The study assigned 390 people to one of three diets, with high, medium or low salt content – defined as eight, six or four grams of salt per day – over a 30-day period. They returned to the trial centre three times to try all three diets in random order. They also ate according to one of two dietary patterns; either the DASH (Dietary Approaches to Stop Hypertension) diet, rich in fruit, vegetables and low-fat dairy, or a control diet, described as a typical western diet.
The researchers found that when asked about a range of side effects, those on the lowest salt diet reported 31% fewer headaches than those on the highest salt diet. However, they found no difference in headache occurrence between the different dietary patterns. The effect was also independent of blood pressure, with lower headache occurrence reported by those with high and normal blood pressure.
“Our results contrast with the popular belief that a diet rich in fruits, vegetables and potassium and low in saturated and total fat may ease the frequency, or even prevent, headache,” the study’s authors wrote.
“…The results of this study provide encouraging evidence in support of dietary recommendations to lower sodium intake: recommendations which are currently based on the relationship of sodium intake with blood pressure.”
Salt reduction campaigning group Consensus Action on Salt and Health (CASH) welcomed the findings.
“We have long suspected that reducing salt intakes reduces the number of people developing headaches, but this is the first well-controlled trial that really demonstrates a very large reduction in headaches just from modest reductions in salt intake,” CASH chair Graham MacGregor said in a statement.
“Importantly, the effect is independent of the level of blood pressure, as the reduction in headaches occurred in those with high and normal blood pressure. We would strongly advocate that those people who have headaches reduce their salt intake as it may abolish their headaches as well as having the very important effect of lowering their blood pressure and thereby the risk of a stroke and or heart attack.”
Source: BMJ Open
“Effects of dietary sodium and the DASH diet on the occurrence of headaches: results from randomised multicentre DASH-Sodium clinical trial”
Authors: Muhammad Amer, Mark Woodward, Lawrence J Appel.