Medicine For People!

February 2004

  • Vitamin D -- A Cornerstone of Health
  • Rant 'O the Month - Five Minutes to Redemption
  • Monroe Street Clinic News - Operating on Trust

Vitamin D - a Cornerstone of Health

Part One of a Two Part Series

Vitamin D is one nutrient you've heard about since first grade. You know you can get it from sunshine and you know it prevents rickets. You may not know, however, that vitamin D may also prevent some cancers, osteoarthritis, multiple sclerosis, and hypertension, that it can strengthen the immune system and increase muscle strength. And you may not know that people living in temperate and northern climates are at grave risk of being deficient in Vitamin D.

Vitamin D from the Sun

Technically, vitamin D is not a vitamin but a hormone that our bodies can make under the right conditions. When the right kind of light hits our skin, our bodies produce vitamin D from a form of cholesterol. If you are a young white male and you strip naked on a beautiful sunny summer day, your skin can manufacture 20,000 units of vitamin D within minutes.

However, you can't count on an outdoor walk to give you enough vitamin D, especially in the Pacific Northwest. When sunlight passes through too much of the atmosphere, the ultraviolet light is filtered out. At higher latitudes (especially during the winter), and when the sun is lower in the sky in the earlier morning and later afternoon, we don't make much vitamin D. When farmers were told to apply sunscreen to prevent skin cancer, they turned up vitamin D deficient at the end of the summer, the time of year they should be highest in vitamin D. Sunscreen with an SPF of only 8 reduces skin production of vitamin D by almost 98%.

Other factors also affect vitamin D production. As we age, our skin contains less cholesterol, so that an older person in a tanning bed will produce only 25% of the vitamin D a young healthy adult will. Overweight people generally have about one-third the circulating vitamin D of a person of normal weight. The theory is that their fat cells soak up most of the vitamin D they eat or produce. If our skin is darkly pigmented, we may make only 1% of the vitamin D of a light-skinned person.

Vitamin D under a Microscope

Let's look again and see what happens at a cellular level. Ultraviolet light (UVB) hits the skin and interacts with a relative of cholesterol called ergosterol, producing cholecalciferol. (The term combines "chole" for cholesterol with "calci" for calcium, because cholecalciferol helps with the absorption of calcium.) Cholecalciferol rides the bloodstream to the liver where it turns into calcidiol [25(OH)D]. After that it makes a quick trip to the kidneys, which transform it into calcitriol. The kidneys excrete calcitriol into the blood to help regulate calcium in the body. You can see pictures of the molecular form and read more about the science at this University of California webpage.

Although we can make our own, we in northern climes depend on outside sources to get enough vitamin D to meet our needs. Commercial vitamin D comes in two different forms.

  1. Vitamin D2 (ergocaliciferol) is made from plant products and added to milk.
  2. Vitamin D3 (cholecalciferol) is the form that animals, including us, can manufacture in our skin from pre-cholesterol. Lacking sunlight, we can obtain cholecalciferol from animal products and from cod liver oil.

Cholecalciferol (Vitamin D3) is the best form of supplemental vitamin D to take.

We'll have more to say about who should take Vitamin D and how much next month in the second part of this Two-Part Series, but first we want to tell you about the amazing thing this substance does in your body.

Making Genes Talk

It was evident a long time ago that people who got a great deal of sun exposure developed skin cancer more frequently. In 1936, someone looked at the map and the records of cancer prevalence, and noted something unusual. People who lived in sunny parts of the country, though they got more skin cancer, got less cancer in other parts of the body than their northern cousins.

As the years went on, it became clear that vitamin D lay behind this. For example, if you look in the blood of groups of people, you find that the higher their vitamin D level, the less colon cancer they get.

Why is this? On the deepest level, vitamin D is vital to gene expression. We all know that our genes are made of molecules of DNA that reside inside each nucleus, and that our genes contain the instructions for building our bodies and operating our physiology. Now, if the DNA in a cell in my little finger has the instructions to build an elbow (and it does have those instructions), why isn't there an elbow at the end of my little finger? The reason is that the cell somehow "knows" which part of the DNA it needs to read and process. Scientists call this "gene expression."

