Should we all reduce sodium to lower heart disease risk? take this advice with a pinch of salt

Eight thousand years ago our Neolithic ancestors took a break from scratching their arse and making incoherent grunts to set up a thriving community in Romania, under the duress of a hot sun, and with no immediate obvious reward they put in the effort to build a mound three metres high, sixty metres long and twenty-five metres wide to harvest a precious commodity, salt. 

 

Upon this mound, they utilized a local spring, which contained over six times the amount of salt found in Seawater, and using combustible materials managed to boil the water and harvest white gold. 

 

Exactly what did they use it for? Nobody knows, perhaps for making food last longer, or to trade with other tribes, or maybe they just found their chips too bit bland with only vinegar on them. 

 

Over the next few centuries and millennia, salt played a crucial role in the development of our civilisation, the word ‘salary’ comes from the Roman word for salt, but it’s unclear if people were paid in salt or if it refers more to its trading value. 

 

Slaves were certainly traded for salt in Timbuktu, and entire Empires have been created and destroyed in some part due to salt. 

 

So how has this valuable bad boy of the condiment world become demonized in modern times? 

 

Its reputation is in tatters, now a cheap commodity we are warned to cut back on, blamed for 2.5 million deaths per year according to the Word Health Organisation. 

 

There is a lot of confusion on salt in the health and fitness community, whilst most experts are strongly supportive of reducing salt intake, there are a few mavericks claiming that salt should be the least of our concerns. 

 

As an evidence-based Nutritionist and personal Trainer, I wanted to explore the nuance a little more, because I believe that expertise lies in the deeper understanding of where something is applicable and why, and perhaps more importantly, where it is not a concern. 

 

I’ll break this article down into three parts, in the first part I’ll cover the basics of salt, in the second I’ll cover the public health guidance on salt, and in the third I’ll try to cover the nuance, it’s in this last part I hope you’ll get the most benefit. 

A brief run down on salt, to help understand the terms and crux of the main arguments. 

 

Salt is a reference to two elements, sodium and chloride, NaCI, an acid (chloride) and a base (sodium), it has a lot of interesting features that make it useful, a high melting point, good conduction of electricity, ability to soak up moisture, it’s impact on ice, salt is estimated to have over 14,000 uses, including the production of the computer you’re reading this on, and the clothes you’re wearing. Salt is abundant in the ocean waters we evolved from and in all live forms today, salt is absolutely essential for life on Earth. 

 

When Scientist talk about the dangers of salt intake, they are really talking about sodium intake, to find the sodium content we need to divide the amount of salt by 2.54, so the current guideline to consume six grams of salt per day is aimed to limiting sodium to 2300mg. For ease of use, I’ll stick to the word salt throughout the rest of this article. 

 

The main issue with salt is its effect on blood pressure, the amount of fluid pumping through our veins and arteries will determine the amount of pressure those blood vessels have to deal with. So, for example if you spent a day out in the garden working hard in the hot sun, didn’t drink much, and then sat down to relax with a few beers, you would probably become dehydrated, with less fluid pumping through your body, your blood pressure would drop. You might notice this if you got up quickly and suddenly felt light headed. 

 

With me so far? 

 

Now imagine the same scenario, except you’ve kept well hydrated throughout the day, and whilst deadheading your roses, you snack on some salted nuts bought to you on a tray by your stepford loving partner. They also keep the house tidy and always greet you with a smile after a hard day at the office. 

 

So now you have a lot of fluid, and a lot of salt to help draw in that fluid through osmosis (fluid transfer by pressure gradient), which means your veins are pumped up in volume, now you have higher blood pressure than the first scenario. 

 

It’s the difference between a garden hose dripping with weak water pressure and a fire hose blasting out so much water that two people are needed to control the nozzle. 

 

Spend a few years consuming a high salt intake, combined with little inactivity and other lifestyle factors, and chances are you’ll develop high blood pressure (normal is 120 over 80, high is anything above 140 over 90) this in turn will result in much higher risk of death from cardiovascular disease. 

 

When we’re talking about the risk of too much salt, we are really talking about the impact high salt can have on heart health (though obesity is also a risk factor) Let’s start with the public health perspective on salt. 

 

For our awareness of this issue, we can thank Graham Macgregor, professor of cardiovascular medicine at Wolfson Institute of population health and honorary consultant at Barts and the London. Few people in modern times can claim to have saved as many lives as he has through his work and campaigning. 

 

In the 1970s building on research of inhibitors in the Renin Angiotensin system (a group of hormones which help regulate blood pressure and inflammation) he was able to show that even a modest reduction of salt had a significant impact on blood pressure and therefore treatment outcomes for cardiovascular disease. 

 

This was backed up further in wide scale research known as the inter-salt study, which looked at 10,000 men and women aged 20 to 59 belonging to fifty-two populations in thirty-two countries in African, the Americas, Asia and Europe. 

 

After examining various factors, they were able to show that a very low salt intake resulted in low blood pressure. 

