Vitamin A Toxicity and Osteoporosis

The highest incidence of osteoporotic fractures in humans is in Northern Europe, where dietary intake of vitamin A is unusually high. The average dietary intake of vitamin A in the Swedish adult population is 1.3 to 1.6 milligrams per day. And in Norway, intakes can average 1.5 to 2.0 millgrams per day. As a result, researchers studied a group of 422 women in Sweden, between the ages of 28 and 74 years. interestingly, they found that vitamin A intake was negatively associated with bone mineral density. In other words, for every 1-milligram increase in daily intake of dietary retinol, the risk of hip fractures increased by 68 percent. When comparing intakes greater than 1.5 milligrams per day to intake less than 0.5 millgrams per day, those with higher intakes had 10 percent less bone mineral density in the neck, 14 percent less at the lumbar spine, and 6 percent less for the whole body. Additionally, the risk of hip fractures was doubled in the higher intake group. The researchers concluded that consuming double the recommended daily amount of vitamin A may dramatically increase the risk of osteoporosis.