Vitamin D plays a key role in regulating gene expression. The genes it regulates are involved with blood pressure, with bone strength, with the orderly growth of cells, and with other vital functions.

Vitamin D prevents some cancers and not others

Remember, now, that the vitamin D made in our skin is useful only after it has been transformed into calcidiol in the liver. Next, under careful regulation by the parathyroid gland, the kidney transforms this stage of vitamin D into a measured amount of its final, active form, calcitriol. From thence, calcitriol travels about the body for use in other tissues.

The late-breaking news is that breast, prostate, and colon tissues can also transform calidiol into calictriol, So, if you live in the sun, you have more calcidiol floating around, and your colon, breast, and prostate (as applicable) will make more calcitriol. And this extra calcitriol reduces the tendency of those cells to divide abnormally. The result is that...

Vitamin D Prevents Colon Cancer

Cancer is the result of abnormal gene expression, an expression of the genes that tell a cell to multiply when it should not. In the 1980, a study followed 25,000 people for more than ten years to see who would develop colon cancer. The study found that people with acceptable levels of vitamin D had one-third the risk of developing colon cancer. Those whose systems had optimal (more than just "acceptable") levels of vitamin D had 80 percent less risk. For more about the study, click here. A subsequent study at Dartmouth Medical School found that both calcium and vitamin D reduced the rate of colon cancer. For more information, click here.

Prostate Cancer

Prostate cancer is less likely in men who consume more vitamin D. In fact, prostate cancer cells multiply more slowly or may even regress in the presence of vitamin D. No, don't stop seeing your urologist if you have prostate cancer, but do get your vitamin D level checked to be sure you have enough of it. (An optimal level of vitamin D, measured as calcidiol, is 50 nanograms per milliliter of blood.)

Osteoporosis

Osteoporosis is common, as is vitamin D deficiency. It may even be that osteoporosis is the result of years of marginal vitamin D deficiency. Osteoporosis is usually not due to a lack of calcium in the diet. The Chinese consume less calcium than we do, yet have less osteoporosis. Moreover, older people may have little calcium in their bones, but they have plenty where it shouldn't be, such as in the joints and blood vessels. The reason the Chinese have less osteoporosis on a lower calcium diet is that the western diet, rich in processed and heavy foods, is higher in phosphorus, which pulls calcium and magnesium out of the body. So we in the West have a higher calcium and magnesium requirement than people who eat a simpler diet, and we may run short. If you look at the research, most of it shows that without added vitamin D, calcium supplements do not improve bone strength. We need vitamin D to lay calcium down in the bones.

Vitamin D and Pain

Dr. Plotnikoff, of the University of Minnesota Medical School, measured vitamin D levels in 150 patients who came to an outpatient university clinic with nonspecific musculoskeletal pain. Among Black, Hispanic, East African and American Indian patients with chronic pain, 100 percent were vitamin D deficient. Add in Caucasians and others, and ninety-three percent were vitamin D deficient, with young women in their childbearing years being at the greatest risk for misdiagnosis or delayed diagnosis. Dr. Plotnikoff (along with co-author, B.A. Quigley) recommended that screening for vitamin D levels become standard practice in all such clinics. (Plotnikoff, GA and Quigley BA; "Prevalence of Severe Hypovitaminosis D in Patients With Persistent, Nonspecific Musculoskeletal Pain"; Mayo Clin Proc. 2003:78:1463-1470.)

Making sure our systems are replete with vitamin D may be a first step in dealing with chronic nonspecific pain.

High blood pressure

Our kidneys make renin, a substance that regulates blood pressure. Too much renin, and the blood pressure rises. Drugs such as Zestril(lisinopril) and others of the ACE inhibitor family (the names of all drugs in this class end in "-pril") interfere with this effect of renin. Elevated renin levels also increase the tendency to diabetes. The good news is that vitamin D suppresses renin production, which reduces the risk of high blood pressure and diabetes. To read more, click here.Vitamin D is more likely to lower excessively high blood pressure in a person with low vitamin D levels.

