(11) Multiple sclerosis
Multiple sclerosis is a common disease of unknown cause
in which multiple plaques of demyelination occur within the brain and
spinal cord. MS affects about 80,000 adults in the UK, and the most common
age of onset is between 20 and 45 years. It is more common in women than
men. MS occurs worldwide but the prevalence varies widely, being proportional
to the distance from the equator: prevalence progressively increases as
distance from the equator increases.
There is no cure for MS, so patients are often motivated to try anything
that might help, including dietary manipulation, although nutritional
interventions are not always evidence-based. The case for dietary change
in MS is not proven, but there is some evidence that the disease is linked
to the consumption of large quantities of saturated (animal) fats. Prevalence
of MS seems to be lower where polyunsaturated fats are eaten in preference
to saturated.
- Positive dietary advice can help patients to feel in control of the
disease and may deter them from trying potentially harmful interventions.
- Being overweight is not helpful in a disease characterised by muscle
weakness, and it can also cause difficulties for carers if the patient
needs to be lifted.
- The symptoms of MS (eg, fatigue, depression, progressive disability,
swallowing disorders) can affect food intake and the ability to shop
for and prepare food. Patients may require the support of family, friends
and neighbours. Sip-feed nutritional supplements may help to improve
nutritional intake if the sufferer cannot eat.
- There is some evidence that reduction of fat intake may be beneficial
in MS, and a diet of reduced fat content is advocated, as for the population
in general.
- Patients should be advised to follow healthy eating guidelines, eg,
plenty of fruit and vegetables, and bread and cereals, preferably wholegrain.
- Foods containing animal fats (eg, fatty meats, full-fat dairy produce,
pies, pastries, cakes and biscuits) should be avoided as much as possible.
- It is important to have a balance between the two types of polyunsaturated
fatty acids (omega-6 and omega-3 polyunsaturates). Polyunsaturated margarines,
fats and oils (eg, sunflower or soya spread, and sunflower, corn, safflower
and soya oils) are a good source of omega-6 polyunsaturates.
- Oily fish (eg, mackerel, herrings, kippers, sardines, whitebait, trout,
salmon) is a good source of omega-3 polyunsaturates. Fish oil supplements
containing omega-3 fatty acids can be recommended for people who do
not like oily fish.
- As the diet may contain high levels of polyunsaturates, a good intake
of vitamin E, vitamin B6, zinc and vitamin C is needed. Vitamin
E is the main antioxidant that helps prevent peroxidation of polyunsaturates
and vitamin C helps to protect vitamin E. Zinc and vitamin B6
are part of the enzyme delta-6-desaturase which is involved in conversion
of linoleic acid (found in polyunsaturated fat and oils) to its longer
chain derivatives.
- There is some evidence for an increased requirement of vitamin B12
in MS. This can be achieved by consumption of foods such as lean red
meat and liver. Some patients have regular vitamin B12 injections.
- Some patients with MS take evening primrose oil. The rationale for
this is the high content of gamma-linolenic acid which is a substrate
for prostaglandin production. Some individuals appear to benefit but
clinical trials have shown little evidence for this.
- Other types of diet, including gluten-free diets and allergy (exclusion)
diets, have been tried for MS, although supportive clinical evidence
is lacking.
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