31 August 2017 at 16:26
To salt or not to salt?
Can salt be beneficial to blood pressure? Earlier this year a large, long term study found that a low sodium diet wasn’t beneficial to blood pressure. This goes against medical advice that has been widely accepted for decades, with health professionals regularly telling patients with high blood pressure to eat less salt. So have we been wrong the whole time?
The latest findings of the Framingham study add to growing evidence that the recommendations on sodium intake are due for review. The original study started in the 1940’s and tracked the cardiovascular health of over 5000 residents of the town of Framingham, Massachusetts. An offspring study – tracking children of the original cohort - commenced in 1971 and provided these surprising results.
The current guideline for sodium intake in adults is 2.4g per day (equivalent to 6g table salt); however, the Framingham study found that those consuming between 2.5 and 4g of sodium had significantly lower blood pressure than those on a lower sodium diet. Even more surprising is that the lowest blood pressure recorded was amongst participants consuming over 4g a day – a level which is generally considered dangerously high. With average intakes in the UK estimated to be around 3.2g per day, we might start to question whether our sodium intake is a problem after all.
The good news is that the study supported what we already know about blood pressure and other minerals. High intakes of calcium, potassium and magnesium were associated with lower blood pressure, and individuals with the lowest blood pressure were found to have the highest intakes of potassium. The researchers also noted that 20-25% of the population may be ‘salt sensitive’, so a reduced salt diet would be appropriate for some.
Studies that have provided evidence for low sodium diets have generally been conducted over relatively short periods (weeks or months) whereas the Framingham study used data collected over a period of 16 years, and so is one of the only studies that examines the long term impact of diet on blood pressure.
You might have heard of DASH (Dietary Approaches to Stop Hypertension) – a diet which is high in fruit and vegetables and low in fat, salt and alcohol. The DASH diet has shown significant benefits on blood pressure after just 2 weeks and has undoubtedly been beneficial to many. It’s worth noting that vegetables are a rich source of potassium, so it may well be the high level of potassium rather than the low sodium which makes DASH effective.
But before you start adding salt to your food it’s important to remember that sodium affects more than just blood pressure – naturopaths have long argued that sodiumisation of the cell is at the root of many chronic health conditions, and a good sodium/potassium balance is fundamental to health. There are also a number of non-dietary factors which affect blood pressure such as age, gender, ethnicity and long-term stress to be taken into account.
This latest piece of research just highlights how unique each individual is when it comes to diet and nutrition.
To discover more about the links between diet and health, consider an introductory course in Nutrition – current courses can be found here.