Nina Laidlaw Rumler, B.A.Headlines about vitamin D abound. Is it as good as they say? How does it impact exercise and athletes?Advocates claim a wide range of proven or implied benefits, such as: Improved physical performance Bone strengthening (rickets, osteoporosis, osteomalacia, gum/tooth diseases) Strengthening of the immune system –fewer colds, flu, pneumonia, allergies. Inhibition/prevention of hypertension, diabetes, rheumatoid arthritis, lupus, multiple sclerosis, cancer, heart dis...