How Hormones Affect Health


Q. What are hormones?

A. Hormones are agents produced by the endocrine and exocrine systems. Glands in the body make substances that stimulate other parts of the body. For example, insulin is a hormone, released by the pancreas. There are pituitary hormones. Estrogen is produced by the ovaries, and testosterone produced by the testes. There are hundreds of hormones. Some familiar ones are insulin, cortisone, testosterone, estrogen, and progesterone. Vitamin D is a pro-hormone, or a hormone-like substance.

Exocrine glands secrete hormones into ducts. For example, the gallbladder and the pancreas have a duct; these are part of the exocrine system. Endocrine glands secrete hormones directly into the bloodstream; these are called ductless glands. Most hormones are produced by the endocrine system. Thyroid hormone, parathyroid hormone, testosterone, and estrogen have no duct.

Two hormones are involved in bone formation. Parathyroid hormone (from the parathyroid gland) removes calcium from the bone, and calcitonin fixes calcium to the bone. They are opposing hormones and are the real workhorses in bone metabolism.

Generally, calcium and calcitonin regulatory cells are in balance. Osteoclasts and osteoblasts (cell builders) are stimulated by these two hormones, which are located next to the thyroid gland. This tricky metabolic cascade is under the influence of vitamin D, which must be present with calcium for proper bone metabolism.
Q. What is osteoporosis?

A. Osteoporosis ("porous bone") results from a lack of the calcium matrix in the bones, often as a part of aging. It is the end result of a continuum of disorders from normal bone to osteopenia (bone thinning that precedes full-blown osteoporosis). The continuum ranges from normal bone density to osteopenia to osteoporosis to fracture, representing a relative decrease in the calcium matrix of bone.
Q. How do hormones affect osteoporosis?

A. Hormones stimulate cells. Two kinds of cells are involved in the complex process of bone formation. Parathyroid hormone is produced by small glands in the neck. Parathyroid hormone releases calcium from bone, and vitamin D helps fix calcium to the bone. Calcium cannot be absorbed adequately by bone if vitamin D stores are inadequate. Many other steps are required to make bone. The osteoblasts lay down bone. Osteoclasts cause bone cells to turn over. A delicate balance is necessary for good bone formation. Bone is living tissue; we make bone, and we restore bone under the stimulation of parathyroid hormone, vitamin D, and other substances. Vitamin D does not automatically repair osteoporosis, osteopenia, or fractures.
Q. Are both women and men affected by hormonal bone loss?

A. Yes, but women are affected more often. Estrogen is very important in women's bone health; as estrogen levels fall, osteoporosis and osteopenia increase. The real difference is estrogen. Also, women usually live longer than men. Most nursing home residents are women. In nursing homes, the prevalence of osteoporosis and osteopenia is high, but the prevalence of women is also high. As for the public health aspect, osteoporosis and osteopenia are more common in women, but so is old age. Men do not have osteoporosis and osteopenia as pervasively as women do.
Q. Do any nutrients or vitamins function as hormones?

A. By definition, a hormone is a manufactured product. We can give people synthetic or natural hormones. Estrogen, thyroid hormone, and cortisone are all hormones, but they are not considered nutrients or natural. Vitamin D is actually a pre-hormone or a pro-hormone; since by definition a hormone is released by an organ in the endocrine system.
Q. In what way is vitamin D a hormone?

A. This fat-soluble vitamin is not considered a hormone, but it works with parathyroid hormones and other hormones (estrogen) to make bone and helps in the absorption of calcium.
Q. Does vitamin D help prevent cancer?

A. We are not sure, but we think so. There appears to be an association between high levels of vitamin D and a low incidence of cancer and heart disease. Conversely, low vitamin D is associated with a higher incidence of cancer and heart disease. It has not yet been shown that supplementing with vitamin D changes that risk, so the evidence right now is epidemiological.

The risk of heart disease and cancer seems to be associated with vitamin D levels, but we haven't shown that giving vitamin D will reverse the risk. Some articles mention reducing the severity of breast cancer in women and prostate cancer in men, but we cannot consider it a risk reducer. We cannot claim that if you eat mushrooms, you can lower your risk of heart disease and certain cancers.

One of the most unusual connections that has gained a lot of press lately is a possible link between vitamin D and autism. However, the government has not accepted these findings. The associations are definitely there, but we can't say that taking vitamin D lowers your risk.

Studies have not yet shown that taking 1,000 or 800 International Units (I.U.) of vitamin D lowers cancer risk. We do know that vitamin D deficiency is epidemic, and more clinicians are measuring vitamin D levels. The prevalence of vitamin D deficiency is at least 50 percent among people over 50 years of age.
Q. As we age, does our requirement for the vitamin change?

A. Definitely. As we age, the ability to convert the vitamin D precursor to active vitamin D is more difficult, and osteoporosis and fractures increase.

About six months ago, the Academy of Pediatrics raised the minimum vitamin D requirement for children to 400 I.U. per day, the same as for adults. Thus, most of us who are studying vitamin D feel that the adult level should be significantly higher, probably 800 to 1,000 I.U. per day.

The Academy was the first to realize the importance of vitamin D, and it raised the minimum for kids. It is recommended that our current standard intake of 400 I.U. daily be increased to 1,000 I.U. or more. The toxic levels would be raised quite a bit, but toxicity is another story. At least 30 percent of our population in the United States is deficient with the current level. If we raise it to 1,000 I.U. per day, that number would probably be closer to 80 to 90 percent of the population. But it is difficult get even 400 I.U. in the typical diet, but if you take it as a supplement, then you are there.
Q. What are vitamin D2 and vitamin D2?

