For over fifty years, people have suggested a role for diet in the treatment of MS. Many health care professionals are not knowledgeable in this area and diet advocates may exaggerate their claims. This has created a field that has long been clouded with confusion and surrounded by controversy.
The Importance of A Well Balanced Diet
Before delving too deeply into the specifics of certain diets related to MS, it is important to understand the basic components of a healthy diet, which is one in which a variety of foods is consumed. In 2005, the U.S. Department of Agriculture (USDA) replaced its well-known generalized food pyramid, with MyPyramid (www.mypyramid.gov). MyPyramid takes an individual’s sex, age, and physical activity into account when providing personalized recommendations for the intake of grains, fruits, vegetables, meat/beans, dairy, and oils.
Two Treatments versus One Treatment
Fatty-acid supplements and diets may affect MS through immune system interactions. Many conventional medications for MS are used because of their effects on the immune system. These medications include Avonex, Betaseron, Copaxone, Novantrone, Rebif, and Tysabri. Using both diet and conventional medications to regulate the immune system may be beneficial, but this has not been adequately studied. Furthermore, immune system regulation is not well understood and the possibility of harmful drug-diet interactions cannot be completely dismissed, although it does seem unlikely.
Based on the current evidence, people with MS are much more likely to benefit from conventional medicine than a dietary approach. This should be taken into consideration if only one treatment approach is chosen.
Fat is used in the body to produce energy and provide the building blocks for the membranes of all cells in the body. Stored in fatty tissue, fats are made up of fatty acids, which are chains of carbon atoms with hydrogen and oxygen atoms attached. Fats that will not allow any more hydrogen atoms to attach are called saturated fats. These fats, which are solid at room temperature, are found in high amounts in butter, hard cheese, and red meat. When the carbon chains have less than the maximum number of hydrogen atoms they are called unsaturated fats. These fats are liquid at room temperature and can be found in high amounts fish oils, seed oils, and vegetable oils.
Unsaturated fats can be either mono- or polyunsaturated. Monounsaturated fatty acids have only one place for hydrogen atoms to attach. This type of fatty acid is prevalent in olive oil. Polyunsaturated fatty acids, or essential fatty acids, have more than one place for hydrogen atoms to attach and can not be synthesized by the human body.
There are two important types of polyunsaturated fatty acids, omega-six and omega-three fatty acids. Both types are named for their chemical structure.
Several different omega-six fatty acids exist; a pathway of biochemical reactions is responsible for converting between these fatty acids. Omega-six fatty acids include linoleic acid, gamma-linolenic acid (GLA), and dihomo-gamma-linolenic acid. These acids are eventually converted to prostaglandins and other important immune system-regulating compounds.
Omega-three fatty acids include alpha-linolenic acid, eicosapentanoic acid (EPA), and docosahexanoic. The most well known source of these fatty acids is seafood, especially fish. The body can converts omega-three fatty acids into leukotrienes and prostaglandins, similar to the end products of the omega-six pathway.
Polyunsaturated Fatty Acids and MS
Most of the dietary studies in MS have involved polyunsaturated fats. Research studies in the 1950s suggested that the incidence of MS was higher in areas that consumed more saturated fats (animal fat) and lower in areas where there was a greater intake of polyunsaturated fats (fish and vegetable oils).
As a result of these studies, work was done to determine the levels of polyunsaturated fats in people with MS. Some of these studies, although not all, reported decreased levels of polyunsaturated fatty acids. Omega-six fatty acids, such as linoleic acid, were the most significantly decreased. A decrease in omega-three fatty acids was noted in only a few of these studies.
It has been suggested that people with MS either do not consume enough polyunsaturated fats or may have an abnormality in the biochemical processes that regulate them. In the 1950s, it was suggested that people with MS might have a thickening of the blood, producing “sludges”. This idea has since been dismissed. Polyunsaturated fatty acids are a major component of the nerve-insulating material myelin. It has been proposed that a lack of polyunsaturated fatty acids could cause the myelin abnormalities that are seen in MS. Current theories focus on the last steps in both chemical pathways, where the fatty acids are converted into immune-suppressing compounds. A lack of these compounds may lead to an excessively active immune system, as is seen in MS.
