The American Bone Health organization, says Vitamin A is a fat-soluble vitamin that is important to build strong, healthy bones.
Both osteoblasts (bone building cells) and osteoclasts (bone breaking down cells) are influenced by vitamin A. Despite its good effects, most clinical research links higher vitamin A levels with lower bone density and fractures.
Sources of Vitamin A
One source of vitamin A is retinol, found in meat and fish, fortified breakfast cereals, and vitamin supplements. Vitamin A is fat-soluble and stored in our livers. So, the liver of fish and animals are particularly rich in vitamin A.
Another source of vitamin A is beta-carotene, found in dark green and orange fruits and vegetables. Beta-carotene is generally considered safe.
According to the National Institutes of Health, the RDA is 2,330 IUs for women in the age range 19+.
Amanda A. Kostro Miller, RD, LDN, who serves on the advisory board for Fitter Living points various food sources of Vitamin A: meat, dairy, eggs, milk, butter, and canned salmon. There are also plant pigments that the body can convert into vitamin A. The pigments are called carotenoids and are found in plant-based foods like sweet potatoes, pumpkin, collard greens, turnips, winter squash, and carrots.
Vitamin A & Osteoporosis
Bansari Acharya RDN, a Registered Dietitian & Nutritionist at FoodLove.com states “Vitamin A plays a role in bone remodelling. Retinoic acid, which is a form of vitamin A that the body makes from the vitamin, suppresses osteoblasts, and stimulates osteoclasts in the bones.”
She goes on to add “However, it is crucial to obtain a balance of vitamin A and not consume in excess as higher than normal levels of vitamin A in the body have shown to increase risk of bone loss. Deficiency of vitamin A and a surplus of vitamin A can both have detrimental effects to bones. However, more research is needed to know the definitive effects of the role that vitamin A has on bone health.”
Vitamin A does not seem to directly affect calcium absorption, however during the process of bone resorption, osteoclasts release calcium into the bloodstream by attaching to the bone. Vitamin A may have a role in the stimulation of osteoclasts.
Warning
Too much vitamin A (more than 3,000 mcg or 10,000 IU/day) will give you a headache and has been linked to bone loss. Pay attention to this possibility if you eat liver or take supplements.
Watch your Meat Intake
Amanda warns “Higher Vitamin A intake from meat and dairy can lead to more bone fractures and higher risk of osteoporosis .” The possible reason behind this is that too much Vitamin A can stimulate osteoclasts, which spark bone breakdown and suppress osteoblasts, which rebuild the bone .
So, if there is more bone breakdown than bone rebuilding, then there is a high risk of low bone density.