The Swank diet is a low-saturated-fat eating plan developed specifically for people with multiple sclerosis (MS). It caps saturated fat at 15 grams per day, emphasizes fish and plant-based oils, and was designed by neurologist Roy Swank beginning in the 1950s. It remains one of the most well-known dietary approaches in the MS community, though it continues to spark debate among researchers and clinicians.
How the Diet Works
The central rule is simple: keep saturated fat at or below 15 grams per day. For context, a single fast-food cheeseburger can contain 10 to 15 grams of saturated fat on its own, so the limit is strict. Alongside that restriction, the diet calls for 4 to 10 teaspoons (20 to 50 grams) of unsaturated oils daily from sources like olive oil, flaxseed oil, and fatty fish. Unsaturated fat from nuts, seeds, and fish counts toward that oil allowance.
The theory behind this approach centers on how saturated fat affects the body’s inflammatory processes. Swank observed that MS was more common in populations with high-fat diets and hypothesized that reducing saturated fat could slow the damage to the protective coating around nerve fibers. While the exact mechanism is still debated, the broad principle of reducing inflammation through dietary fat modification aligns with what nutrition science now understands about saturated fat and immune function.
What You Can and Can’t Eat
The diet encourages white fish and shellfish, fruits and vegetables (at least four servings daily), whole grains (also at least four servings), and fat-free or very low-fat dairy products. Fish should appear on your plate at least three times per week. One egg per day is permitted, and whole wheat bread is specifically recommended over refined grains.
Red meat is heavily restricted, particularly during the first year, when it’s eliminated entirely. After that initial period, small amounts of lean red meat are sometimes reintroduced, but total saturated fat intake still can’t exceed the 15-gram ceiling. Dark-meat poultry, processed meats, full-fat cheese, butter, and most commercially baked goods are off the table because their saturated fat content makes staying under the limit nearly impossible. Any dairy you consume needs to be fat-free or close to it.
Required Supplements
The Swank diet isn’t just about food restrictions. It includes a specific supplement regimen that Swank considered essential to the plan:
- Cod liver oil: 1 teaspoon (5 grams) daily, a recommendation Swank included from his earliest publications in 1953. This provides omega-3 fatty acids along with vitamins A and D.
- Multivitamin: One capsule per day, but no more, to avoid excessive vitamin A and D intake since cod liver oil already supplies both.
- Vitamin C: 1,000 milligrams daily, recommended for its antioxidant properties.
- Vitamin E: 400 IU daily, also for antioxidant support. Both vitamin C and E help prevent the oxidation of the unsaturated fats the diet relies on so heavily.
Swank also recommended 10 to 15 grams of additional vegetable or fish oil beyond the cod liver oil, reinforcing how central healthy fats are to the plan.
The 34-Year Study
The most cited evidence for the Swank diet comes from Swank’s own long-term follow-up, published in The Lancet in 1990. He tracked 144 MS patients over 34 years, dividing them by how closely they stuck to the diet. The cutoff was 20 grams of fat per day.
Patients who adhered to the diet showed significantly less neurological deterioration and much lower death rates across all disability levels, whether they started the study with minimal, moderate, or severe disability. The most striking result was in the group that entered the study with minimal disability: when deaths from non-MS causes were excluded, 95% survived and remained physically active over the full 34-year period.
These findings are impressive but come with important caveats. The study was not randomized or controlled, meaning the people who stuck with the diet may have been healthier or more motivated in other ways. There was no comparison group eating a different structured diet. Still, the sheer length of follow-up and the size of the difference between adherent and non-adherent groups made the results hard to ignore.
How It Compares to the Wahls Protocol
The other major dietary approach in the MS world is the Wahls protocol, a modified paleo diet developed by physician Terry Wahls. The two plans share a goal of reducing MS symptoms but take very different paths to get there.
The Swank diet focuses on fat restriction, allowing grains, legumes, and fat-free dairy while severely limiting saturated fat. The Wahls protocol takes nearly the opposite approach to food groups: it eliminates all grains, legumes, eggs, and dairy (except ghee) while encouraging 6 to 9 servings of fruits and vegetables daily and 6 to 12 ounces of meat. Where Swank limits total fat, Wahls limits food categories based on an autoimmune and paleo framework. The Wahls plan also excludes nightshade vegetables (tomatoes, peppers, potatoes) during an initial elimination phase before gradually reintroducing them.
A randomized clinical trial (the WAVES trial) compared the two diets head-to-head in people with relapsing-remitting MS. Both diets reduced fatigue and improved quality of life, with no clear winner between them. This led researchers and MS organizations to suggest that the benefits may come from eating a structured, whole-foods-based diet in general rather than from one specific set of rules.
What MS Organizations Say
The National MS Society has acknowledged the evidence but stops short of endorsing the Swank diet specifically. After the WAVES trial results, Bruce Bebo, Executive Vice President of Research for the Society, called the findings “encouraging” and noted that “a healthy diet is one pathway to restoring function in people with MS.” Many MS specialists recommend that people with MS follow the same low-fat, high-fiber guidelines promoted by the American Heart Association and American Cancer Society for the general population, rather than prescribing the Swank diet in particular.
This middle-ground position reflects the reality that while the Swank diet’s principles are broadly consistent with healthy eating, the strongest evidence for it comes from observational rather than randomized research. For people with MS who want a structured plan with decades of real-world use behind it, the Swank diet remains a reasonable and well-documented option. Its emphasis on low saturated fat, omega-3 supplementation, and whole foods aligns with mainstream nutrition advice, even if the specific gram-level restrictions go further than standard dietary guidelines require.