Fats and Other Medical Conditions
Diets with high amounts of saturated fats have been found to have negative impacts on health. Saturated fat, especially from meat, is known to increase cholesterol, which can lead to cardiovascular conditions, such as stroke and heart disease. High intake of saturated fats has also been associated with some types of cancer and hypertension. Diets with less saturated fats and more polyunsaturated fats have many health benefits beyond the possible implications for MS.
The Swank Diet
Dr. Roy Swank authored some of the original work on dietary fat and MS. In 1948, he started treating people with MS with a low saturated fat, high polyunsaturated fatty acid diet. His diet was very strict, decreasing saturated fat intake to 15 grams per day. Red meat is completely prohibited for the first 12 months, and after that only three ounces are allowed per week. Processed foods that contain saturated fats and high-fat dairy products are not permitted. A large amount of polyunsaturated fatty acids are recommended, which is achieved in part through frequently eating fish and taking cod liver oil supplements. Dr. Swank also recommended taking a multivitamin.
The results reported by Dr. Swank were impressive. He published on his longitudinal study three times over the course of the 50 years. The study began with 144 participants with MS. Those on the Swank diet reportedly had less frequent and less severe attacks, reduced overall impairment, and decreased death rate. Better outcomes in his studies were associated with earlier treatment. Dr. Swank reported a 95 percent decrease in frequency of attacks. Later publications included a much smaller subgroup of the original 144, and lacked documentation of the results of standard neurological tests.
Dr. Swank’s clinical trial lacks many of the standard criteria that are now expected in clinical trials. Specifically, it was not randomized, blinded, or placebo-controlled.
The Swank diet is very strict. It is important that people who follow the diet ensure adequate protein intake, due to decreased meat consumption.
Dr. Swank and Barbara Dugan co-authored The Multiple Sclerosis Diet Book. This book has more information, about the diet, the clinical trial, and recipes that conform to the diet.
Other Low-Fat Diets
No clinical studies have compared the Swank diet to other low-fat diets. Dietary approaches that reduce saturated fat intake, increase polyunsaturated fatty acid intake, increase fiber intake, and create a well-balanced diet may be more practical. It is important to consume a wide variety of foods, several servings of fruits and vegetable daily, and eat whole grain cereals and breads. Saturated fat should be limited, and overall consumption of fat should be no more than 30 percent of total calorie intake. Fish is recommended two to three times per week. Salt, sugar, and alcohol should be used in moderation. These guidelines are generally easier to follow than the Swank diet and may have beneficial or preventative effects on MS, stroke, heart disease, and other conditions.
Supplements of Polyunsaturated Fatty Acids
Dietary changes can increase polyunsaturated fats in the body. It is also possible to increase intake through the use of supplements, some of which have been examined in clinical trials.
Omega-Six Polyunsaturated Fatty Acids
Studies of Linoleic Acid.
The are many MS-related studies of linoleic acid supplementation. In an animal model of MS, deficiencies in linoleic acid appear to be harmful, while supplements have proved beneficial.
In the 1970s, three randomized, blinded, placebo-controlled studies of linoleic acid supplementation were completed in people with MS. In all three studies, sunflower seed oil was used. One study reported no benefit from treatment. The other two noted significant decreases in the severity and duration of the attacks, while frequency and overall progression of disability remained unchanged.
When the data from the three studies were pooled together and analyzed in 1984, several findings were reported. The three studies combined provided data on 172 subjects. It was reported that people with little or no disability at the start of treatment had a slowed progression of MS. Linoleic acid was associated with decreased duration and severity of attacks, regardless of the severity of the disease when treatment began. Some of the statistical methods employed when analyzing the pooled data have been questioned.
