Biochemistry

A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms

A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. The negative pole is near the oxygen atom and the positive pole is between the hydrogen atoms.

Vitamin D has been a rising star in the Vitamins Hall of Fame. Recent research indicates that Vitamin D is essential not just for healthy bones and teeth, but it is good for the heart, brains and lungs. Some studies show that it plays a role in controlling pain. Vitamin D deficiencies are becoming more common as most people work inside and are less exposed to the sun. Even when we do venture out in the sun, we usually apply a sunscreen lotion to prevent the sun's rays from penetrating the skin. People living in higher latitudes may not receive enough exposure to the sun. The elderly who are housebound may also suffer from deficiencies of Vitamin D. An adult would require about 800 IUs a day. We can usually get 400 IUs from diet alone, the rest can be through quality Vitamin D supplements.

The hormonal functions of vitamin D include regulation of bone health, regulation of muscle health (including both skeletal and heart muscle), regulation of immune response, regulation of insulin and blood sugar, and regulation of calcium and phosphorus metabolism. Because vitamin D receptors (VDRs) are in so many different tissue types-including your brain and skin-vitamin D deficiency may contribute to many human diseases including depression and autoimmune diseases, and may increase risks of deadly cancers, cardiovascular disease, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes.

• Regulation of bone health, calcium, and phosphorus: Your bones comprise many different substances, including collagen proteins, keratin proteins, and the minerals silicon, boron, and magnesium. But the two most critical bone components are the minerals calcium and phosphorus, which make up over half of all bone composition. While bone health is regulated by many different substances in the body-including growth hormone, testosterone, and estrogens-the importance of calcium and phosphorus in bone health also points to the special importance of two bone health regulators: parathyroid hormone (PTH) and vitamin D. Your parathyroid glands secrete PTH whenever your blood calcium level gets too low. When that happens, PTH triggers release of calcium from your bones in order to boost your blood level back up to normal. PTH also triggers your kidneys to retain more calcium (keeping it available for your bloodstream) and excrete more phosphorus (thereby helping to create a more favorable ratio of calcium to phosphorus in your blood). If there is too much PTH released from your parathyroid glands, however, you may end up removing too much calcium from your bones and leaving too much in your blood, compromising both your cardiovascular health and your bone health. Vitamin D deficiency is a key risk factor for overproduction of PTH, and optimal levels of vitamin D are associated with healthy parathyroid function and desirable PTH levels. Like PTH, vitamin D helps your intestines absorb more calcium from your food, and it also helps your kidneys hang on to calcium. But unlike PTH, vitamin D also helps your kidneys retain phosphorus. The two hormones work together in order to assure proper balances of calcium and phosphorus in your bloodstream and in your bones. PTH also triggers the conversion of hydroxyvitamin D into dihydroxyvitamin D (the hormonally active form).
• Regulation of immune function: Vitamin D plays a critical role in rheumatoid arthritis, multiple sclerosis, Crohn's disease, systemic lupus erythematosus, and numerous other autoimmune conditions. There are vitamin D receptors (VDRs) on your immune system's macrophage and dendritic cells. When triggered by vitamin D, macrophage cells are capable of releasing antibacterial peptides (parts of protein) like cathelicidin, and these antibacterial proteins play a critical role in your immune system's prevention of infection, including tuberculosis and leprosy. Vitamin D deficiency is a risk factor for these diseases.
• Regulation of blood pressure and cardiovascular health: Vitamin D plays a direct role in regulating your blood pressure by inhibiting the activity of a system called the renin-angiotensin system, which helps increase your blood pressure whenever it gets too low. The renin-angiostensin system increases your blood pressure by helping your body retain sodium and water (providing more fluid in your blood vessels) and by causing your blood vessels to constrict, thereby increasing the pressure inside them. You need optimal levels of vitamin D to hold this system in check, and to prevent it from raising your blood pressure under inappropriate circumstances. Vitamin D deficiency is a significant risk factor for high blood pressure, including during pregnancy (pre-ecclampsia). When vitamin D is deficient in your body and PTH is released in inappropriately large amounts, too much calcium can accumulate in your cells. Too much calcium in your heart tissue is a problem associated with increased risk of oxidative stress and tissue damage. The ability of heart tissue to heal after an event like heart attack depends on an optimal amount of vitamin D.
• Regulation of insulin and blood sugar: Vitamin D plays an important role in the regulation of insulin metabolism and blood sugar balance. Vitamin D deficiency is a risk factor for developing type 2 diabetes, and vitamin D levels have been associated with insulin secretion by the beta cells of the pancreas as well as insulin activity after it's released into the bloodstream. When vitamin D deficiency leads to release of large amounts of PTH, too much calcium can accumulate in your cells. When too much calcium accumulates in fat cells, they can produce too much cortisol, a hormone that counteracts the effectiveness of insulin. Similarly, too much accumulation of calcium in your fat and muscle cells can inhibit the formation of a protein called GLUT-4, which helps carry sugar (glucose) out of your bloodstream and into your cells, whenever insulin directs it to do so. Without sufficient vitamin D, too little GLUT-4 is formed, and insulin lacks one of the tools it needs to do its job.
• Regulation of muscle composition and muscle function: Vitamin D deficiency plays a key role in preventing muscle weakness and falls, especially in older adults. Vitamin D deficiency is associated with too much accumulation of fat throughout muscle tissue, in such a way that muscle strength is decreased and physical performance is compromised, independent of muscle mass. Because vitamin D is a key regulator of calcium metabolism, and calcium is known to play a key role in nerve firing and nerve triggering of muscle contraction, vitamin D may have a broader role in reducing risk of falls.
• Prevention of cancer: Vitamin D regulates several genes and cellular processes related to cancer progression, and vitamin D provides powerful protection against common cancers, including bladder cancer, breast cancer, colon cancer, ovarian cancer, prostate cancer, and rectal cancer. About 75% of women with breast cancer are vitamin D deficient. A 2009 analysis revealed that women in the highest vitamin D range reduced their risk of breast cancer by 45%. Another 2009 review found that sufficient vitamin D levels were associated with reduced risk of colorectal cancer. Even after diagnosis with colorectal cancer, higher vitamin D levels are associated with reduced mortality. Cancers of the prostate, pancreas, lung, and endometrium are also associated with vitamin D insufficiency.