Salt intake could be linked to obesity, say researchers
New analysis from researchers at London’s Queen Mary University suggests that high salt intake is directly linked to obesity, a risk that appears to increase significantly with each additional daily gram consumed.
Increased salt intake has long been known to contribute to high blood pressure and atherosclerosis or arterial hardening, which can lead to stroke and cardiovascular disease but this is the first time obesity has been linked to high salt consumption.
Scientists believe the possible reason for this is that too much salt could affect the body’s metabolism and subsequently its ability to process dietary fats, but stress that further research is needed.
The research, published in the journal Hypertension found that an additional 1g of salt consumed per day was associated with a 26% increased risk of obesity for adults and a 28% increase for children and appeared to be independent of energy intake.
One possible contributing factor to this increased risk could be, say researchers, a tendency for those who eat a lot of salt to crave sugary drinks in order to alleviate the thirst associated with high salt intake.
Professor Graham MacGregor, Professor of Cardiovascular Medicine at Queen Mary University of London and Chairman of Consensus Action on Salt & Health (CASH) says: "The food we eat is now the biggest cause of ill health through its high salt, fat and sugar content added by the food industry. High blood pressure and obesity both lead to the development of cardiovascular disease, stroke, heart attacks and heart failure, which are the commonest causes of death and disability in the UK.
"Obesity also predisposes to type 2 diabetes, which further increases the risks of cardiovascular disease and can lead to severe complications. Such an epidemic will cripple the NHS if the increase in these diet related issues are not stopped immediately. The government and the food industry now need to take much stronger action. Unfortunately the previous government handed power back to the food industry with the Responsibility Deal which has completely failed to tackle these issues in the way that it needs to be."
Researchers analysed data relating to 458 children and 785 adults collated for the UK National Diet and Nutrition Survey (NDNS), examining salt intake in relation to body mass index (BMI) and results showed what researchers describe as a "consistent and significant association between salt intake and BMI, waist circumference and body fat mass".
Victoria Taylor, Senior Dietitian at the British Heart Foundation, says: "It’s well established that we should be reducing the amount of salt we eat to help avoid high blood pressure, a risk factor for cardiovascular disease and the link between salt intake and obesity identified in this research could be another reason for us to do this. But more research is needed to understand what might be the reason for this link. Although the amount of salt we are eating has reduced in recent years, as a result of reformulation of manufactured foods, we are still exceeding recommended maximums.
"Most of the salt we eat is already in the foods we buy, which is why checking nutritional information on packs to make sure we are making the healthiest choice is important to help limit the amount of salt we are eating."
Catherine Collins, Principal Dietitian at St George’s Hospital NHS Trust, St George’s University Hospital says that salt could be an indicator of a high calorie diet which leads to obesity, and not necessarily the cause. She says: "A high calorie diet predisposes to obesity if calories consumed exceed daily needs. Where those calories come from is immaterial. NDNS survey data confirms that our weight increases as we age but our intake of sugar reduces as a proportion of calories consumed.
"I’d interpret the findings to be that in this study a high calorie diet, most likely from savoury rather than sweet foods given the salt intake, predisposes to obesity. Obesity per se increases your risk of hypertension, which is made worse with higher salt food choices. It’s impossible to select out one aspect of a whole diet to critique. It appears that salt is a marker of calorie intake and obesity risk, not necessarily a cause of it."
What are the health risks of a diet high in salt?
NHS Choices says that most of us still consume more salt than we should and warns that high salt intake can result in hypertension or high blood pressure, a condition that affects more than one third of adults in the UK.
Hypertension can lead to stroke, coronary heart disease and heart failure. The British Heart Foundation estimates that up to 7 million people in the UK may be living with undiagnosed high blood pressure.
How much is too much salt?
Salt is an essential mineral that assists in nerve function and, alongside potassium, helps to regulate fluid and electrolyte balance within the body - which is why those suffering from severe and prolonged stomach and bowel upsets need to replace these salts in order to get well.
However, as with many things, moderation is crucial and the increase in the consumption of highly processed and mass-manufactured foods has resulted in daily salt intake that is significantly higher than the body requires.
The NHS recommends a maximum of 2.4 g of sodium per day for adults, which is equivalent to 6g or one teaspoon of salt. For most people, this amount will be consumed via the consumption of pre-prepared and manufactured foods, so there is no need to add salt while cooking foods such as pasta, potatoes or vegetables or at the table.
Babies and children should consume significantly less salt depending on their age due to kidney immaturity, so extra care should be taken when preparing meals and making choices in the supermarket – foods such as stock cubes, yeast extracts and gravies can contain dangerous levels of salt for babies.
Products produced specifically for babies and toddlers typically contain age-adequate levels of salt but it is advisable to always check the label.
For tips on how to monitor and reduce your salt intake, visit NHS Choices.
What's the difference between salt and sodium?
Mention sodium and most people will think of table salt, which consists of 40% sodium and 60% chloride. Other kinds of dietary sodium to watch out for on food labels include baking soda, sodium bicarbonate, sodium benzoate, monosodium glutamate, sodium saccharin and sodium nitrate which are added to foods for their preservative properties, to assist in the rising process during baking or to enhance flavour.
What’s being done about salt in food?
Cutting back on added salt during cooking or at the table is only part of the problem, since many processed and commercially produced meals, packets and sauces still contain high levels of salt – sometimes added for its preservative properties but also to enhance flavour. In addition, many everyday staple foods that many of us consume regularly such as bread, cheese, processed meats and cereals also contain salt, all of which contributes to daily intake. The World Health Organization (WHO) estimates that in industrialised countries 75% of salt intake comes from processed foods.
The Food Standards Agency committed to a national salt reduction initiative which aimed to reduce the UK’s average salt intake to 6g a day back in 2008 and, while great strides towards this goal have been made with many food manufacturers reducing salt levels, CASH says the current average daily intake in the UK remains high at 8.1g so more needs to be done.
If the target 6g is achieved throughout the UK, CASH says strokes could potentially be reduced by 22% and heart attacks by 16%, with an estimated 17,000 lives saved.
CASH is working to reach a consensus with the food industry and the Government to orchestrate a nationwide reduction in salt intake, via negotiating with food manufacturers and supermarkets to continue to gradually reduce salt in food and also campaigns to raise awareness of the issue.
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