Height is determined by length of the long bones and skeleton. Arms and legs have special areas across them (below the knees and wrists) called “growth plates” made from flexible cartilage. The cartilage is turned into hard bone in these areas by bone cells, called bone matrix. Matrix itself is made of a material called “hydroxyapatite” and it is like a chalky ceramic. Matrix is added a layer at a time onto the end of the plates, gradually making the bone longer.
Babies’ skeletons don’t start to develop fully until they start walking, but some parts of soft bones start to harden during the first year. For example, on their skull in areas called fontanelles, and around the neck and shoulder bones, when they start to hold their head up properly. Bone growth is stimulated by mechanical movement, which is why height can be encouraged through physical activity. This has been seen during the covid pandemic, where lack of regular exercise in children resulted in a slight drop in average height.
Height is also a general growth process that is related to energy production, tissue building and balanced nutrition. This is seen in undernutrition, where lacking many types of nutrition due to lack of supply or illness can slow down height gain, depending on how long the period lasted for.
Specific micronutrients involved in gaining height
Calcium and phosphorus
Calcium and phosphorus are the main micronutrients used in making bone matrix, which is the foundation for bone growth. Both nutrients are absorbed through the gut as dissolved form (sometimes we call these electrolyte form, as found is in milk and electrolyte drinks). From there, it enters the bone cells, where it is converted into the solid bone matrix is where most of the body’s calcium is stored. Calcium can go in and out of bone all the time, but in growing kids it is mostly “in”.
Lack of calcium and phosphorus in the diet in infants and children has been shown to cause defects in the bone cells, which prevents new matrix forming and weakens the skeleton structure . Calcium absorption is directly related to height scores in children .
Vitamin D has different roles in how the child’s body controls calcium movement around the body. First, it helps the intestine to absorb calcium into the body from the food nutrients in the gut. Secondly, it helps control calcium balance once it is in the body. Thirdly, vitamin D has some growth promoting effects. In children, movement of calcium around the body is more active than in adults.
Lack vitamin D in the child’s diet causes a lack of calcium and is the main cause of a condition called “Rickets”  This is when bones don’t make enough solid mineral, so they stay in the soft form and grow into a bent shape, as kids put on weight. This causes problems in achieving height and difficulty walking, because bones do not grow in a straight line. Children with shorter than average height for their age have been found to have lower levels of vitamin D in their bodies .
Vitamin K has a special role in moving calcium into bones. It helps to transport calcium around the body after it has been absorbed, and then works on a specific process that controls how bone cells take up calcium and deposit it into bone matrix. This also works in reverse, to control release of calcium from bone. Infants rely on vitamin K from mother’s supplies before birth, but as they grow, they obtain some of it from breastmilk. As children get older, their levels of vitamin K have been shown to height and bone matrix formation .
Vitamin C, Zinc
Vitamin C & Zinc are only part of the bone that children make as they grow taller is made of matrix. In fact, it is only about 25% of bone. The rest is made from a material called collagen. Collagen is very elastic, but when combined with matrix, it becomes tough and slightly flexible, and this is what allows bones to stay strong and not break, as children gain weight. Both vitamin C and zinc are used to make new collagen from protein in the diet.
Zinc has other important roles the relate to height growth. One is to control the production of new bone cells, and the other is to form part of bone matrix. Bone matrix is mostly calcium and phosphorus, but also contains tiny amounts of other minerals including zinc. Zinc deficiency is regarded as one of the most important micronutrients that cause stunting in children and including zinc in the diet from 3 months to 5 years improves height gain .
Magnesium, Copper & Manganese
Like zinc, magnesium, manganese and iron are required in tiny amounts in bone matrix, while copper helps with collagen strength. These minerals also help to control energy production in bone and muscle cells to keep them regenerating. Low magnesium slows down the absorption of calcium into the bone matrix after it has been absorbed into the body. The intake of magnesium in a study of 4-8 year-old children has been shown be associated with bone matrix formation all over the body . In one Chinese study of children from 6months to 3 years of age, those with lower height gain also had lower levels of zinc, magnesium, iron and copper in their bodies .
B-vitamins are important for production of energy in growing tissues of the body, including bone, muscle, blood cells and their controlling processes. In a study of Indian children of 6-36 months of age with lower height for age, the addition vitamin B12 and folic acid (vitamin B9) to the diet significantly improved their height gain .
This mineral controls the activity of a special organ in the neck called the thyroid gland. This gland controls the overall levels of energy in the body in children with increased growth demands, meaning that it like a master controller of height, but also controls brain growth. Iodine deficiency can occur during pregnancy, but also affects growing children. In a study of African children up to 5 years of age with iodine deficiency, almost 30% were under-height, and 10% were underweight .
This vitamin acts like a growth promoting factor in tissues, not only during pregnancy but throughout childhood. Vitamin A deficiency has been a major problem in south Asian countries in recent years, and although is normally associated with vision problems, children with those problems also show growth problems. A study of vitamin A introduction to children under 5 years who were stunted, had dry eyes and were lower in body weight, later showed moderate improvements in height growth after 4 months .
What does the eye use micronutrients for?
The main function of the eye is vision. Although this process happens automatically from birth, and gradually increases in its ability to recognize more complex information, performing this task requires lots of complicated systems working together. The main working parts of the eye are the lens, which focuses images, and the retina, a multi-layered structure that puts together those images and sends them via a nerve to the brain.
The main nutrient consuming parts of the eye are the more active parts that include:
- The retina (light detection)
- The muscles controlling the lens (focusing and sharpening light images)
- The eye lid muscles (protecting the outer eye parts)
- Glands that supply eye fluids (protecting and lubricating the eye)
These are supported by a special network of blood vessels that deliver oxygen and nutrients to keep these systems working effectively. We can also include the optical part of the brain, to which the retina is directly “wired in”, and is one of the most active parts of the brain – only 2% of the body, but using about 20% of its energy! .
How to supply these nutrients properly
It is very difficult know (a) if children have a nutrient deficiency, (b) which one it is and (c) if it is related to a problem with height growth. Because many different nutrients are involved in height gain, it is useful to provide a comprehensive source of micronutrients, at levels that are adequate for specific age groups.
This can be done through:
- Using nutrient dense formulas and supplementary sources of nutrients
- Providing a balanced diet of fruit, vegetables and wholegrains
- Providing an absorbable source of protein, such as from eggs, meat, fish or dairy products
- Providing enough water
- Providing food that has been fortified with micronutrients and a source of reliable protein in vegetarian or vegan diets
- Avoiding junk food (high fat, high sucrose, lower nutrient density)
- Avoiding highly processed carbohydrate rich foods
- Avoiding sugary drinks
- Using iodized salt instead of normal salt in cooking
What exercises or activities can help kids with their height growth?
- Ball sports
- Walking and running
- Swimming (can be done less often)
- Hanging on monkey bars
- Getting plenty of sleep
- Eating dinner early
Note: a variety of different exercises is good, and avoid heavy weight lifting
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