 

Of particular significance in this study were the Yanomami Indians who consumed less than ½ a gram of salt per day, yet had very active lifestyles, walking many miles to hunt or gather firewood. All the people of this tribe had low average blood pressure (90 over 60 compared to 120 over 80 in the UK) which didn’t increase with age (defying believes in England at the time that this was just a normal part of aging). 

 

 

So, with all this definitive knowledge you’d think it would be easy to make a big change in public health messaging and guidance to reduce preventable deaths right? 

 

In the 1990s, a conservative government was advised on what action it would need to take to reduce one of the biggest killers at that time, heart disease. One action was to reduce salt intake, but because of pressure from the food industry the government backed down from taking any measures, and so it was the action on salt group was formed. 

 

This eventually led to the food standards agency calling on industry to gradually make big reductions to their salt content over the next few years. 

 

From 2004 onwards the food industry made gradual reductions of salt in their products, which backed up with a public information campaign reduced the amount of salt in the average person’s diet in 2008 from 9.5g to 8.1g, which resulted in approximately 6000 fewer deaths per year, saving about 1.5bn to the UK economy. 

 

Alongside the fewer deaths, blood pressure dropped an average of 2.7 to 1.1 mmHg.. 

 

 

The average consumption of salt in the UK right now is 8.1g per person, per day, the public health goal for the UK is to reduce this to 6g per day, although various experts agree that lower is better, suggesting 3g a day would be ideal. 

 

But where does all of this salt come from? 

 

As a very simple rule, the more processed food you eat, the more salt you’re likely to consume, if your diet is mostly healthy foods then it’s unlikely, you’ll be eating too much salt. In fact, it’s practically impossible, you would have to work really hard to overconsume salt on non-processed foods alone. 

 

Salt in food is usually labelled according to a traffic light system, the following pic was taken from the action on salt website. 

The main high salt culprits are listed below 

 

 

The above list leads me neatly onto the next topic. 

 

 

The more salt in your diet, the more likely you are to be overweight, there are a number of reasons for this, the most obvious one being that increased salt will usually mean increased water retention, so bloating from water weight will account for some of the increase on the scales (there are some athletes who try to manipulate salt in order to make weight, it’s usually quite complex and few people ever get it right) 

 

But most often we’re not just talking about an increase in water, we also mean an increase in fat and sugar, salt helps bring out the flavour in foods, at low levels salt reduces bitterness and enhances sweetness, at higher levels it reduces sweetness and increases umami (one of the five basic taste, the others being sweet, bitter, sour, salty). 

 

As you increase salt you reduce thirst cravings and replace them with hunger cravings. Once you pop you just can’t stop as the saying goes, hunger signals get confused, it’s hard to over consume broccoli, but a pack of crisp just doesn’t seem to satisfy enough, easy to grab another one, maybe add dips, some cheese you say?. 

 

 

The proof of all this salt research and the public health campaigns to reduce salt are in the data, which has shown time and time again that lowering salt consumption is an effective way to improve longevity, one of the few interventions which actually seems to work. 

 

In the late 1950s, it came to the attention of the Japanese government that in the North of their country, they had onoe of the highest number of deaths from strokes in the world. Upon investigating, it became clear that they also consumed a very high amount of salt, mostly from soy. For the next decade, through public health information they managed to reduce salt consumption from 18g a day to 14g and saw a massive 80% drop in stroke mortality. 

 

This came at a time when Japan was becoming more influenced by the west, and increases in smoking, alcohol consumption and fat intake also coincided with the reduction in stroke deaths and lowered blood pressure, suggesting it was the reduction in salt alone which helped improve health outcomes. 

 

A twenty-year public health intervention study which took place in Finland from 1972 involved 14,000 men aged 35-64 and showed a reduction in fat and salt intake, an increase in fruit and veg consumption and a decrease in smoking, helped to lower cholesterol by 13%, diastolic blood pressure by 9%, and stroke mortality by 66%. Overall coronary heart disease deaths also fell by 55%. With the confounding factors, it was estimated about half of the positive health outcomes came from the change in diet and reduction in salt. 

So far it looks like a home run for public health advice, it seems obvious from the research that we should definitely be concerned about how much salt we eat and make an effort to reduce our intake. But hold onto your salty laden pants for a moment partner, there are a few things I haven’t mentioned so far. 

 

Most of the evidence comes from observational population studies, so far there is very little direct research on how a high salt diet, or a reduction in salt can impact on health outcomes, mostly because it would be incredibly hard and super expensive to do this kind of research properly. 

 

Here are some of the counter arguments to consider.  

 

A study by Foo et al in 1998 showed that participants given 15g of salt a day for six days showed no significant increase in either twenty-four hours systolic or diastolic blood pressure. 

 

Those Yanomami Indians I mentioned earlier? Have a life expectancy ten years lower than the UK. I can already here the complaints to that statement, we here on our green and pleasant lands live ten years longer not through our healthier lifestyles, but thanks to our NHS and supportive medication. Nor are we necessarily getting a better quality of life. But never the less the fact that we eat more salt, have higher average blood pressure and are less active doesn’t seem to be having too much of a detrimental impact long term. 

 

Another study by Alderman et al in 2006 reviewed literature relating to sodium and cardiovascular morbidity and could find no causal link. 

