Feeding and SMA

Proper nutrition is essential for the development of the child in general. In the presence of neuromuscular disease like SMA obesity and heart complications can accelerate the evolution of the disease.
Every molecule of food plays a different role in the body. The main nutrients are:
- Carbohydrates;
- Proteins;
- Vitamins;
- Minerals.
It defines food any substance that is able to exercise one or more of the following functions:
- provide energetic material for production of heat, work or other forms of energy (proteins, glucids, lipids);
- provide plastic material for the growth and tissue repair (proteins and minerals);
- provide catalytic material for metabolic reactions (minerals and vitamins).

Studies on vitamin B12 and folic acid in SMA suggest that these vitamins act on the specific sites of the motor neurons to improve their functionality and thus slow the progression of the disease. At present there is no evidence that individuals affected by SMA have a level lower than normal of vitamin B12 and folate, but a supplement of these vitamins in the diet is often recommended because they are water-soluble substances and the excess is eliminated in the urine, so there are no contraindications when taken in excessive doses.

Nutritional requirements of calories and proteins for healthy children:

0 - 6 months, 108 calories/kg and 2.2 g proteins/kg
6 - 12 months, 98 calories/kg and 1.6 g proteins/kg
1 - 3 years, 102 calories/kg and 1.2 g proteins/kg
4 - 6 years, 90 calories/kg and 1.1 g proteins/kg
7 - 10 years, 70 calories/kg and 1.0 g proteins/kg

Nutritional requirements of calories and proteins in healthy adolescents:
Males:
11 - 14 years, 55 calories/kg and 1.0 g proteins/kg
15 - 18 years, 45 calories/kg and 0.9 g proteins/kg
Females:
11 - 14 years, 47 calories/kg and 1.0 g proteins/kg
15 - 18 years, 40 calories/kg and 0.8 g proteins/kg

Nutritional requirements of calories and proteins in healthy adults:
25 - 35 calories/kg 0.8 g proteins/kg

As can be seen in healthy people the protein needs decreases with increasing age.

Nutritional requirements of calories and proteins in children with SMA:
60 - 80 calories/kg 2.0 g proteins/kg

From all this it can be concluded that:
- the amount of calories needed is lower than that of healthy children because a child affected by SMA moves and consumes just a few calories;
- the quantity of proteins should be increased to prevent protein catabolism of muscles: these are made of protein material and a child suffering from SMA can not afford to lose even a little of his muscle mass;
- the amount of vitamins and minerals should be similar to that of their peers: these substances are involved in enzymatic processes for the construction of tissues and children with SMA have no weaknesses in this regard.

A 10 years old child affected by SMA must weigh at least 10% less compared to a healthy baby because his muscles, already weak, can not support excessive weight. It needs to prevent obesity in order to allow the child to move to the best of his abilities. For example, an overweight in child suffering from SMA III will be the main cause for which he will stop walking.
The reduced muscle mass and the malfunctioning of the muscles (caused by minor innervation by the motor neurons) lead to reduced energy consumption.

Factors that influence the need for food:
- rate of growth of the child;
- type of constitution;
- degree of muscular activity.

Energy consumption and growth in patients suffering from neuromuscular diseases:
The children may seem underweight even if their weight is ideal. If the relationship between muscle mass and fat mass is right, they will not need to increase their weight as fat mass.
To find out if a child has a proper weight, in addition to the usual assessments (measurement of weight, height and cranial circumference), you can measure the amino acids in the blood, which are the building blocks that make up proteins.

Problems of food:
Why do children with SMA eat little? They often have problems chewing and swallowing and food becomes a long and tedious process.

As a result of respiratory infections a weakening can occur with a consequent malnutrition. How to act? Increase the density of foods: a liquid is more difficult to swallow than the solid food because it goes more easily into the trachea (dysphagia). In the most severe forms of SMA bulbar muscles are also involved and often the patients require the application of a PEG (percutaneous endoscopic gastrostomy) to allow the child to feed himself properly. In the medium forms of SMA swallowing problems are minor and are overcome by using thickening liquid. In the market there are also drinks jellied to "eat" water. These products are more dense than water and this makes it easier to swallow: when they arrive in the stomach they become water.

More food in small amounts of food: so that the child does not tire himself too much in chewing.

Introduction of food supplements in the diet: unfortunately there are few on the market and often the taste is not pleasant. There are also liquid supplements to the diet of children. It is important to follow the dosage recommendations on the packaging of supplements, even if they do not cover the entire daily requirement: this is because the protein must be taken with food to be metabolised by the body. The proteins incorporated with food are divided in the process of digestion into smaller molecules called amino acids; they are absorbed in the intestine, transported to the liver, from here to the tissues and organs, where they are again "assembled" to form structural proteins of the cells or enzymes and hormones. The protein excess is processed by the liver in waste substances such as urea, which is transported to the kidneys and then expelled in the urine. Hyperproteic diet can lead to fatigue kidney with associated damage, a balanced diet, helped by supplements, is better for child.

A child properly fed defend himself better against infections. In cases of medium-severe SMA a child weakened by respiratory infection tends to eat even less because of the phlegm, which makes it difficult to swallow. Insufficient feeding can cause hypoglycemia (low blood glucose), expressed at times with sudden vomits. If your child is ill and there is need to rapidly giving high glycemic index carbohydrates, it may be useful to him to drink water and sugar. In the United States was carried out a study in SMA and has been observed alteration of blood sugar in some children.

Dysphagia (difficulty swallowing) is worsening with respiratory infections. With problems in swallowing is more difficult to drink liquids that eating solids: the water can "go across" and create the resurgence. The phenomenon of “ab ingestis” (a phenomenon for which the food, solid or liquid, is sucked into the airways, causing pneumonia and other respiratory tract infections) occurs with a sudden pallor of the child while eating. With the pulse oximeter is easier to monitor the oxygen saturation in the blood: if suddenly the values fall drastically, the food definitely came into the trachea and doesn’t allow breathing. In this case it should immediately intervene with manual or mechanical operation to eject the food.

Often children with neuromuscular diseases suffer from constipation for a slow intestinal transit. An intestinal blockage is even more risky in SMA patients because the abdominal muscles are also involved: they are unable to effectively stimulate peristalsis, both in the starting section of the intestine and in defecation. Food is one of the factors to be amended to combat constipation: the diet must be rich in fibers but they are contained in substances with little pleasing flavors or that children do not like (fruit, vegetables, legumes and whole grains). There are products that contain fibers that can be added to foods as they are totally tasteless and do not alter the taste of food.

Dr. Marcello Villanova (neurologist)