Bone health
Within the same bone, the structure can be different depending on the part of the bone we are looking at:
- Cortical bone or compact bone: It is the outer hard part and is made up primarily of minerals such as calcium and phosphorus.
- Trabecular bone: It is known as “spongy bone” because of its honeycomb-like structure. This is the inner part of the bone; it is less dense and is interspersed within the bone marrow compartment.
Within the bone, collagen provides a framework for minerals to be incorporated and contributes to irs flexibility avoid fractures, whereas the bone minerals give the bone its strength and rigidity.
Bone remodeling
In the human body, our bones store 99% of the body’s calcium, 85% of its phosphorous and up to 60% of its magnesium. However, this storage system isn’t immovable. Bones are not inert structures within the human body, they continue to change through a process known as bone remodeling. Matured or damaged bone is removed, releasing the minerals from it to the blood, which in turn are used to create a “new” bone. This is a necessary and continuing process that occurs throughout our lifetime, and balance between the bone formation and resorption is crucial to sustain bone mass and quality.
Bone Disease
When bone formation, if modeling or remodeling don’t occur correctly, it can result in different bone diseases:
- Osteogenesis imperfecta, also known as brittle bone disease, is a genetic disorder which causes the collagen in bones to be abnormal, resulting in lower bone density and higher risk of fractures.
- Osteopetrosis, also known as marble bone disease, is a metabolic bone disease where the process of remodeling is atypical. The balance between bone being removed (reabsorption) and being created is disrupted, with more bone being created than reabsorbed. This results in an overly dense bone that breaks more easily.
- Paget’s disease is also caused by abnormal bone remodeling. In this case, bone is reabsorbed correctly, but the new bone being created is abnormal, making it prone to deformity and fractures. This disease appears in patients over the age of 40, and the root cause is unknown.
- Rickets is the softening and weakening of the bones derived from defective mineralization of part of the bones, which can be caused by genetics or, more frequently, nutritional factors. In fact, extreme and prolonged deficiency of vitamin D is the most common cause of this condition. Vitamin D helps our body to properly control calcium and phosphorus levels by promoting bone mineralization. If the body doesn’t get enough vitamin D or has problems absorbing it properly, rickets can develop.
- Osteoporosis is a degenerative bone disease that affects approximately 1 in 3 women worldwide. It leads to decreased bone density, making them more porous, fragile and less resistant and, therefore, more prone to fracture. Osteoporosis in women is more common than in men, especially after the age of 50.
Bone density
There are many factors that influence bone health and bone remodeling, including various hormones such as parathyroid hormone, calcitriol, growth hormone, glucocorticoids, thyroid hormones, and sex hormones (estrogen and progesterone). The latter play a crucial role in the development and maintenance of the skeleton, exerting a positive effect on bone mass by inhibiting resorption and stimulating bone formation through the different stages of our lives:
- Childhood: After birth comes a crucial stage for bone development because this is when the skeleton grows the most. During childhood, bones grow thanks to the presence of growth cartilage, which is where the new bone is formed. At this stage, the most active hormones are the thyroid ones, as they regulate cartilage formation, and make sure that it matures correctly. The absence or decrease of these hormones can lead to a significant growth stall (which becomes evident shortly after birth), as well as a delay in bone maturity.
- Puberty: The appearing of sex hormones eventually stops bone growth. Teenagers with higher levels of sex hormones at this stage tend to grow faster, but only up to a certain point. They gain height quickly but ultimately do not become very tall. On the other hand, teenagers with a deficit or lower levels of sex hormones do not experience a pubertal burst, and their growth is slow-going, yet it continues for a longer time. In other words, they end up being taller as adults.
- After puberty comes the bone consolidation stage. Bone growth is completed, and a person’s definitive height is acquired. Until this point, the bone has been going through formation, modeling, and remodeling. From this moment onwards, the bone will only go through remodeling.
The average person reaches their maximum amount of bone when they are between 30-35 years old. After this, there is a natural loss of bone mass over time. This is because in people over 40 years of age, the creation of new bone as part of the remodeling process is lower, resulting in decreased bone mass over time. This is caused by a decrease in sex hormone levels, which affects women more than men. In women over 50 years old, due to the decrease in sex hormones during menopause, the peak of bone mass is lower, and bone loss is accelerated compared to men. If too much bone mass is lost, it can lead to osteoporosis.
How to improve bone health
While a person’s maximum bone mass is mostly determined by genetic factors, your habits and diet can help support and maintain your bone health and density:
- Physical activity is essential for the correct bone development and promotes its formation during remodeling.
- Nutritional factors can also impact bone mass. Eating high-calcium foods throughout the day is key for your bone health, as this mineral is necessary for correct bone mineralization. The recommended amount of calcium intake can vary depending on age and gender.
- Vitamin D also plays an important role in bone mineralization, as it helps your body absorb calcium. The main way to obtain this vitamin is through sunlight exposure and food sources such as fatty fish, liver and cheese.
But remember! No excess is good for you. Bone health requires a balance between old bone reabsorption, and new bone creation. That means, a surplus of any of these factors can be contra productive, or even lead to other health concerns.