The data concerning the beneficial effects of linoleic acid on MS are suggestive but not definitive.
Sources of Linoleic Acid.
Seeds and nuts, and oils from seeds and nuts, are high in linoleic acid. These include safflower seed oil, sesame seed oil, and sunflower seed oil. Flaxseed oil, also known as linseed oil, has linoleic acid as well as omega-three fatty acids.
By consuming more of these foods in the diet, including oils, one can increase linoleic acid intake. Oil supplements are another, more aggressive method. The ideal dosage of linoleic acid has not been determined, nor has the optimal ratio of omega-six to omega-three fatty acids. The dosage that is sometimes recommended is four teaspoons of oils containing linoleic acid. These oils should be stored in cool, dark places and should not be heated before consumption. Many people enjoy them on salads or mixed in with vegetables or dairy products.
Risks of Linoleic Acid.
There is a concern that linoleic acid supplementation may increase the risk of some cancers. Although this issue is not fully resolved, a 1998 review evaluating all research on linoleic acid supplementation found it unlikely that there was an increased risk of cancer.
Linoleic acid supplementation can also produce several other side effects. These may include an unpleasant oily taste, diarrhea, and increased triglyceride levels in certain people. Polyunsaturated fatty acids may also produce a deficiency in vitamin E, which may be avoided through supplementation with low doses of vitamin E.
Omega-Three Fatty Acids
In 1989, a large-scale study of omega-three fatty acid supplementation with fish oil in MS was completed. The results of the study showed a trend towards improvement in the treatment group, but this trend was not statistically significant.
Another, smaller study combined supplements with glatiramer acetate (Copaxone) or interferons (Rebif, Betaseron, Avonex). Conventional MS medications and low-fat diets were combined with either olive oil intake or fish oil intake. Emotional and physical functioning in the fish oil group trended towards improvement, although the trend was not statistically significant. Both groups benefited from a decrease in attack rates.
Other immune diseases have seen benefits from omega-three fatty acid supplements. In rheumatoid arthritis, omega-three fatty acids may decrease joint swelling and stiffness.
Omega-three fatty acids may also have the potential to prevent or treat heart disease, as they mildly decrease blood pressure and triglycerides levels.
Sources of Omega-Three Fatty Acids.
Fish and other seafood are amongst the most common food sources of omega-three fatty acids. Fatty fish, such as salmon, Atlantic mackerel, Atlantic herring, sardine, bluefin tuna, and cod liver, are especially good sources of omega-three fatty acids. It is sometimes recommended that two or three servings of fish be consumed weekly.
It is also possible to consume omega-three fatty acids in supplements. As with omega-six fatty acids, the optimal dose is not known, nor is the appropriate ratio of omega-six to omega-three fatty acids.
Omega-three fatty acids are available as supplements. Both fish oil and cod liver oil are available in liquid form or in capsules. It is also possible to buy concentrated EPA and DHA. It is believed that doses of three grams or less a day are safe.
Risks of Omega-Three Fatty Acids.
Consumption of large amounts of fish raises about mercury toxicity. Women who are pregnant or may become pregnant should be especially wary of excessive fish intake. Relatively high levels of mercury are found in shark, king mackerel, and swordfish. Mercury contamination does not appear to be an issue with fish oil supplements.
The U.S. Food and Drug Administration (FDA) determined fish oil supplements to be safe when doses of DHA and EPA were kept below 3 grams daily. One seven-year study found no adverse effects associated with long-term use of fish oil.
Cod-liver and flaxseed oil have unpleasant tastes, which can be mitigated by cooling. Intake of more than 45 grams of flaxseed oil a day can have a laxative effect.
Omega-three fatty acids can produce vitamin E deficiency. As a result, supplemental vitamin E may be indicated. Although fish oil products do not usually contain vitamin A, shark, halibut, and cod-liver oils may contain large amounts of vitamin A. High levels of vitamin A can be toxic, especially for women who are pregnant. As a result, excessive intake of these oils should be avoided.
