Nutrition impacts our health in multiple ways, and the current epidemic of obesity and diabetes provide direct, overwhelming proof of how poor nutrition can precipitate disease.
Not surprisingly, research is showing that dietary habits and lifestyle also influence the course of neurological conditions such as multiple sclerosis (MS), where other environmental and genetic factors seem to bear more weight (1, 2).
MS is a potentially disabling condition in which nerve fibers progressively lose the protective myelin sheath that surrounds them. This results in weakness, decreased motor coordination, impaired mobility and ambulation, and fatigue. While the exact causes are unknown, epidemiologic evidence points to a combination of autoimmune mechanisms, genetic factors, and lifetime environmental exposures associated with infections and inflammatory reactions. Nutrition has been signaled as a possible co-factor in MS by influencing the inflammatory cascade and changes in the gut microbiota (3, 4).
While basic research continues to unveil the molecular events that underlie MS, the potential benefits of dietary interventions are also being explored with the goal of improving the quality of life of people with MS.
How Can Nutrition Improve Function in Multiple Sclerosis?
A recent 2019 study appearing in The International Journal of MS Care and conducted by physical therapists at The State University of New York at Buffalo evaluated the associations between nutrition and ambulation, daily activity, quality of life (QOL), and fatigue in MS patients with mild-to-moderate disability (5).
The study included 20 individuals (14 women and 6 men; mean age: 57.9 years) with a mean time since MS diagnosis of 18.4 (range, 3–39) years. They presented a mean Expanded Disability Status Scale (EDSS) score of 4.1 (range 1.5-6.0), denoting mild-to-moderate disability. Eligible patients had no diabetes, inflammatory bowel disease, or dysphagia, and had not experienced active disease relapse within the past 30 days. All the outcome measures were collected on 2 different days separated by a minimum of 1 week.
Functional tests included:
- 6-Minute Walk Test (6MWT). It measures the distance that patients can cover within 6 minutes by walking as fast as they safely could.
- Timed 25-Foot Walk Test (T25FW). It measures the time it takes participants to “walk as quickly as possible but safely” to cover a distance of 25 ft.
- TUG Test. It measures the time it takes participants to rise from a chair at the word “go,” walk as quickly as possible but safely to a mark 10 ft away, turn around, walk back, and sit down again.
- Physical activity (mobility and energy expenditure) was measured using an accelerometer worn over the dominant hip for 7 days.
- Body Fat Percentage was calculated from bioelectrical impedance measurements on a segmental body composition monitor.
- 36-item Short Form Health Survey (SF-36): The self-administered SF-36 survey measures Quality of Life using eight subscales: physical functioning, role limitations due to physical problems, bodily pain, general health perceptions, vitality, social functioning, role limitations due to emotional problems, and mental health.
- 12-Item Multiple Sclerosis Walking Scale (MSWS-12). This self-report scale assesses patients perceptions of their walking ability during the previous 2 weeks.
- Modified Fatigue Impact Scale. This self-report survey measures the impact of fatigue on a patient’s daily life in terms of physical, cognitive, and psychosocial functioning.
Items 5 to 8 (biometric data and self-reports) were assessed on day 1 of the study, and items 1 to 4 (physical tests) on day 2. Potential associations between nutrient intake and physical/functioning outcomes were assessed by cross-analyzing responses to the tests above with two dietary assessments delivered on day 1 and returned by patients on study day 2:
- Three-Day Food Diary (3-DFD). Respondents were asked to record the type and amount of consumed products, dishes, and beverages at the time of consumption on 3 consecutive days (including 1 weekend day). To standardize reporting, participants were given specific instructions on how to appropriately record food and portion size.
- Food Frequency Questionnaire (FFQ). The FFQ collects information about food consumption over a specified period of time. Participants were asked to quantify the frequency (daily, monthly, yearly) of their intake over the past 12 months using standardized serving sizes of 116 food items
The overall analysis showed that consuming more fats than carbs was associated with improved physical performance and QOL in people with mild-to-moderate MS; in contrast, consuming high carb diets had a negative impact. Also, in line with previous research, the 3-DFD revealed that ingestion of cholesterol and some micronutrients (iron, magnesium, and folate) correlated with better ambulation, daily function, and QOL in both the SF-36 and during functional tests (6).
The finding that diets with higher fat contents may help MS patients perform better physically somewhat conflicts with previous reports. Swank and Goodwin, for instance, reported in 2003 on 150 MS patients who followed a low-fat diet for over 30 years, concluding that diets low in fats were associated with reduced disease progression and mortality (7). Newer studies, however, also stress the benefits of reduced carbohydrate intake for MS.
