People who consume unprocessed red meat as part of a healthy Mediterranean diet may reduce their risk of multiple sclerosis (MS), new research led by Curtin University and The Australian National University has found.
The research, published in The Journal of Nutrition, examined data from 840 Australians who took part in the Ausimmune Study to determine whether there was a link between consuming a Mediterranean diet that includes unprocessed red meat, such as lamb, beef and pork, and a reduced risk of a first episode of CNS demyelination, a common precursor to MS.
Lead author Dr. Lucinda Black, from the School of Public Health at Curtin University who completed the research as part of her MSWA Postdoctoral Fellowship, said the number of people being diagnosed with MS was increasing globally, suggesting that environmental factors such as low sun exposure, low vitamin D, and poor diet may be contributing factors.
“Previous research suggests that a Mediterranean diet can help to reduce the risk of certain health issues, including cardiovascular diseases, diabetes, cancer, Alzheimer’s disease and dementia and improve overall life expectancy.
However, there is inconclusive evidence to suggest a Mediterranean diet also reduces the risk of developing MS,” Dr. Black said.
“It is unclear why consuming red meat combined with a healthy diet may lower the risk of MS, but red meat contains important macro and micronutrients including protein, iron, zinc, selenium, potassium, vitamin D, and a range of B-vitamins, many of which are important for healthy neurological function.”
To ensure that the risks do not outweigh the benefits, Cancer Council WA recommends eating only a moderate amount of unprocessed lean red meat, which equates to no more than one daily serving, where a serving is 65 grams of cooked meat.
Co-author Professor Robyn Lucas, from The Australian National University in Canberra, said the research highlighted the importance of educating people who are at a higher risk of MS about the impact of their diet and other environmental factors.
“We know very little about how people can reduce their risk of developing MS, but previous research has shown that not smoking and ensuring people get sufficient sun exposure to maintain adequate vitamin D levels may contribute to this,” Professor Lucas said.
“This new work provides valuable information on another way that people at high risk of MS might reduce that risk, which includes eating a healthy, Mediterranean diet that includes moderate amounts of unprocessed red meat.”
The Ausimmune Study, funded by the National Multiple Sclerosis Society of the United States of America, the National Health and Medical Research Council of Australia, and Multiple Sclerosis Research Australia, was conducted during 2003 and 2006 in four regions of Australia, including Brisbane, Newcastle, western Victoria, and Tasmania.
The study investigated the link between environmental risk factors and early symptoms of MS.
The evidence associating red meat consumption and risk of multiple sclerosis is inconclusive.
We tested associations between red meat consumption and risk of a first clinical diagnosis of central nervous system demyelination (FCD), often presaging a diagnosis of multiple sclerosis.
We used food frequency questionnaire data from the 2003–2006 Ausimmune Study, an incident, matched, case-control study examining environmental risk factors for FCD.
We calculated non-processed and processed red meat density (g/1,000 kcal/day). Conditional logistic regression models (with participants matched on age, sex, and study region) were used to estimate odds ratios (ORs), 95% confidence intervals (95% CI) and p-values for associations between non-processed (n = 689, 250 cases, 439 controls) and processed (n = 683, 248 cases, 435 controls) red meat density and risk of FCD.
Models were adjusted for history of infectious mononucleosis, serum 25-hydroxyvitamin D concentrations, smoking, race, education, body mass index and dietary misreporting.
A one standard deviation increase in non-processed red meat density (22 g/1,000 kcal/day) was associated with a 19% reduced risk of FCD (AOR = 0.81; 95%CI 0.68, 0.97; p = 0.02).
When stratified by sex, higher non-processed red meat density (per 22 g/1,000 kcal/day) was associated with a 26% reduced risk of FCD in females (n = 519; AOR = 0.74; 95%CI 0.60, 0.92; p = 0.01).
There was no statistically significant association between non-processed red meat density and risk of FCD in males (n = 170). We found no statistically significant association between processed red meat density and risk of FCD.
Further investigation is warranted to understand the important components of a diet that includes non-processed red meat for lower FCD risk.
Diet is potentially a modifiable risk factor for multiple sclerosis (MS); however, the current evidence in inconclusive.
The literature is somewhat consistent for higher intake of fish and very long-chain omega-3 polyunsaturated fatty acids (VLCn3PUFA: eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid) and reduced risk of MS (1–4) Studies investigating red meat consumption and risk of MS have returned inconclusive results (4–10).
Non-processed red meat is an important dietary source of protein, iron, zinc, vitamin B12, other minerals and vitamins, and VLCn3PUFA (11).
However, epidemiological studies have linked higher red meat consumption with an increased risk of various chronic diseases, including obesity, type 2 diabetes, cardiovascular diseases and cancers.
The findings have been attributed largely to the fat content of red meat, and the possible formation of carcinogenic compounds by cooking at high temperatures (12).
It has also been postulated that long-term ingestion of N-glycolylneuraminic acid from consumption of red meat may promote inflammation and cancer progression (13), and may be a risk factor for MS (14).
The strongest evidence around red meat consumption and chronic diseases is for higher processed meat intake and increased risk of colorectal cancer (15) and all-cause mortality (16); similar associations with other cancers have also been observed (17).
The 2003–2006 Australian Multi-center Study of Environment and Immune Function (Ausimmune Study) was a multi-center, case-control study examining associations between environmental factors and risk of a first clinical diagnosis of CNS demyelination (FCD) (18).
Given that many people change their diet when diagnosed with MS (19, 20), associating dietary factors with risk of FCD offers the best opportunity to assess dietary risk factors before disease-related changes in behavior occur.
We recently showed that a higher healthy dietary pattern score (high in poultry, fish, eggs, vegetables, and legumes) was associated with reduced risk of FCD in the Ausimmune Study (21).
Also in the Ausimmune Study, there was no evidence that saturated or total fat intake in the preceding 12 months was associated with an altered risk of FCD (2); however, fat intake was from all dietary sources, and meat consumption was not specifically investigated.
To better understand the relationship between meat consumption and risk of MS, we examined associations between red meat consumption (non-processed and processed) and risk of FCD in the Ausimmune Study.
More information: Lucinda J Black et al. A Higher Mediterranean Diet Score, Including Unprocessed Red Meat, Is Associated with Reduced Risk of Central Nervous System Demyelination in a Case-Control Study of Australian Adults, The Journal of Nutrition (2019). DOI: 10.1093/jn/nxz089
Journal information: Journal of Nutrition
Provided by Curtin University