In people who are aspirin-sensitive, omega-three fatty-acid supplements can impair lung function. People with diabetes may experience increases in blood sugar levels. In people with manic-depressive illness and depression, these supplements may produce hypomania, a condition characterized by excessive mental and physical activity. The safety of these supplements for women who are pregnant or breast-feeding has not been established.
Fish oils, especially EPA, may interfere with blood-clotting and thus should be avoided by people with blood-clotting disorders, people who are taking blood-thinning medications (including high doses of aspirin), and those who are undergoing surgery.
Vitamin E and Polyunsaturated Fatty Acids
It is important to note that polyunsaturated fats may decrease levels of vitamin E in the body. If large quantities of polyunsaturated fat are taken, vitamin E intake must be increased. High doses are not necessary—in fact, as an antioxidant, they may even have negative consequences for people with MS. Many suggest that 0.6 to 0.9 international units (IU) of vitamin E be consumed for every gram of polyunsaturated fatty acid.
Different Interpretations of Information
Diets and fatty-acid supplements in MS is a controversial topic. The work is far from definitive, but some studies suggest a possible benefit.
There is much controversy over the role of diet in multiple sclerosis, which often leads to confusion for people with MS. It is unlikely that there is a single correct approach to diet.
- – The mainstream standpoint, which is relatively conservative, is that the results are not conclusive and more research needs to be done before specific recommendations can be made.
- – A less conventional approach is that these diets and supplements are not likely to be harmful and may be beneficial. The data are not definitive, but some suggestive data support this perspective. A moderate course of action would include a low saturated fat, high polyunsaturated fat, well-balanced diet (as outlined above) and certain supplements. Supplements for omega-six fatty acids could include moderate amounts of sunflower seed oil or evening primrose oil. Modest amounts of omega-three fatty acid supplements, such as fish oil, could be considered. As noted, modest doses of vitamin E may be appropriate.
- – A more extreme, unconventional approach would be a diet such as the Swank diet, as described above.
A Final Precaution
Conventional medications for the treatment of MS are proven therapies, whereas diets and supplements are not. These dietary approaches should not be used instead of conventional medications. It is likely that using diets and supplements in addition to proven therapies would be beneficial, but this has not yet been supported by sufficient evidence. Also, although unlikely, there is a possibility that dietary approaches could decreased the effectiveness of conventional MS medications.
References and Additional Reading
Bowling AC. Complementary and Alternative Medicine and Multiple Sclerosis. New York: Demos Medical Publishing, 2007, pp. 87-105.
Bowling AC, Stewart TS. Dietary Supplements and Multiple Sclerosis: A Health Professional’s Guide. New York: Demos Medical Publishing, 2004.
Fragakis AS. The Health Professional’s Guide to Popular Dietary Supplements. The American Dietetic Association, 2003.
Jellin JM, Batz F, Hitchens K. Natural Medicines Comprehensive Database. Stockton, CA: Therapeutic Research Faculty, 2005.
Polman CH, Thompson AJ, Murray TJ, Bowling AC, Noseworthy JH. Multiple Sclerosis: The Guide to Treatment and Management. New York: Demos Medical Publishing, 2006.
Swank RL, Dugan BB. The Multiple Sclerosis Diet Book. New York: Doubleday, 1987.
Ulbricht CE, Basch EM, eds. Natural Standard Herb and Supplement Reference: Evidence-Based Clinical Reviews. St. Louis: Elsevier-Mosby, 2005.
Anon. Omega-3 oil: fish or pills? Consumer Reports 2003;July:30–32. Bates D, Cartlidge NEF, French JM, et al. A double-blind controlled trial of long chain n-3 polyunsaturated fatty acids in the treatment of multiple sclerosis. J Neurol Neurosurg Psychiatry 1989;52:18–22.
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