A. There are long metabolic pathways where vitamin D is synthesized in precursors, but generally we speak of vitamin D2 and vitamin D3. There is a difference in structure between the two. There was some concern that vitamin D2 was not as effective as D3, but recent tests show that they are both utilized and absorbed by the human body, and they are both effective.
Q. Are vegetables are good sources of vitamin D?

A. No. Peanuts have only a very small level.
Q. How much vitamin D is found in mushrooms?

A. The presence of significant of vitamin D in mushrooms is a major breakthrough because it is a very-low-calorie source: 90 grams, which is one serving, has 22 calories. You would need 32 ounces of milk to get to 400 I.U., or 600 calories (30 times the number of calories).
Q. Does cooking diminish vitamin D levels in food?

A. No. Either freezing or cooking mushrooms stabilizes and locks in vitamin D. The vitamin content in raw mushrooms degrades over time, and cooking can stop the degradation.
Q. Is the vitamin D found in mushrooms similar to that which we produce from sunlight?

A. The mushroom produces D2 and humans produce D3, but otherwise they are essentially the same.
Q. Does vitamin D have any other significance to human health?

A. Studies show a link with prevention of cancer and heart disease, but the exact mechanism is unclear. In an article from a long time ago, the author identified vitamin D going back to when we were organisms coming out of the primordial stage.

If you go back trillions of years ago, we did not have the atmosphere as we have now to protect us from the ultraviolet rays or from damaging radiation from the sun. Vitamin D was established with our cells to protect our DNA [deoxyribonucleic acid] from damage by solar radiation. So our cells were created initially just to protect us from radiation. That is why the skin reacts to sunlight.

Although this is all speculative, the idea was that the vitamin was developed to protect our DNA. Who knows what else it is doing for us? It is serving in a lot of functions that we do not understand yet. So many of the vitamins we take don't have that much of an effect on us. Only two or three vitamins have proved to have a significant impact on our daily health. Vitamin D was one of those three.

We are in the infancy of vitamin D therapeutic studies. Where is this going to lead? What is the optimal vitamin D level? How much should people take?

This is a huge area and one of the hot topics in medicine right now. Vitamin D deficiency varies by geography. People in northern latitudes are at higher risk because they get less sunlight, people with darker skin and older people are also at risk. The presence of a deficiency might also depend on what country you look at in terms of the amount of fish that is eaten. My guess is that vitamin D deficiency is an international problem and is probably greater in other countries than in the United States because of generally poor nutrition.
Q. At what age is it safe to give children milk?

A. In my days of taking care of kids, we told moms not to give them so much milk. Too much milk causes iron deficiency, gas, bloating, and colic. There is no iron in milk, and typically children who drink two or three cups of milk each day are anemic. The kids need supplemental vitamin D. It is also true that mother's milk does not contain vitamin D. Regardless of the mother's vitamin D levels, the vitamin does not pass through her milk.
Q. What is osteomalacia?

A. Soft bones result from a lack of vitamin D and calcium. The fullblown disorder, which was common before we supplemented cow's milk with vitamin D, was rickets, vitamin D deficiency at its extreme. Rickets was pretty common in the 19th century, as was scurvy, caused by a lack of vitamin C. Scurvy was a bleeding disorder that affected British sailors at sea. They called themselves "Limeys" because they would take limes to prevent scurvy. The other common disorder was vitamin D-dependent rickets.
Vitamin D Insufficiency In Parkinson's Disease

Researchers from Emory University School of Medicine in Atlanta, Georgia, have proposed a role for vitamin I> deficiency in Parkinson's disease (PD). They sought to compare the occurrence of vitamin D deficiency in patients with PD with age-matched healthy controls and in patients with Alzheimer's disease (AD).

It is important to determine 25-hydroxyvitamin D [25(OH)D] levels in the diagnosis of vitamin D deficiency and, more rarely, vitamin D intoxication. Despite the name, vitamin D is a pre-hormone; it is synthesized in the body if there is adequate sunlight. Vitamin D maintains calcium and phosphate levels in the blood and has- important roles in regulating the immune system.

Researchers recruited participants between May 1992 and March 2007. Every fifth consecutively enrolled PD patient was selected from the clinical research database. Unrelated patients with AD (n = 97) and controls (n = 99) were randomly selected from the database after they were matched for age, sex, race, APOE genotype, and geographic location.

The researchers found that significantly more patients with PD (55 percent) had insufficient vitamin D levels than did controls (36 percent) or patients with AD (41 percent). The mean 25(OH)D concentration in the cohort with PD (31.9 ng./mL.) was lower than in the AD patients (34.8 ng./mL.) and in the controls (37 ng./raL.). .

This report, which involved predominantly Caucasians with PD, suggested a higher prevalence of hypovitaminosis in PD patients than in either healthy controls or patients with AD. These data support a possible role of vitamin D insufficiency in PD.
(Source: Archives of Neurology, 2008; 65:1348-1352.)

PHOTO (COLOR): "You should have come to me sooner."


An Interview with Walter Simon Newman, Jr.

Walter Simon Newman, Jr., M.D., has been on the Clinical Faculty at Stanford University since 1982. His has been Director of the Western Occupational and Environmental Medicine Association since January 2006. He is a member of the American College of Occupational and Environmental Medicine, the Santa Clara County Medical Association, and the California Medical Association.

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