Vitamin D deficiency is linked to poor bone health. A lack of vitamin D can increase the risk of osteoporosis, especially in menopausal and postmenopausal women. In spite of the vital role of vitamin D in supporting bone health, it is often ignored.
Many people believe they only need to increase their intake of calcium to make their bones stronger. Though calcium is very important for maintaining bone health, without an adequate supply of vitamin D, it is rendered ineffective. 
That is why it is important to ensure your body receives vitamin D in high amounts in order to make the bones stronger and avoid osteoporosis. Here is a detailed discussion about how vitamin D deficiency is linked to osteoporosis.
What is osteoporosis?
Osteoporosis is a chronic condition caused due to compromised bone strength and bone thinning. It is a major health issue, especially in aging women and men. 
This disease is characterized by increased bone fragility and a higher susceptibility to fractures, particularly of the spine and hip.
Since bone loss occurs without any evident symptoms, osteoporosis is considered a ‘silent disorder’. As age increases, the deterioration in the bone density mounts and the disruption of the bone architecture continues for several years until the bones become so weak that even a relatively minor fall or bump can cause a fracture or the collapse of vertebrae.
The resulting fracture often leads to loss of mobility with 25% of patients requiring long-term care. 
Calcium and vitamin D have been recognized as essential nutrients for improving bone health, especially in menopausal women. 
How does a vitamin D deficiency trigger the development of osteoporosis?
Vitamin D plays a vital role in the maintenance of bone health. It helps to regulate the absorption of calcium in the bones. The amount of calcium the bones receive make them stronger.
Vitamin D also stimulates the process of resorption. This leads to an increased ability of the bones to preserve the calcium it has. Reabsorbing calcium helps maintain bone strength and reduces the risk of loss of bone density.
The lack of an adequate supply of vitamin D prevents efficient calcium absorption from the intestine. As a result, the bones receive less calcium even when the person is eating calcium-rich foods or using calcium supplements. The lack of vitamin D prevents the calcium from food and supplements to be absorbed into the body. This can leave the bones deficient of calcium, an essential nutrient. This is why a deficiency of vitamin D makes bones porous resulting in osteoporosis and a higher risk of fractures.
That’s not all! A deficiency of vitamin D can not only cause the loss of bone density. It may also affect bone quality by altering the way osteoblasts and osteoclasts function.
Vitamin D deficiency can also increase the production of osteoclasts, the cells that enhance the mobilization of calcium from the bones. The increased number of osteoclasts result in loss of calcium from the bones into the blood. 
Calcium from the bones is lost into the blood because the deficiency of vitamin D causes its own precursor, 1,25(OH)2D, to interact with the receptors in osteoblasts, which stimulates the formation of osteoclasts. The osteoclasts later release enzymes that break down the bone matrix, releasing calcium into the circulation. If the deficiency of vitamin D is not corrected, the absorption of calcium from the bone continues. As a result, the bones become weaker resulting in osteoporosis. 
Who is at risk of osteoporosis due to vitamin D deficiency?
- Breastfed infants are more likely to have a deficiency of vitamin D and poor bone health as breastmilk does not contain adequate levels of this nutrient
- Older people are more likely to develop vitamin D deficiency. The skin in these individuals cannot produce vitamin D when it is exposed to sunlight as efficiently as it used to when they were younger. Also, as age advances, the kidneys tend to lose their ability to convert vitamin D into its active form.
- People who have dark skin can develop vitamin D deficiency as dark skin is less efficient in synthesizing vitamin D from the sunlight.
- Patients suffering from intestinal disorders like Crohn’s disease and celiac disease that affect the absorption of nutrients, especially fats, can develop vitamin D deficiency as vitamin D requires fats to be absorbed.
- Obese people can develop vitamin D deficiency as the excess fats bind to vitamin D preventing it from getting absorbed into the blood.
- Patients who have undergone gastric bypass surgery develop vitamin D deficiency as the part of the gut that absorbs vitamin D has been bypassed.
How much vitamin D do we need?
Women need to ensure that their body receives an adequate supply of vitamin D depending on their age. The body’s requirement for vitamin D may increase during pregnancy and after menopause.
The vitamin D requirement in adult women between the ages of 19 and 70 years is about 600 IU every day. Women above the age of 70 years should receive at least 800 IU of vitamin D every day to avoid osteoporosis.
The best way to find out if a person is getting an adequate supply of vitamin D is to perform a blood test that measures the levels of 25-hydroxyvitamin D, which is the metabolized form of Vitamin D.
If the results of this test indicate levels below 30 nmol/L, it could be considered an indication of poor bone health. The levels higher than 30 nmol/L are considered adequate for adult women.
What are the best sources of Vitamin D?
Sunlight is the best natural source of vitamin D.
The dietary sources of vitamin D include cod fish oil, salmon, tuna, and swordfish. Dairy products like fortified milk, cheese, yogurt, and butter, as well as egg yolks and beef liver also offer a good amount of vitamin D.
Vitamin D is vital for the development of strong and healthy bones. The deficiency of this vital nutrient can make a person’s bones weak and porous, triggering the development of osteoporosis. Women should receive bone mineral density tests regularly to assess their bone health and ensure they receive an adequate supply of vitamin D to prevent osteoporosis and fractures.