Vitamin D and Bone Status in Factory Workers. – Dr. Gary’s Nutritional Library

Vitamin D (VD) is necessary for normal use of calcium by the body, including mineralization of bone. The blood test for VD in the body is serum 25-hydroxyvitamin D (S-25OHD.) Adequate intakes of calcium and of VD are necessary to maintain normal parathyroid activity, as tested by serum intact parathyroid hormone (S-iPTH) levels.

The daily dose of VD suggested for people with darker skin and the elderly is 1000 IU. S-25OHD levels for beneficial bone effects in the elderly are 70 to 95 nmol/l. In adolescence, the beneficial level is over 50 nmol/l. When calcium is not available, the S-iPTH levels can become elevated, called ‘secondary hyperparathyroidism.’

Women have 4 times the risk of developing osteoporosis as do men. The problem increases with menopause and the loss of estrogens. The problem is in developed and developing countries. “A high adult peak bone mass is protective against late-life osteoporotic fractures.” Osteoporosis prevention hinges on developing a maximum peak bone mass in the early decades of life through good nutrition, adequate vitamin D intake, and exercise.

The garment workers of Bangladesh are mostly women who work indoors for many hours, seven days a week. When they are in the sun, they are usually covered with clothes, except for face and hands. There are 1,600,000 garment workers in Bangladesh. They have a poor intake of calcium and often develop osteoporosis or osteomalacia young.

Two hundred women were selected for this study of vitamin D status. Blood tests were done of S-25OHD, S-iPTH, serum calcium, serum phosphate, and alkaline phosphatase. Bone mineral density (BMD) studies were done of the head of the femur and the lumbar spine. This study defined low S-25OHD as being below 25 nmol/l. Secondary hyperparathyroidism was S-iPTH above 65 ng/l.

The subjects were divided into four groups. One treatment group received 10 microgm. VD, daily. Another treatment group received 10 microgm. VD and 600 mg. Ca as Ca-lactate. Another treatment group received multiple micronutrients, 10 microgm. VD, and 600 mg. of Ca as Ca lactate. The last group was a placebo group. (The micronutrients included copper, zinc, selenium, and iron.)

Of the 200 workers, 135 completed the 12 month trial. Twenty-two workers had VD deficiency with a level below 25 nmol/l at the start. At the end of the year, 7 people in the placebo group were VD deficient and none of the people in the treated groups were deficient. In the people with high S-iPTH levels, those supplemented had a drop in the S-iPTH levels. The study indicates that, when S-25OHD levels go below 40 nmol/l, the S-iPTH levels begin to rise.

All supplemented groups showed increased BMD in the femoral neck compared to the placebo group. There were no significant changes in the lumbar spine.

CONCLUSION: In general, Americans are advised to take 1000 IU daily of VD supplementation if they are not exposed to UV light, have dark skin, or are elderly. This study supports the use of VD supplementation in premenopausal women who work indoors, such as in Bangladesh. The goal is to reduce bone disease. Supplementation caused increased BMD in the femoral neck.

NOTE: Read Summary #045 about the influence of secondary hyperparathyroidism on other disease processes. Read abiyt itger duseases caused by vitamin D deficiency.