Chapter 9

Looking at Other Possible Functions of Vitamin D

In This Chapter

Looking at vitamin D’s role in asthma

Identifying a link between vitamin D and psoriasis

Examining vitamin D’s effect on the brain

Managing weight with vitamin D

Exploring vitamin D’s role in fibromyalgia

In the past few chapters, I’ve discussed some of the most common diseases, from heart disease to diabetes to cancer, and how growing evidence links these diseases to vitamin D. In this chapter, I discuss several other conditions and diseases that may be linked to lack of vitamin D. If even a small fraction of the information in these chapters proves to be true, it would revolutionize the field of medicine.

It’s important to remember the following points as you read this chapter:

The evidence is contradictory as to whether vitamin D makes a difference in these diseases.

Given our knowledge of the biological effects of vitamin D, we don’t know how it might play a role in several of these diseases.

The positive effect of directly raising vitamin D levels in these diseases has not been studied yet.

If vitamin D is so essential to human health and getting enough vitamin D is so easy, then no one anywhere should be deficient. Yet statistics show that a large number of people don’t reach the recommended levels (serum 25-hydroxyvitamin D of 20 ng/ml or 50 nmol/L), especially in winter.

In subsequent chapters, I show you how to get enough vitamin D while avoiding future visits to a dermatologist for skin cancer. In this chapter, I present some other important diseases and the role vitamin D may play in their prevention and treatment.

Finding a Role for Vitamin D in Asthma

Asthma is a common condition in the United States and throughout the world. Seven percent of Americans, about 22 million people, suffer from asthma. A third of them are children. Asthma can be severe but, fortunately, deaths from asthma amount to only about 3,450 per year. Epidemiological evidence suggests that vitamin D may play a role in preventing asthma.

Reviewing asthma

The major symptom of asthma is difficulty breathing, usually as a result of spasm of the breathing tubes in your lungs, the bronchi. This condition is called bronchospasm. Symptoms can vary from mild to severe. When bronchospasm occurs, it is called an asthma attack and displays the following symptoms:

Chest tightness

Cough

Shortness of breath

Wheezing upon breathing out

As an asthma attack worsens, its severity is determined by having the patient breathe hard into a tube and measuring the flow of air. Air flow continues to lessen if the attack isn’t broken, until the patient is exhausted and may even require help to breathe. The face and fingernails may turn blue from lack of oxygen, and in severe attacks a person can die from hypoxia (oxygen starvation).

Several factors in the environment can trigger an asthmatic attack. The most important are listed here:

Cigarette smoke

Cold air

Poor air quality due to pollution, including dust, animal hair, molds/mildews, and perfume

Psychological stress

Viral respiratory infection

Hereditary factors are at work, too. Researchers have found variations in more than 30 genes that contribute to asthma.

Asthma is also more prevalent in lower socioeconomic classes, and deaths due to asthma tend to occur in those populations. This is probably because they confront more of the triggers for an attack and they’re less likely to have adequate health care. Oddly enough asthma is also more prevalent in athletes. They experience asthma attacks during exercise, probably because of drying of the airways or in response to the rush of air during exertion.

Asthmatic airway obstruction is reversible. The obstruction results from a combination of spasm and inflammation often associated with infection. An asthma attack may be prevented by using inhaled drugs like steroids or bronchodilators. Steroids improve the inflammatory part of the problem, and bronchodilators prevent the bronchospasm. The trouble with inhaled steroids is the side effects, some of which are limited to the mouth and others can affect the whole body. For example, inhaled steroids can cause a yeast infection of the mouth called thrush. Inhaled steroids can also cause osteoporosis, weight gain, diabetes, and high blood pressure, but the risk of these side effects is much lower than if you take steroids by injection or as a pill.

If a person avoids triggers such as cigarette smoke and animal hair, they can prevent asthma attacks. They may still carry rapid-acting bronchodilators for an acute asthma attack, but they’ll need them less often.