Ever since I was in medical school, doctors have been asking why African Americans are more prone to severe hypertension. Maybe it is because their dark skin is perfect for equatorial sun but does not allow adequate production of vitamin D in northern climes, resulting in a higher renin level and higher blood pressure.

Falls in the elderly

Older people are likely to become vitamin D deficient. One result is an increased tendency to fall and break bones, not just because the bones are weak but also because muscles are weaker and balance is poorer. An Australian study of 1500 women found that almost half of the women in high-level residential care facilities and about a fifth of the women in low-level care were severely deficient in vitamin D. Supplemental vitamin D doubled their vitamin D levels and reduced the risk of falling by 20 percent. Read more about the study at New Scientist.

Multiple Sclerosis

If you plot the incidence of MS on a map of the world, you'll find higher numbers of people with MS in higher latitudes where sunshine is less. Further, if you then treat those people with vitamin D, you'll see some improvement. Is MS due solely to vitamin D deficiency? No one is suggesting that at this time.

Next Month

The more researchers study vitamin D, the clearer it becomes that having adequate levels could prevent a host of health problems and save millions in health care dollars. Why, then, are deficiencies rampant? Why aren't people aware of their need for this important nutrient? And how can each of us make sure make sure we have enough to take care of our needs? We'll delve into these issues and more in next month's newsletter.

Rant 'O The Month - Five Minutes to Redemption

Do we really need scientific studies to tell us that children watching television is a recipe for poor health? If we do, we are in trouble, because as usual there are people who will do anything to get brownie points, including writing "scientific" papers showing that television does no harm.

Phooey! Television watching does children major harm. An article in a 1990 issue of the journal Pediatrics summarized the issue thus. "Children's TV viewing can be a parent's nightmare -- not just because of what they watch, but when. Watching television at bedtime can cause sleep disturbances in children. Those children who watched the most television daily, and those who watched television at bedtime, were the most likely to have sleep disturbances including bedtime resistance, difficulty falling asleep, anxiety around sleep or shortened sleep duration. In particular, the presence of a television set in the child's bedroom may be a relatively under recognized, but an important, contributor to sleep problems in school children. About 25% of children had a TV in their bedroom. On average, children watched about 2 hours of television on weekdays, with about 5.8% watching 4 or more hours each weekday. On weekends, kids watched close to 3 hours of television on average, the study results show. American children spend about 25 hours a week watching television. That is almost as much time as they spend at school. Children who watch the greatest amount of television may be more likely to be obese, have poor eating habits, lead sedentary lifestyles, perform poorly in school, and be less socially active than children who watch less television. Exactly how television viewing affects sleep is unknown, but perhaps it may simply serve to displace sleeptime, thus shortening sleep duration to unacceptable limits or the time spent by the child in front of the box may substitute for physical activities, such as playing outside and engaging in sports activities, resulting in poor quality sleep."

For those of you who are not doing well on your New Year's Resolutions,here is your chance for redemption. It will only take you FIVE MINUTES. Take that TV out of your child's room. Disconnect your cable and TV antennae. You and your child will benefit from getting to know each other better, from getting outside more, and from developing other skills aside from using a remote control. Just do it. Now.

Monroe Street Clinic News - Partnership of Trust

Washington State has one of the higher malpractice insurance rates in the nation. Recently, our insurance broker informed us that our 2004 premium would be $73,080. I cannot continue to give you good service at a reasonable price and pay this kind of premium.

As you will remember from last year, our premiums have been rising steadily so this has not come as a surprise. Having considered a number of options, I have decided to continue in practice here without liability coverage. This is where my heart is.

What does this mean to you as a patient? Two things. First, on your next visit, we will ask you to sign a new registration form agreeing to arbitration in the event you have a claim against us for negligence. Second, I'm asking you to take a special responsibility. If you ever have reason to believe our treatment is causing problems, please let us know right away, so we can support both your health and safety as well as your peace of mind.

While I would rather not be breaking this particular ground, I trust that it will turn out for the best. I understand, however, that you may feel differently. If this new system is not agreeable to you, please let us know and we will forward your medical records to the physician of your choice.


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Medicine for People! is published by Douwe Rienstra, MD at Port Townsend, Washington.