A study 
published in the journal BMJ Open shows diets high in salty foods are a major culprit in headaches and that reducing salt can bring relief.
Nearly 400 people participated in the study, and those who ate foods high in sodum (8 grams a day, or about 1.5 tsp.) had nearly one-third more headaches than people who ate foods low in sodium (about 4 grams a day). The highest occurrence of headache was reported by participants eating a typical North American diet with high sodium (47%), and the lowest occurrence was reported by participants on the DASH diet with low sodium (36%). The DASH diet, which many know as a diet to help control blood pressure, is low in fat and rich in fruits and vegetables.
Regardless of which diets the participants followed, researchers found that those who ate the most sodium reported the highest frequency of headaches, and those who ate the least sodium reported the least amount of headaches.
“A reduced sodium intake was associated with a significantly lower risk of headache, while dietary patterns had no effect on the risk of headache in adults,” said Lawrence Appel, MD, MPH, of Johns Hopkins University. “Reduced dietary sodium intake offers a novel approach to prevent headaches.”
While high blood pressure is often associated with high salt intake and headache, the researchers found that people with normal blood pressure had fewer headaches when they reduced salt intake. They noted that a process that is independent of blood pressure may mediate the relationship between sodium and headaches.
The researchers added that the data on the relationship between sodium intake and any form of headaches are sparse, and more study is needed to replicate their findings and further explore the link between sodium intake and headache.
National Headache Foundation Newsletter
January, 2015
Greetings,
I read your article with great interest and disappointment at the same time. Salt does not function in the body alone but in a precisely choreographed ionic balance with potassium, glucose, and water among various other substances like calcium and magnesium and many more. When in a clinical trial a single substance that for a critical part of the body’s electrolyte is tested in a vacuum, as in this clinical trial, the results will be erroneous. Research without consideration of the other ions that participate in electrolyte balance–and therefore affect migraine–is misleading. I hope some day research incorporating all variables will be conducted. In particular glucose control when examining how salt behaves.
The reason for this is that eating sugar (part of which is glucose) removes water and salt from cells causing edema. Thus people coming to the research lab for their clinical trial may be in various states of edema prior to the salt experiment. Furthermore, a very important balancing factor of salt in electrolyte is potassium. If potassium and salt (sodium and chloride in ionic form) are out of balance as a result of the increased salt, migraine will occur. If salt then is reduced, balance between potassium and sodium can be regained and migraine will lessen.
Thus taking salt alone and using that as a single point of coming to a conclusion is misleading and is harmful.
Sincerely,
Angela A. Stanton, Ph.D.