt and consists mainly of fresh foods, and avoids processed foods, this diet reduces your salt intake to the minimum necessary to control blood pressure.
But does it deliver adequate potassium?
Dietary sources of potassium
Assuming that the American guidelines are superior to the UN’s recommendations, you need to ingest more than 4.7g of potassium a day. I go for 5g a day!
Most westerners do not get nearly that much. On average, adult males in the West eat almost 3.2g a day, and adult females about 2.4g a day.
Good natural sources of potassium are fruits, vegetables, fat-free or low-fat soy milk or other milk substitutes, and fish such as tuna and mackerel.
For example, a medium banana has about 420 mg of potassium, and half a cup of plain mashed sweet potatoes has 475 mg.
Other potassium-rich foods include:
- Lima beans
- Tomatoes, tomato juice and tomato sauce
- Oranges and orange juice
- Cantaloupe and honeydew melon
- Prunes and prune juice
- Apricots and apricot juice
- Raisins and dates
- Fat-free non-dairy milk
- Fat-free non-dairy yogurt
Note that if you concentrate only on vegetables then, to get enough potassium, you will need to consume the equivalent of four cups of cooked greens every day.
So you may need to up your potassium intake with an over-the-counter supplement.
Be careful though. Potassium affects the balance of fluids in the body. As we get older, our kidneys become less able to remove potassium from our blood, so too much potassium can be harmful in older people and those with kidney disorders.