Vitamin D

Vitamin D is absolutely essential for healthy bones. It is called the "sunshine vitamin" because it is made in the skin from direct sunlight. We need vitamin D to absorb the mineral calcium, the structural component of healthy bone. Vitamin D is found in fortified milk, bran cereal, tuna, shitake mushroom and egg yolk.

This is another fat-soluble vitamin with the potential for toxicity because it gets stored in the body. But new evidence suggests that we need much more than originally thought especially as we get older. 600-1000 IUs is safe and effective. Low vitamin D causes an excess secretion of parathyroid hormone (PTH). PTH stimulates calcium loss from the bone. Postmenopausal women reap the benefit from the bigger doses of vitamin D because of their high risk for osteoporosis and fractures. Vitamin D benefits your bones in two ways. It helps you absorb calcium and decreases bone calcium loss.

To get what you need from milk you need to drink a quart a day, if the milk has the vitamin D promised on the label, Several studies show the D in milk to be shockingly inconsistent and unreliable. Sunscreen has been shown to slightly decrease vitamin D absorption from the sun. Most investigators suggest you don't gamble on the sun or milk as your major source of vitamin D, but back it up with supplementation.

Excess vitamin D can induce vitamin D toxicity. E.g. Calcium deposits n soft tissues such as kidney and lung. excess vitamin A is toxic- Nausea, vomiting, headache, bone and joint pain and liver damage in the extreme. But most experts now agree that you have to take a lot more than originally thought for this toxicity - 40,000 IU.

Donna Tinnerello MS, RD, CD/N Updated August 2000

Donna Tinnerello MS, RD, CD/N is registered dietitian with more than 10 years experience in HIV and nutrition. She works in lower Manhattan at Cabrini Medical Center, the community and in private practice. Her subspecialties are cardiovascular, renal, gastrointestinal disease, diabetes and weight loss. Donna is available for private consultation by referral only.