Vitamin D is required for healthy, strong bones and calcium absorption. Limited research suggests that vitamin D might also protect the kidneys. Continue reading to learn about its role in bone and kidney health.
Vitamin D for Bone & Kidney Health Snapshot
- Required for bone health and calcium absorption
- May prevent osteoporosis in older adults, along with calcium
- Supplementation likely improves bone health in the elderly who are at a higher risk of deficiency
- Insufficient evidence for kidney protection
Vitamin D is a fat-soluble vitamin the body needs to build and maintain strong bones. It helps absorb calcium in the gut, keeping calcium and phosphorus in balance to mineralize bones .
Without enough vitamin D, bones can become thin, weak, brittle, or misshapen. Getting enough vitamin D prevents rickets in children and osteomalacia in adults. Along with calcium, vitamin D also helps protect older adults from osteoporosis .
The body naturally makes vitamin D when exposed to sunlight. Getting regular, moderate sun exposure is a safe way to maintain normal vitamin D levels during the summer months.
Vitamin D is also found in certain foods, such as fatty fish like salmon and sardines. Additionally, many vitamin D supplements are available on the market.
Many older adults don’t get enough vitamin D from sunlight. The elderly also tend to have poor vitamin D absorption, which puts them at a higher risk of deficiency. Taking a supplement with vitamin D may be beneficial for bone health in such cases .
There is insufficient evidence to recommend vitamin D for kidney health, though early research findings are promising.
Taken at the recommended doses, vitamin D supplements are considered safe. However, taking too much can be harmful. Vitamin D supplements may also interact with prescription medications. Remember to talk to your doctor before supplementing!
Vitamin D Improves Bone Health
Vitamin D maintains calcium and phosphorus balance in the body. Specifically, it promotes calcium and phosphorus absorption from the gut, calcium reabsorption in the kidney, and calcium mobilization in bone [2, 3, 4].
Additionally, vitamin D suppresses parathyroid hormone and reduces bone degradation, thus indirectly increasing bone mass [5, 6].
Bone cells also use vitamin D to grow and remodel bones. In turn, vitamin D regulates the growth and function of bone-building cells (osteoblasts) [7, 8].
However, in cell-based studies, higher doses of this vitamin stimulate cells that degrade bones (osteoclasts) due to its narrow therapeutic range. This further emphasizes the importance of taking vitamin D at the recommended doses [6, 9].
Vitamin D Prevents Rickets and Osteomalacia
Vitamin D deficiency causes rickets in infants, young children, and adolescents and osteomalacia in adults [10, 11].
Rickets is characterized by a delay in the mineralization of growth cartilage. Bones soften over time and become deformed, leading to growth retardation, enlargement of the epiphyses of the long bones, and leg deformities [11, 12].
Maternal vitamin D deficiency can affect the skeletal development of fetuses. In a study of 424 pregnant women, mothers with a deficiency were more likely to have fetuses with femoral bones that had rachitic features .
Osteomalacia is an absence or delay in the mineralization of newly-formed bone collagen. Adults with osteomalacia may experience global bone discomfort, and muscle aches and weakness [12, 14, 12].
Osteomalacia and rickets attributable to vitamin deficiency are preventable with an adequate nutritional intake of this vitamin. Varying doses and treatment regimes have been described with the aim is to achieve a blood level between 20 and 50 ng/mL .
Vitamin D Prevents Osteoporosis and Fractures
Low blood levels of vitamin D are associated with lower bone mineral density, mineralization defects, and an increased risk of bone loss or fracture in both men and women [16, 17, 18, 19].
This vitamin should be considered for the therapy of osteoporosis, alone or in a combination with other therapeutic bone agents [20, 21].
Studies show that in adults aged 50 years or older, vitamin D supplementation in combination with calcium has beneficial effects on bone mineral density, osteoporotic fractures and falls without evidence of harm [22, 23, 24].
In elderly women that were given 1,200 mg of calcium and 800 IU of vitamin D3 daily for 3 years, the risk of hip fracture was reduced by 43% and the risk of fractures, in general, was reduced by 32% .
Populations that shield themselves from the sun or who have dark skin, African American and Hispanic men, may be at elevated risk of vitamin deficiency and fractures [26, 19].
However, the annual administration of high doses of vitamin D (500,000 IU) resulted in an increased risk of falls and fractures in older community-dwelling women .
Vitamin D & Kidney Health
Chronic kidney disease patients have a higher prevalence of vitamin D deficiency compared to the general population .
Supplementation decreases elevated calcium levels in chronic kidney disease patients thus preventing multiple organ dysfunction [29, 30].
Studies suggest that vitamin D deficiency or insufficiency is frequent after renal transplantation .
The VITALE study (VITamin D supplementation in renal transplant recipients) showed that high doses of vitamin D prevent posttransplant bone loss without causing adverse events .
According to other studies, vitamin D prevents kidney damage in sepsis-induced acute kidney injury [33, 34].
In one study, it protected patients with diabetic kidney disease from kidney injuries .
Despite these promising findings, more large-scale studies are needed before vitamin D can be routinely recommended for people with kidney disease.
Along with calcium, vitamin D is required for maintaining strong and healthy bones in both children and adults. Vitamin D also helps absorb vitamin D in the gut, which aids bone mineralization. Vitamin D deficiency weakens the bones. It can cause rickets in children and osteomalacia in adults. People who can’t get enough vitamin D from sunlight and food may need to consider supplementing to maintain healthy bones. Studies revealed that the elderly are at an increased risk of deficiency since they absorb less vitamin D. Limited evidence suggests that people with kidney disease are more prone to vitamin D deficiency. However, solid evidence is lacking to support vitamin D supplementation in kidney disease patients.
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