The research proving that salt causes high blood pressure is pretty flimsy at best. None of the 17,000 studies published on salt and blood pressure since 1966 has shown population wide health benefits from a low-salt diet. It is only in the last few decades that salt has received bad publicity. In fact, before the 20th century salt was a valuable commodity. Roman soldiers were even paid with it and it is the origin of the word salary.
Salt, or sodium chloride, is a naturally occurring chemical that is vital to health. It is important in the regulation of fluids and nerve conduction in the body. Usually when we eat more salt than is required by the body it is excreted in the urine. We sweat about 500mg of sodium in a 1 hour work-out. Long-term effects of cutting out salt from the diet is unknown, although it is known that even moderate reductions of salt can cause fatigue.
A 30 year study in America showed that those who ate the most salt had the fewest deaths from any cause, including heart disease. In a follow-up study it was found that reducing salt intake did reduce blood pressure slightly but increased bad cholesterol or LDL.
Obviously not content with the results so far the Second National Health and Nutrition Examination Survey ran for a further 13 years looking at data on over 7000 men and women and found that there was a 50% higher risk of heart disease if you had a daily intake of less than 6 g of salt a day. The current recommendation is that people consume no more than 6 g a day, which is equivalent to about 1 teaspoon of salt.
The lead researcher was Dr H. W Cohen, Assistant Professor of Epidemiology and Population Health at Albert Einstein College of Medicine, New York. Dr Cohen said “It is likely that there are differences between individuals with regard to sodium intake and it is clear that the data do not support the current recommendations “
In 2005 scientists across Europe completed their study involving 8000 people over 50. Their conclusions were that as long as salt intake was no more than 16 g a day it had no significant effect on blood pressure./Risk only increased with an intake over 21 g and even then it had no effect on cardiovascular problems. In fact, other scientists have gone further in saying that pregnant women with pre-eclampsia, high blood pressure, can benefit from up to 20 g of salt a day. One in 10 elderly people suffer from sodium deficiency, which can result in anxiety, hallucinations, muscle cramps and hip fractures.
The food industry perpetuates the idea that healthy food has reduced salt, encouraged by government guidelines. Only 5 to 10% of salt consumed occurs in natural foods to such as meats while more may be added during cooking or at the table. By far the greatest amount is found in processed foods with the worst ones being bred and canned vegetables.
If you are restricting your salt intake to help reduce high blood pressure, then you may wish to discuss whether this is indeed the best course of action with your GP.
Trick and Treat, How Healthy Eating Is Making Us Ill. Barry Groves. Hammersmith press Ltd 2008, p 144-156
Following further research on this topic you might like to look at a large meta-analysis of the studies here