Findings from just over 175,000 nurses proved inconclusive as the team could not find no link between the minerals potassium, magnesium, calcium, phosphorus, iron, zinc, manganese, copper and MS risk.
“Higher intake of vitamin D has been associated with a lower risk of MS, but our findings show that intake of minerals is not an important determinant of MS risk," said study author Dr Marianna Cortese, from the Harvard T.H. Chan School of Public Health based in Boston.
The progression of MS and its link to nutrition is a source of extreme interest amongst doctors, nutritionists and dietitians.
As well as a contributing factor, diet may have a role as a complementary treatment to manage the disease’s progression with a low-fat diet and polyunsaturated fatty acid (PUFA) supplementation often mentioned.
What has received increased attention is the role of minerals, trace elements, antioxidants, and vitamins with one study pointing to an increased risk of MS with vitamin D insufficiency.
While increased levels of vitamin D may slow disease progression, it is unclear whether dietary antioxidants have additional biological roles extending beyond simple antioxidant activity in MS.
Writing in the journal Neurology, the study enrolled 80,920 female nurses in the Nurses' Health Study and 94,511 in the Nurses' Health Study II.
The nurses were quizzed about their diet as well as their supplement use using a questionnaire that was carried out every four years. This continued for up to 20 years of follow-up before 479 of the women developed MS.
Adjusting for age, ancestry, body mass index at age 18, supplemental vitamin D, smoking, and total energy intake, the research team could find no relationship between mineral intake and a higher or lower risk of MS.
The team also found no association between mineral intake at the beginning of the study and also cumulative intake before MS onset.
"While previous studies have suggested that zinc levels are lower in people with MS and that zinc may produce a more anti-inflammatory immune response in an animal model of MS, these effects may be too subtle within the range of zinc intakes common in the US population to modify MS risk," Dr Cortese said.
In discussions about the study’s limitations, the team said only women were included in the sample group. Most of the women were Caucasian, so the results could not be directly generalized to men or people of other races.
Diet still significant
Commenting on the findings, the National Multiple Sclerosis Society, which supported the study, said that whilst it does not support the idea that mineral intake influences a person’s chance of getting MS, it also does not imply that diet has no bearing on a person’s experience living with MS.
“Maintenance of general good health is very important for people with any chronic disorder,” the Society said.
“What and how you eat can make a difference in your energy level, bladder and bowel function, and overall health.”
Published online: DOI: 10.1212/WNL.0000000000006800
“Total intake of different minerals and the risk of multiple sclerosis.”
Authors: Marianna Cortese, Tanuja Chitnis, Alberto Ascherio, Kassandra L. Munger.