 

A study by Gruadal et all showed that too little salt can increase the risk of death, a factor to be considered when people consume a lot of water, become more active and reduce overall salt in their diet in an attempt to improve their health. 

 

Let’s also consider some of the finer points I’ve already mentioned so far, the overall effect of reducing salt intake has resulted in quite minimal changes in blood pressure, just a one or two mmHg. We might expect a bigger impact from increasing activity, losing some weight, improving diet overall and having a healthier lifestyle with less stress (better sleep, meditation etc). 

 

Also take another look at the foods high in salt, if you’re consistently consuming a lot of bread, processed meat, cheese, take aways and salty snacks, then chances are that you are also the kind of person who doesn’t take much exercise, and probably you’re not health conscious enough to take active measures to lower stress, you might even be the kind of person who smokes, or god forbid, claims nectar points you are not entitled too. 

 

It should probably be advised not to add salt to your food, this is indeed good advice for most of people, but if the majority of your diet consist of healthy food then it's probably not a big issue, a little bit of salt on some roast potatoes on a Sunday would pale into insignificance compared to the high salt intake which comes from eating a lot of bread, processed meat, cereals, sauces and fast foods etc.  

 

My point is that there are other factors apart from salt to be concerned with, just focusing on one aspect of diet is always a doomed approach, if most of the salt being consumed comes from processed food, then it’s beyond the control of most of the general public, because we have to live in the real world and realise that attempting to get the whole country to reduce processed food consumption and eat more fruit and veg is a much harder struggle than getting food producers to just reduce the salt in their products. 

 

I'll simplify the above paragraph in order to be more concise with my opinion on this, if I am working with an individual on a private basis, salt might be quite low down on the list of things I would prioritise, but if I was advising on public health, I might well try to force food producers to lower salt content, this is a much easier challenge than trying to get a whole population to cut back on processed food and lead more healthy lifestyles, even though thats exactly what public health messaging should be aiming to achieve.  

 

Reducing salt in bread and other products, still leaves plenty of other additives, unhealthy fats, sugars and flavour enhancers to be conerned with.  

 

Salt does increase blood pressure, that’s undeniable, but only up to a point, so for example if you increase your salt from 5g a day to 8g a day, you will probably see an increase in blood pressure, but going from 8g a day to 12 wouldn’t show a huge difference, at least in the short term. 

 

It’s important to remember that the body is quite good at regulating sodium, the more you eat the more it will piss out, providing you are also eating healthy and being active, and of course properly hydrated. Measuring twenty-four-hour sodium excretion through urine in a laboratory doesn’t tell us much about the long-term implications of salt in our diets, we must take a step back and look at the bigger picture of lifestyle, overall diet and long-term impact. 

 

Adding to this confusing mess is the complex issue of salt sensitivity, it seems there are some individuals who respond better to salt than others, a salt sensitivity test involves reducing salt for four days, followed by four days of increasing salt, whilst monitoring reactions in blood pressure, all under the supervision of doctors. 

 

Those who respond to an increase in salt with a spike in blood pressure are said to be salt sensitive and at an increased risk for hypertension and cardiovascular illness. This may be part of the genetic component linked to heart disease. 

 

In other cases, there are some people who require extra salt in their diet, such as those with salt losing nephropathy (a rare condition affecting the kidneys), or people on diuretic medications, they might at times need to be mindful about their salt intake, and a study from 2017 found that some elderly people had better mental cognition when they ate more salt in their diet.  

 

I should also give a shout out to potassium, this mineral is essential for maintaining healthy blood pressure, people with high blood pressure should also aim for a diet high in potassium rich foods such as potatoes, green beans, lentils, bananas, milk, chicken, broccoli and other fruits, veggies and grains. 

 

By reducing processed foods and increasing non processed foods people will naturally increase their potassium and reduce salt intake. 

 

A final point on salt nuance I should include here is activity levels, the more active you are the more salt your body will use, this doesn’t mean you should focus on increasing salt as you move more, it’s just a note to reassure people concerned about their salt intake that by leading a more active lifestyle they can put some of that salt to use. 

 

One of the few genuine cravings the body will have, is a craving for salt. This has happened to me on a number of occasions, whilst running along the Cleveland way on a 110 mile Ultra run a few years back, I felt myself going dizzy and feeling weak, a marshal looked concerned at a check point as I sank a full bottle of water and nearly cried, unable to speak, I trotted on and a mile or so up the road, after climbing a big hill, my crew met me with my usual snacks, I ate a big handful of salted nuts and felt like magic, it was as if I had taken a life potion in a computer game, I automatically felt stronger and more clear headed. 

 

People often have sweet craving’s which stem more from lust and greed than a genuine need by the body for sugar, but salt cravings are one of the few homeostatic mechanisms we can rely on. 

 

 

 

Should people be concerned about salt? 

 

If they have high blood pressure, if they have heart disease or a history of heart disease, then they should probably be reducing their intake of processed foods, stop smoking, eating more fruit and veg, and lead a healthier lifestyle including more activity, reduced stress and lowering alcohol consumption. 

 

Which is also true for absolutely everyone else, do you get how the nuance works now?