Weighing down this controversy is the shift in dietary patterns that started about 20 years ago in the US. Namely, the substitution of fats (blamed for increased rates of inflammatory conditions, cardiovascular disease, and obesity) by carbs. As a consequence, the current US food pyramid consists of 50% carbs, a change that resulted in increased rates of inflammatory conditions, cardiovascular disease, and obesity.
So would MS patients be better off by largely avoiding fats, or carbs? The answer of course is no. As Harvard’s Nutrition Source points out “Cutting back on saturated fat will likely have no benefit, however, if people replace saturated fat with refined carbohydrates.”
High Fat, Low Fat, High Carb, Low Carb or Somewhere in the Middle?
To understand this issue, let’s briefly examine the mechanisms underlying the health effects of fats and carbs. There are clear distinctions within food types.
Saturated lipids (like meat fats, and trans fats from hydrogenated oils used to make margarines, frozen foods, chocolates, etc.) are solid at room temperature, are harder for our bodies to break down, and were shown to reduce the ability of cells to sense insulin and contribute to obesity, atherosclerosis, and coronary disease (although there is some controversy); in contrast, unsaturated (mono- and poly-unsaturated) lipids contained in olive oil, avocado, and nuts, are a mainstay of the Mediterranean diet and were shown to help control blood glucose levels and regulate blood pressure, among other health benefits (8, 9).
And something similar happens with carbohydrates. Simple carbs are sugar molecules (mono- or disaccharides), like glucose, fructose, and sucrose that are obtained by refinement of more complex foods (wheat, sugar cane, corn). They provide fast but short-lasted energy, and promptly stimulate insulin release to normalize their surging blood levels. Fast insulin peaks, however, quickly reduce blood glucose and triggers the release of hunger hormones, which may lead to overeating. Over multiple, continuous cycles, insulin secretion in the pancreas may become impaired and cells may also begin to fail to respond to it (insulin resistance). In both cases the excess glucose keeps stressing cells and tissues, leading eventually to chronic inflammation, metabolic dysfunction, and disease. Interestingly, studies show that decreased insulin sensitivity with postprandial hyperinsulinemia prevail in newly diagnosed, untreated MS patients with a low EDSS score, contributing to disability (10, 11).
In contrast, complex carbs (present in fruits, vegetables, whole rice, and grains) are made of long chains of sugar molecules (polysaccharides) chained together. These are broken down more slowly by our bodies, leading to a gradual rise in blood sugar, and a gentler and more sustained rise in insulin levels. Glycemic control is thus more easily achieved, reducing the risk of cellular stress. Diets rich in complex carbs and low in refined carbs, like the Mediterranean diet, were associated with both reduced odds of developing MS, and lower risk of cardiovascular disease in people with MS (12, 13).
When diets high in both saturated fats and refined sugars (simple carbs) combine, the usual consequence is obesity, which raises the risk for insulin resistance, metabolic syndrome (characterized by hyperglycemia, hyperlipidemia, high blood pressure, and elevated cholesterol), diabetes, and cardiovascular disease (14). Both childhood obesity, especially in girls, and type 2 diabetes have been associated with increased risk of developing MS (15, 16).
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Nutrition and MS: What Does the Evidence Show?
The energy that our cells derive from simple carbs is depleted fast, and this results in fatigue, decreased functional performance, and reduced physical activity. Conversely, free fatty acids provide longer-lasting energy output and reduce insulin responses. This may partly explain why increased fat, and not carbohydrate, consumption was associated with better ambulation and QOL in people with MS (5).
Based on these perceived benefits, the ketogenic diet has gained popularity among people with MS; this diet includes high-fat (~75%), low-carbohydrate (~5%), moderate protein (~20%), reduces the reliance on glucose for energy needs and has shown to be beneficial in other neurological conditions such as epilepsy, Alzheimer’s and Parkinson’s disease. More research is needed, however, to confirm its benefits in patients with MS (17).
Other dietary approaches that variously aim at controlling fat, carb, and micronutrient intake have shown to provide some benefits to people with MS (18, 19). These include the original low-fat Swanks diet and the newer Wahls diet. The latter, also known as the Autoimmune Protocol (AIP), is a modified version of the Paleo diet that allows healthy meats, including organ meats, seafood, most vegetables, fruits, fats, and fermented foods, and excludes grains and gluten, eggs, nuts, seeds, and nightshade vegetables (tomatoes, potatoes, eggplant, peppers). A recent study suggested that the AIP is a promising complementary strategy in the management of MS (20).
With different approaches available, defining the best dietary intervention for MS would require attention to each patient’s condition and specific nutritional deficits and needs. An upcoming clinical trial comparing the low saturated fat (Swank) and the modified Paleolithic (Wahls™) diets in their ability to improve symptoms and QOL in people with MS should provide renewed insight into best nutrition practices to manage MS (21).
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