Nutrition and Spinal Muscular Atrophy

Reviewed by: HU Medical Review Board | Last reviewed: August 2021

Proper nutrition is important for everyone, but especially for people with spinal muscular atrophy (SMA). Many people with SMA have low height and weight because of poor nutrient intake. Difficulty swallowing and other feeding problems often lead to malnutrition. On the other hand, low physical activity can lead to overnutrition, including obesity.

We do not yet know the specific nutrition requirements, best diets, or ideal feeding tube methods for people with SMA. This means doctors must make nutritional suggestions based on each person’s needs and factors. The goal is to maintain a diet that reduces illness while maximizing growth and quality of life.

Why is nutrition important for people with SMA?

We need nutrients from food to give us the energy to breathe, move, and grow. Poor nutrition can worsen muscle weakness and limit growth for people with SMA. Nutrition experts have seen that a balanced diet provides many benefits to people with SMA, including:1

  • Improved growth and motor function
  • Better breathing
  • Lower risk of illness
  • Better quality of life

However, maintaining a balanced diet is not easy for people with SMA. Muscle weakness causes a range of problems that affect feeding and nutrient intake. For example, people with SMA often experience:2

  • Difficulty chewing and swallowing
  • Inhaling food or liquid into the lungs (aspiration)
  • Gastrointestinal (GI) problems like constipation or diarrhea
  • Gastroesophageal reflux disease (GERD), also known as acid reflux
  • Low or high blood sugar
  • Undernutrition or overnutrition

Every person with SMA has a different experience with nutrition and feeding. Everyone has different nutritional needs. There are not yet any studies that show a certain diet is best for people with SMA.3

How is nutrition monitored in SMA?

Soon after diagnosis, families should meet with a registered dietitian or nutritionist. These are experts in designing nutritional therapies, especially if nutrient intake is affected by the disease. Infants and children with SMA should see a dietitian every 3 to 6 months. Nutritionists will monitor growth by measuring weight and height. Other tests they may perform include:1,2

  • Bloodwork for vitamin D and calcium levels
  • Swallow study to assess ability to swallow different textures
  • Upper GI X-ray to assess reflux

Contact your doctor if you notice any sudden changes in weight or appearance.

What nutritional therapies can improve feeding?

Nutritionists will recommend a diet with food intake based on personal factors. Usually, infants and children are less active and have a lower muscle mass. This means they use less energy and need fewer calories.

Depending on the type of SMA, people may be at risk of either undernutrition or overnutrition. For example, children with type 1 or 2 SMA often experience undernutrition because of feeding problems. Children with type 2 or 3 SMA can suffer from overnutrition because of inactivity. This may lead to obesity. The goal for everyone is to balance calories, fat, proteins, carbohydrates, vitamins, and mineral supplements.4

Nutritionists will recommend diet changes for each person’s specific needs. This could be increasing or decreasing calories. Or, it could be avoiding foods that are hard to chew and those that increase the risk of aspiration and reflux. Some examples of diet changes include:1

  • Eating smaller meals to prevent reflux
  • Choosing softer foods that are easier to chew and swallow
  • Avoiding thin liquids that are easy to aspirate
  • Following a low-fat diet to prevent GERD

Doctors can also suggest devices and seating positions that improve feeding. In the case of serious acid reflux, nutritionists can determine if medicines or surgeries are needed.1,4

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What are feeding tubes?

A feeding tube provides nutrition directly through a tube to the stomach. Feeding tubes can be used to supplement oral feeding or as the only method of feeding.1

Children with type 1 or 2 SMA often need a feeding tube. Whether a feeding tube is necessary depends on each person’s specific needs. Your doctor may recommend a feeding tube if your child:1,4

  • Cannot swallow safely
  • Cannot meet nutrient needs by mouth
  • Is not growing well or maintaining weight
  • Cannot drink enough fluids
  • Is sick and not able to eat or drink for a period of time
  • Is undergoing surgery

There are several types of feeding tubes. Your doctor will help decide what type to use depending on how long it is needed and other specific factors. Feeding tube options include:1

  • Nasogastric (NG) tube – a small tube inserted through the nose meant for temporary use
  • Gastrostomy (G) tube – a small tube surgically placed through the skin meant for longer-term use
  • Gastrostomy-Jejunostomy (G-J) tube – a small tube surgically placed with 1 port for the stomach and 1 port for the small intestine

After placing a feeding tube, your dietitian will help make a plan for feedings and prescribe formulas and supplies. There are several types of feeding formulas based on the type of protein used. Your doctor will suggest a type of food formula, depending on food allergies, feeding tubes, and other factors.1

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