MS research in nutritional science

Why is nutrition important?

What role does nutrition really play in causing or treating MS? This page looks at the current scientific evidence for links between MS and what you eat.

A healthy diet for everyone

Diet is a major influence on our health. World Health Organisation guidelines (1990) recommend that everyone should increase their daily intake of fruit and vegetables, complex carbohydrates and high-fibre foods, and reduce their fat consumption. This advice is intended to lower the risk of certain cancers and disease.

Diet and disease

The role of nutrition in disease can be complex. Nutrients interact not only with disease but with each other.

Certain fats, antioxidants and minerals are all important factors in stroke, heart disease and cancer. It is difficult to isolate and analyse the role of any one nutrient in disease.

Reseach shows that poor diet, illness and ageing all have an impact on the body's nutrient levels. These in turn affect the vital role of the immune and other physiological systems in resisting disease and infection.

Diet and MS

There is no clear evidence that diet alone can affect MS. But it does make sense to support your immune and central nervous systems by following a healthy diet.

The role of lipids in MS

Lipids are important for energy and for the functioning of the immune and nervous systems. They may play a significant role in MS.

What are lipids?

Fats and oils (lipids) are made up of fatty acids, which are simple chain-like structures. Fats and oils are used by the body:

• as sources and stores of energy.
• to maintain healthy cell membranes.
• for conversion into hormones and hormone-like substances (called eicosanoids) which act on the immune, vascular and central nervous systems.

Essential fatty acids (EFAs)

Polyunsaturated fats (PUFAs) are made from linoleic and alpha-linolenic acid, which are essential polyunsaturated fatty acids (EFAs). EFAs cannot be made by the body, and must be obtained from the diet. Our bodies make them into long chain PUDAs, e.g. arachidonic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

The two main groups of EFAs and PUFAs are:

• N-6 (or omega-6) - the linoleic family: found in seeds, legumes, sunflower, safflower and corn oils.
• N-3 (or omega-3) - the alpha-linolenic family: alpha-linolenic acid - found in dark black vegetables; EPA and DHA - found in oily fish and other seafoods.

Evidence for the role of lipids in MS

The role of lipids in the immune and nervous systems in MS is not yet clear. There have been relatively few detailed studies so far.

Research theories

Research has concentrated on the following areas:

• 60 per cent of the brain is made up of lipids. Could the CNS of people with MS be sensitive to lipid intake in early life, making them vulnerable to myelin breakdown, infection or autoimmune attack?
• would a dietary supply of lipids, necessary for repair and maintenance of the brain, encourage repair processes in MS?
• could supplementation with specific lipids reduce damage to the myelin sheath in the CNS caused by autoimmunity (an inappropriate response of the immune system)?

Epidemiology

Epidemiology is the study of disease in populations. MS is a complex disease: genetics, diet, viruses and other influences may all be involved.

Several studies have found a link between MS and lipids. MS is more common in countries where diets are rich in saturated fats, while it occurs less where diets are rich in PUFAs. The link may not be straightforward. We don't know if lipids have a direct role in causing MS or if they indicate another significant aspect of lifestyle.

Experimental studies

Studies in laboratory animals and in humans have shown that n-3 and n-6 PUFAs can strongly influence the immune system. There is convincing evidence that the n-3 fatty acid DHA is used for brain growth, development and vision.

In experiments which mimic MS in laboratory animals, n-6 fatty acids have been shown to prevent or reduce disease.

Biochemical studies

Some studies have shown reduced levels of EFAs and other PUFAs in the blood of people with MS, but it is not clear whether there is a direct association with MS. The changes may indicate disturbances in fatty acid metabolism. Whatever the reasons, low levels of EFAs can be corrected by an increased dietary intake.

PUFA trials

There is evidence that supplements of n-3 or n-6 fatty acids are beneficial in autoimmune inflammatory conditions (such as rheumatoid arthritis and lupus).

Trials by Bates (1978) and Millar (1973), of the effect of sunflower oil (rich in linoleic acid) in MS, showed a reduction in relapse rate and severity. However, Paty's study (1978) showed no effect. These trials were re-evaluated by Dworkin (1984), and showed reduction in relapse rate and severity. A slowing of long term progression was noted in mild relapsing/remitting MS. In the trials, people took three to four tablespoons of sunflower oil daily. The long term effects of this supplementation are unknown.

A trial with fish oil by Bates (1989), found no significant effect, although there was a small trend for less deterioration.

