Some thoughts on … Nutrition for people with Spinal Muscular Atrophy (SMA)

SMA Food

In general, intentionally putting on weight when you have SMA is only a good idea if the weight is useful muscle (although there is an important exception to this idea below). Increasing the amount of fat on a person’s body is adding ‘dead-weight’, the body will only use it as nutrition in lean times and, when the muscle power available is limited, it is more likely to lead to exhaustion than to contribute to a person’s well-being. Once a certain level of body fat is exceeded it is counter-productive to maintaining muscles in normal daily living and so the muscles tend to deteriorate since useful exercise is now beyond their abilities.

There are times when it is necessary to build up body fat, typically when you are expecting not to be able to eat so easily or to lose your appetite, and especially when your need for energy increases at the same time. These might be in the early autumn (fall) and spring seasons when there is a risk of colds followed by chest infections and also, especially important, before surgery.

The diet needed to maintain peak performance for someone with SMA is, therefore, one which an athlete would use to build up muscle for a competition … pretty much the daily challenge faced by those with SMA. Think protein for muscle building and only the amount of carbohydrate needed to maintain input calories, likely to be around 1,000 kCal. More than this is likely to put on fatty tissue, or simply not to be adsorbed.

Also note that around 25% of the body’s resting energy supply is expected to be used by the brain1, however in the case of individuals with SMA this proportion is probably higher as the muscular proportion is likely to be reduced. Add to this that heightened intelligence2 is normally associated with SMA leading to, perhaps, choosing foods which provide energy for brain development and function (Vitamins B12 and D3, Omega 3, Creatine3).

The amount of protein one should aim for in the diet is around one gram of pure protein per kilo of body weight (tuna is 26% protein; lean steak: 36%; chicken breast: 30%; egg: 13%; milk: 6%). This is a large amount of protein by ordinary nutrition standards, and may be difficult to eat if not carefully thought out so check out protein to calorie ratios for various foods. A solution which is fairly easy to accomplish is to liquidise food to make it easy to swallow, but other stratagems can be used too, like whipping a raw egg into freshly mashed potatoes.

When liquidising food, remember that it is probably being prepared for someone with a fairly sophisticated palate. You are making the food easy to eat, not preparing food for a baby, so herbs and spices and strong tastes in general may well be preferred and a range of textures will also make it more interesting, but be prepared to change the amounts of flavourings used in a dish when you develop recipes to be eaten in liquidised form as they will taste slightly different from their un-liquidised versions.

One of the problems faced by those eating a high protein diet can be constipation, particularly if red meat (see below) is a main source of the protein. However increased muscle tone can improve bowel function for those with SMA. If a balance can not be achieved be prepared to use a gentle laxative as necessary. Ex-Lax (“magic chocolate”) is a stimulant laxative for very occasional use, which is often highly acceptable to children; however make sure the amount matches body weight since you can lose nutritional value by clearing bowels too soon (you’ll probably be using a quarter of a segment at a time). Overuse of stimulant laxatives can reduce bowel strength so, if it impossible to regulate bowel movements with diet, consider a regular stool softener like Movicol.

It is possible to increase the protein content in your diet by adding protein powder available from the suppliers used by athletes and fitness enthusiasts, but do take great care in working out the correct amounts. Again, beware constipation.

Finally, as any owner of young animals knows, changing foods is difficult. Don’t try to jump straight into a high protein diet from a starchy one, the body simply won’t be ready to assimilate it.

Accessing the Energy

Once the diet is becoming more useful to feed muscles you need to consider how it is going to get to those muscles in a usable form. The transport of energy in an SMA affected body is slightly messed up, if only from poor circulation in the extremities and the lack of the distribution mechanism inherent in moving limbs, etc. When food gets to the muscles there are things which can be used as dietary supplements to make take-up more efficient.

L-Carnitine4 carries energy to muscles in an easily used form. It has a fairly short life so it can’t carry energy to store and use at a later date, but only in the short term. It is available from red meat and animal tissue in general and as a dietary supplement; there are even vegetarian forms available.

Creatine binds the energy available to muscle tissue in such a way as to preserve it (like a store cupboard); the bond breaks easily when needed releasing the energy for the muscle to use. The body makes its own Creatine but it can be supplemented in a powdered form often taken with glucose. There may be no benefit from supplementing it if the body is naturally at capacity, as can happen with some people, but excess Creatine is excreted so there is little risk from taking too much. If you take Creatine, warn your doctor if you have a urine test as it will show up and cause concern.

Athletes use Creatine to build muscle power, typically in doses about three times what their body is naturally producing. Rumours of Creatine causing kidney damage seem to be unfounded5: “In 2004 the European Food Safety Authority (EFSA) published a record which stated that oral long-term intake of 3g pure Creatine per day is risk-free. The reports of damage to the kidneys by Creatine supplementation have been scientifically refuted.”

Salbutamol makes take-up of energy within the muscle more effective. There is now a substantial number of people with SMA who have a successful track record of beneficial effects from the systemic use of Salbutamol. A side effect of this is to build up muscle tissue rather than fat deposits.


The problem with a high protein diet is that many of the foods are quite hard work to chew, and after chewing to swallow. The use of a liquidiser/blender is an obvious starting point but care should be taken not to turn all food into an amorphous mush.

Some people with SMA also report that nobody has taught them how to swallow successfully. Frequently, taking food by mouth is a very real problem, but surgically by-passing the need is not necessarily the best solution if instruction, diet and exercise can be used to avoid intervention. Any surgical implant increases the risk of infection on a daily basis in a person who is already dependent on complex care.

The instruction needed is:

  1. Chew food in a reasonable quantity, too little is as bad as too much.
  2. Push food to the front of your mouth and hold it there with your tongue.
  3. Breathe in while the food is safely away from your air-way and hold your breath.
  4. Now swallow. If you need to breathe, or if the epiglottis happens to relax as the food passes, the air will be going in the opposite direction to the food and the risk of choking is very much less!
  5. When the food has gone down, breathe out hard.
  6. If not everything has gone down properly first time repeat until all the food has gone from your mouth.

The use of nutritional drinks like Fortisip has a very proper place (Fortisip Extra has 20g of protein in 200ml) as they are, after all, a balanced diet in a bottle, and are easy to drink. Experiment with the available flavours, some are much nicer than others but not everyone agrees on which ones! Don’t forget to use the swallowing principle above while drinking as well as when eating.

Energy snacks are also very useful. It’s worth categorising them into fast energy (Bounty bar which is made of coconut, glucose and chocolate) and slow release energy (banana!) and choosing which one is best at what time. Also don’t forget Vitamin C which can be missed in ‘easy’ food.

3/ ref 42: Rae C, Digney AL, McEwan SR, Bates TC (October 2003)
5/ ref 20:


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