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Does salt really affect blood pressure?

The Bottom Line

  • High blood pressure increases the risk for heart attacks and strokes.
  • Most people consume too much salt, which contributes to high blood pressure.
  • Studies show that reducing salt intake for at least four weeks can significantly lower blood pressure and the risk of heart disease.

We are bombarded with so much information from various sources that often we hear conflicting reports about what is best for our health and well-being. It can be confusing and it can cause us to doubt everything we read, hear or ever believed!

For example, for years we’ve been told to watch our salt intake to avoid high blood pressure, a worrisome condition as it puts us at greater risk for heart attacks and strokes.(1) But is cutting back on salt going to make enough of a difference? And can consuming too little salt cause other problems?

That has been the focus of numerous research studies, including 34 randomized controlled trials that were included in a systematic review (2) The studies involved more than 3,200 people between the ages of 22 and 73. Two thirds had high blood pressure; the rest had normal blood pressure. The average reduction in salt intake was 4,400 mg per day over a minimum of four weeks.

Adults require no more than 1,500 mg of of salt per day for optimal body function and the maximum recommended daily intake is 2,300 mg, but most people consume much more: the pre-study salt intake for the participants was 7,300 to 11,700 mg – the equivalent of three to five teaspoons of salt.

What the research tells us

We are right to cut back! The evidence was strong that reducing salt intake lowers blood pressure in adults, regardless of sex or ethnicity and without any adverse effects. Improvements were greatest in people with high blood pressure (systolic blood pressure decreased an average of 5.39 mm Hg and diastolic blood pressure decreased an average of 2.82 mm Hg) but notable drops were also seen in people with normal blood pressure.

The research also suggests that greater reductions in salt intake will likely decrease blood pressure even further. As a result several developed countries are revising their recommended targets and adopting policies to reduce salt intake.(3)

So if reducing our salt intake is a prudent course of action and one that will significantly lower our risk of heart disease and stroke, what’s the best way to do it? A less liberal use of the salt shaker will help. But the real culprit, accounting for up to 85% of our salt consumption, is processed foods. A few sausage links or slices of bacon can account for more than half your daily salt limit. Canned foods, cheeses, breads, cereals, sauces and pickles are among the many other foods that are high in sodium. It is further support for a diet high in whole, natural and fresh food.


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References

  1. Lewington S, Clarke R, Qizilbash N, et al. Age-specific relevance of usual blood pressure to vascular mortality: A meta-analysis of individual data for one million adults in 61 prospective studies. Lancet. 2002;360:1903-13.
  2. He F, Jiafu L, MacGregor G. Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomized trials. BMJ. 2013;346:1325.
  3. National Institute for Health and Clinical Excellence. Guidance on the prevention of cardiovascular disease at the population level [Internet]. NICE; 2010. Available at: http://guidance.nice.org.uk/PH25

DISCLAIMER: The blogs are provided for informational purposes only. They are not a substitute for advice from your own healthcare professionals.

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