Two other studies have reported beneficial effects. Fitzgerald (1987) studied a diet low in saturated fat and rich in n-6 and n-3 PUFAs. Swank & Dugan (1990) followed people on a diet very low in total fat (but with n-6 and n-3 PUFAs) over 30 years. No deterioration was noted, but because the study was uncontrolled some scientists argue that we cannot rely on the results.

The role of vitamins

Antioxidant and B group vitamins are important for general health. But what do we know about their significance in MS?

Antioxidant vitamins

Antioxidant vitamins protect your body against damage by oxidation, a factor in ageing and disease.

Found in fruit and in dark black and yellow-orange vegetables:

• vitamin A promotes good vision, protects against infection and maintains healthy skin and mucosal surfaces.
• vitamin E maintains healthy cell membranes.
• vitamin C is important in infection and stress.

Antioxidants and MS

Oxidative processes might be an important factor in MS. Few studies have been done, but lower than usual blood levels of vitamins A and E have been found in some people with MS. Normal blood levels of vitamins were restored by increasing vitamin intake through food or supplements.

The low levels found in some people did not amount to clinical deficiency. However, it is thought that antioxidants could be significant for some people, because there are similarities between the clinical signs of vitamin A and E deficiency and of MS.

Vitamin E

Evidence suggests that to protect against oxidation, you need more vitamin E if you increase your intake of EFAs and PUFAs. However, most oils which are rich in PUFAs also contain vitamin E.

Although we cannot be sure of the precise role of antioxidant vitamins in MS, you should include them in your diet.

B vitamins

B vitamins help enzymes in the body to make proteins and produce energy.

Vitamin B12

Vitamin B12 and folate play significant roles in cell renewal, blood cell formation and DNA replication. Deficiency in either B12 or folate can cause neurological complications similar to some clinical signs of MS.

In the few studies done for MS, some people have been found to have low levels of B12. However, the relationship is not clear; there is no evidence that B12 deficiency is a cause of MS.

B12 deficiency can be corrected through diet or injections.

Folate

Some people with MS have low levels of folate. It is not known yet whether this is because of reduced calorie intake, the disease process, or both. People with restricted mobility may taken in less than the recommended daily amounts of B vitamins, including folate. Low levels can be corrected by an increased intake of folic acid in the diet/

Not everyone with MS shows a lack of B12 or folate, but any suspected deficiency should be properly investigaed. You should always seek medical advice if you are considering taking supplements. Taking folate as folic acid when you have a B12 deficiency can be dangerous.

Minerals and trace elements in MS

Some minerals and trace elements help to protect cells against oxidation and are also involved in demyelinating disease in animals.

Zinc and copper

One study showed some younger people with MS to have low blood levels of zinc and copper, although other reports do not confirm this. At present there is no agreement amongst researchers as to their significance.

Daily zinc supplementation of 300 micrograms has been shown to be potentially harmful to the immune systems of young healthy people.

Selenium

Studies of selenium and MS have produced inconsistent data, and researchers have concluded that levels in individuals reflect concentrations of thsi element in the local environment. A Danish study showed low activity of glutatione peroxidase, an enzyme containing selenium, in people with MS, but other studies have nto confirmed this.

Other minerals

There is no scientific evidence to suuport the use of mineral supplements such as iron or magnexsium, or trace elements such as chromium, germanium or vanadium, by people with MS.

Dietary supplements

While there may be reasons for using a supplement in some cases (e.g. if you do not have access to adequate fresh food sources) most people can and should obtain the nutrients they need from food.

Paying attention to special diets

MS may not be the only reason for needing to pay special attention to your diet.

Pregnancy

If you are pregnant, or planning for pregnancy, get advice from health professionals on your diet. All pregnant women should avoid fish oils, liver and liver products as they are rich in vitamin A which may harm the foetus. The Department of Health recommends a dietary supplement (400 micrograms) of folic acid to lower the risk of spina bifida in babies. Some women with MS may have lower folate levels than normal.

Food allergies

Theories on a relationship between MS and food allergies have been widely publicised. There is no conclusive scientific evidence that food allergy is a factor in MS. It is just as possible for people with MS to have an allergy as it is for the general population.

Begetarian and vegan diets

If you are vegetarian or vegan with MS, you will need to pay attention to your B12 and folate levels. You may run the risk of reduced calorie intake or low levels of vitamins B12 and D, calcium, iron and zinc. You can avoid these problems by planning your diet carefully. Your GP or a dietitian can give expert advice.

Bladder and bowel funtion

Everyone should drink at least one or two litres of liquid each day to keep healthy. Continence advisors can explain how diet can help bladder or bowel problems.

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