Bone Development

1. Bone development is presented as the cumulative effect of a large number of interacting factors (genetic, hormonal, nutritional, environmental, behavioral) that activate bone cells first to build (the bone “modeling” of growth) and then to maintain (the bone “remodeling” of maturity) bone tissue. As a bone develops it must not only increase in length and width but also alter its shape and composition to accommodate the changing stresses and strains that are placed upon it in this dynamic stage. Bone modelling therefore involves the sculpting of a developing bone by the removal of bone is some locations with a concomitant addition in other places. Throughout bone development it is a continuous activity involving mutually dependent actions of bone-forming cells (osteoblasts) and bone removal cells (osteoclasts). Such geometric alterations are witnessed in almost all bones, irrespective of whether they form by intramembranous or endochondral ossification. Obviously, bone modelling is markedly reduced once the individual attains maturity.

2. Factors that interfere with healthy bone development

A. Hormone-related disorders Growth hormone deficiency (GHD) is a rare condition in which the body does not make enough growth hormone (GH). It’s important for parents to know that there are many reasons for slow growth and below-average height in children. At times, slow growth is normal and temporary, such as right before puberty starts. A pediatric endocrinologist (children’s hormone specialist) or primary care doctor can help find out why a child is growing slowly. Most children with GHD grow less than two inches (5 centimeters) each year.

B. Testosterone or estrogen deficiency: Testosterone is the main sex hormone found in men. It controls male physical features. The testes (testicles) make testosterone. Women have testosterone too but in much smaller amounts than in men.

C. Behaviors

  • Prolonged inactivity

  • Excessive exercise that stops menstrual cycles (in women or girls)

  • Smoking

  • Eating disorders

D.  Nutritional disorders:  Nutrition also impacts a person’s potential for height. Getting good nutrition that includes dietary sources of vitamins and minerals helps people grow. Conversely, individuals who do not get adequate nutrition may not grow as tall. Studies have found that as nutrition has improved over time, people have gotten taller. So, children that eat a diet rich in calcium, vitamin D, vitamin K2 , protein, and other nutrients will be able to maximize their potential for growth. Physical activity also plays a role in childhood growth and height, as being active promotes the release of the growth hormone. When this hormone is released, a child with open growth plates in their bones may experience more growth than they would if not physically active. However, once the growth plates in the bones close, a person will generally not grow any taller. Most females reach their full adult height between the ages of 22. Most males reach their full height by age 24. It is very unusual for a person to grow after age 24 .

3. What affects children’s bone health?

  1. The genes we inherit, our hormones, and our lifestyle all affect our peak bone mass. Genetic factors have the greatest influence on peak bone mass. To reach his or her full “genetic potential,” a child needs the right amount of certain hormones, along with healthy eating and exercise habits. 

  2. Growth hormone and the sex hormones estrogen and testosterone at puberty are essential for building bone mass in both boys and girls. 

  3. Maintaining a healthy weight and getting enough vitamin D, calcium, protein, and physical activity are also important to bone health. Calcium is the main building block of strong, healthy bones, and vitamin D helps the body absorb calcium. Other minerals, (i.e. phosphorus and magnesium) and micronutrients in amounts that are found in a healthy diet are also important in building healthy bone. 

  4. Weight-bearing exercise, such as running and jumping, helps build muscle and bone strength. Having well developed muscles is important to build strong bones. 

4. Vitamin D : Most of our vitamin D is produced when our skin is exposed to sunlight. Children get vitamin D from playing outdoors in the sun.  Our bodies’ ability to make vitamin D changes based on our location, the season of the year, time of day and whether we are wearing sunscreen or sun blocking clothing. Sunscreens block the sun’s rays that cause our bodies to make vitamin D.

We also get some vitamin D from food, but very few foods naturally contain vitamin D. In the United States, most milk, infant formulas, and some cereals are fortified (meaning vitamin D is added).

Infants need at least 400 IU (international units) of vitamin D each day. Breast-fed babies should get vitamin D supplements since mother’s milk is low in vitamin D; another option is for the mother to take high-dose vitamin D supplement. Children and adolescents need at least 600 IU of vitamin D daily.

The high percentage of the population with insufficient vitamin D concentration is worrisome and previously unexpected in sunny countries such as Cambodia. According to international studies, the amount of vitamin D generated is determined by the availability of sunlight, the intensity and zenith angle, the time of exposure, as well as the pigmentation of the skin and the percentage of body exposed. Higher levels of skin pigmentation reduce the conversion rate to vitamin D, but the amount of exposure time needed to prevent deficiency is relatively low, especially in the South East Asian latitudes.

5. What is calcium?

Calcium is a mineral with many functions. Most of the body’s calcium is stored in the bones and teeth where it supports their structure. Calcium mainly comes from the foods you eat. Good sources of calcium include dairy products (milk, cheese, yogurt); calcium-fortified products (foods and beverages with added calcium); canned fish with bones; and green, leafy vegetables. Like vitamin D, calcium is also available in supplements. Australians receive most of their calcium from dairy foods. If milk and milk-based foods are removed from the diet, this can lead to an inadequate intake of calcium. This is of particular concern for children and adolescents, who have high calcium needs. In Cambodia, milk-based food is not common. This could be a reason for calcium deficiency in Cambodian’ children and adolescent. 

6. Vitamin K:
Vitamins K2, especially MK-4, promotes bone formation by stimulating the differentiation of the osteoblast, regulating the mineralization of the extracellular matrix, upregulating the expression of the bone marker genes, and inhibiting the osteoclastogenesis. Based on these anabolic properties of vitamin k, it could be suggested that adding vitamin k as an adjunct to the bone materials may stimulate bone cells and their progenitors to produce native bone with promising results. 

References: 

  1. Smith G, Wimalawansa SJ, Laillou A, et al. High Prevalence of Vitamin D Deficiency in Cambodian Women: A Common Deficiency in a Sunny Country. Nutrients. 2016;8(5):290. Published 2016 May 12. doi:10.3390/nu8050290

  2. Akbari S, Rasouli-Ghahroudi AA. Vitamin K and Bone Metabolism: A Review of the Latest Evidence in Preclinical Studies. Biomed Res Int. 2018;2018:4629383. Published 2018 Jun 27. doi:10.1155/2018/4629383

  3. https://www.betterhealth.vic.gov.au/health/healthyliving/calcium#role-of-calcium-in-the-body

 

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