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Fats and fatty acids

Fats are made up of fatty acids, and are an essential part of our diet. We need fats for energy, cell function and to ensure that we get some essential fat-soluble nutrients.

Fats in our diet come in two main forms. Saturated fats are hard at room temperature, such as butter, cheese and the fat on meat. Unsaturated fats are soft or liquid at room temperature. You would find them in fish oils and oils from plants and seeds. In a fat molecule there are spaces for hydrogen atoms to attach. A saturated fat molecule has no spaces left – it is saturated with hydrogen. Unsaturated fats have spaces where hydrogen could attach.

A generally healthy diet makes sense for those with MS. Maintaining a healthy weight can reduce the impact of some MS symptoms, including insomnia and incontinence. Adjusting your diet can be a relatively easy way for you to take control of your MS and try different options. However, a healthy diet needs to take into account cost, convenience and palatability too. You will find more on choosing an appropriate diet for MS in our series on diet and MS.

In this section, we look at the different kinds of fats and the evidence for their effect on MS. The evidence comes from studies using different amounts and types of fatty acids, and providing them in different ways, along varied dietary regimes. This means that evaluating them can be difficult. Although there are some interesting findings, there is not enough evidence to suggest that all people with MS should follow any specific dietary regime. 

Saturated Fat

In the UK, we are all advised to reduce the amount of saturated fats in our diet and replace them with unsaturated fats. Saturated fats include coconut and palm oil, as well as fats from dairy and meats. High levels of saturated fats are associated with risk of MS, and also obesity and cardiovascular issues. Obesity is linked to higher levels of inflammation and immune stimulation, and may make MS symptoms worse.

For children with RRMS, a high fat diet, especially if high in saturated fats, has been shown to increase relapse rates. Replacing the fat in this diet with vegetable fats reduced the relapse rate.

In another study, adults with RRMS ate a plant based diet low in saturated fats for a year and reported weight loss and improvements in fatigue, mood and quality of life, compared with those on a regular American diet. The benefits may have come just from the weight loss and a sense of control, and no difference in lesions or disability score was noted.

Monounsaturated fat

If there is just one space in the fat molecule for hydrogen to attach, the fat is known as a monounsaturated fat (MUFA). Olive oil and avocados are the best known sources of MUFA. Olive oil is a major component of the Mediterranean Diet which is often suggested as a beneficial alternative to a typical Western Diet. For people with MS, the Mediterranean Diet may slow the progress of the disease and protect brain function.

A diet high in MUFA (olive oil) tends to lower cholesterol levels in the blood. High cholesterol is associated with heart disease, and also with inflammation and stronger immune activity which could make MS symptoms worse. This benefit might come from Oleic Acid, the main fatty acid in olive oil, or alternatively from other compounds in the oil. Phenols from olive oil have been shown to protect animal brains against oxidative stress, protect nerve cells and stabilise the blood-brain barrier, but full trials in humans are still necessary.

Polyunsaturated Fat

Where there are multiple spaces on the molecule for a hydrogen atom to attach, this is a polyunsaturated fat. Our bodies cannot make polyunsaturated fatty acids (PUFA), so we need to include them in our diet. PUFA are also known as essential fatty acids, and are vital components of our brain tissue and myelin.

There are two main types of PUFA, known as omega-3 and omega-6 PUFA. In each case, our bodies convert the forms we eat into substances that we need. The end products include prostaglandins and other substances which have complex effects on the immune system. Experimental studies are difficult to compare, as they use fatty acids from different positions in the metabolic pathway, at different doses and mixed with other nutrients.

Omega-6 PUFA pathway in the body

The omega-6 pathway PUFAs are found in plant oils. Sunflower and corn oils, nut oils, and pumpkin seeds contain linoleic acid (LA). Gamma-Linoleic Acid (GLA) is the next stage in the pathway, leading some to assume that it would be more effective in the body than LA. GLA is rarer in foods than LA, but is found in evening primrose oil and borage. There is no real shortage of omega-6 PUFA in a Western diet, as vegetable cooking oils, salad dressings and margerines contain good levels of LA.

In the 1970s, studies of Linoleic Acid on MS showed promising results. They seemed to show that LA slowed progression of the disease, but only if it was taken early. Later reviews disputed this, and described the effect as suggestive but not definite. Experimental studes also showed that GLA in the form of evening primrose oil might suppress T cell activity, and lower the immune response. Conflicting reports suggest that omega-6 PUFA might promote inflammation, which would make them less helpful to those with MS. It's fair to say that there is no conclusion just yet for people with MS.

Omega-3 PUFA pathway in the body

Alpha-linolenic acid is found in flaxseed, hemp and leafy vegetables in small quantities. EPA and DHA are found in fish oil, and are commonly found in supplements. Again, experimental studies vary in dose and type of supplement, but there is evidence that omega-3 PUFA can boost remyelination, suppress immune response and protect nerve cells. People taking omega-3 supplements or eating plenty of oily fish reported general improvements in relapse rate and progression of MS, although not all studies have supported this. Omega-3 PUFA are associated with other health benefits, particularly heart health.

​Mixed PUFA

Canola and rapeseed oils, walnuts, flax, hemp and chia seeds have both omega-6 LA and omega-3 ALA as well as some Oleic Acid too (MUFA). For vegans and vegetarians, these are particularly useful sources of omega-3 PUFA.

One small recent study showed lower relapse rates and slower progression of MS in those taking a mixed PUFA supplement alongside a healthy diet, compared with those taking olive oil (MUFA) instead. These studies are small and have higher than average relapse rates in their control groups, which could mean that their findings are unreliable. Mixed PUFA supplements have also shown benefit in protecting optic nerve cells in mice with a similar disease to MS, with the expectation that mixed PUFAs could protect against optic neuritis in people.

There are some side effects from adding PUFA supplements to the diet. Some people find the supplements taste unpleasant or that large amounts of PUFA give them diarrhoea. If you do decide to take PUFA supplements, then you should be aware that there is potential to develop Vitamin E deficiency. Often, PUFA supplements include Vitamin E to counteract this. Large Vitamin E doses are not required, just the normal daily recommendation is enough.

The kind of fats you eat affect the microbes in your gut, and there is evidence that plant based fats support a more diverse community of gut microbes. Many of these produce beneficial substances that are necessary in order to get nutrients out of the food we eat, and also reduce inflammation in the gut. Some of the health benefits noted with plant based PUFA could come from this effect, which has only recently become widely studied.

Last updated: March 2018
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