Half the children with asthma will grow out of it, perhaps because of a change in environment. Those who don’t can control their asthma with inhaled steroids. Many patients often don’t require medication until an infection or other trigger brings on an attack.

The prevalence of asthma is increasing greatly. In the United States, the incidence among children rose from 3.6 percent in 1980 to 9 percent in 2001. Asthma is much more a disease of the city than the countryside.

Understanding the role of vitamin D

Evidence of an important role for vitamin D in preventing and treating asthma is promising but is based mostly on associations between serum 25-hydroxyvitamin D and various aspects of the disease. Medical researchers know that these types of associations may not hold up under more careful scrutiny. So, although this is interesting, it isn’t yet up to the high standard needed to make public health recommendations.

Some studies in mice show the role of vitamin D in asthma isn’t simple and straightforward. Mice that lack the vitamin D receptor do not develop experimental asthma — this suggests that calcitriol (active vitamin D) is necessary for the normal pathogenesis of asthma. This fits with several cell and animal studies that show calcitriol works with the vitamin D receptor to increase the number of T cells that are normally responsible for an asthma attack.

So whereas that suggests vitamin D would be bad for asthma, there are other studies that show it would be helpful. Another study showed that treatment of mice with calcitriol made them respond better to anti-inflammatory asthma treatment. That would suggest vitamin D might be a good complement to other treatments.

Also cell studies show that calcitriol has beneficial effects on the smooth muscle cells of the airways — if this also happens in the body, then calcitriol might block or slow the type of changes to the lung that develop in advanced asthma.

If we jump all the way to studies that associate serum vitamin D levels with asthma, there’s also a lot to be excited about. Some examples are

People with high UV light exposure have low rates of asthma.

Among adults, obese African Americans have the highest rate of asthma in the population and the lowest levels of vitamin D.

Asthmatic people with low levels of vitamin D perform worse on lung function tests than those with normal levels of vitamin D.

Higher vitamin D intake in pregnant women is associated with up to 40 percent lower asthma rates in their offspring.

Vitamin D levels in asthmatic children are inversely associated with markers of asthma severity in children. They have fewer visits to the hospital, and they need anti-inflammatory medication less often.

Several studies were started in the last few years that aim to evaluate the effect of vitamin D supplements on the development or severity of asthma. Still, there’s no reason to wait to increase your vitamin D intake if you have serum 25-hydroxyvitamin D levels less than 20 ng/ml or 50 nmol/L. Doing that will at least benefit your bones and may help your lungs as well.

Treating Psoriasis

People who suffer from psoriasis have known for hundreds of years that exposure to the sun improves this condition. What they didn’t know until recently was that the skin production of vitamin D from sun exposure was responsible for the improvement. This is using vitamin D as therapy, not for prevention; however, there’s no evidence that you can take large amounts of vitamin D as a pill and get the same benefits as UV light or a topical form of vitamin D.

Reviewing psoriasis

Psoriasis usually begins between the ages of 15 and 25, but it can occur at any age. Psoriasis is an autoimmune skin disease that consists of red, scaly patches that have a silvery-white appearance. These so-called psoriatic patches occur on the elbows, knees, scalp, genitals, palms of the hands, and soles of the feet. Some people have more extensive disease that covers the entire body. The patches itch and can be painful.

The psoriatic patches make up 90 percent of cases, but another, pustular form consists of raised bumps that contain pus but no bacteria. In the nonpustular form, the patches of disease, called psoriatic plaques, tend to occur where the skin is scratched or otherwise injured.

Psoriasis tends to improve and then recur irregularly, making it difficult to know whether treatment is helping. The condition is graded as mild if it affects less than 3 percent of the body, moderate if it affects more than 3 percent to 10 percent of the body, and severe if it affects more than 10 percent of the body.

The cause is unclear, but psoriasis seems to have immune characteristics because T cells and cytokines (see Chapter 5) are involved in addition to local skin characteristics. Skin cells grow and divide without control. Hereditary factors also are at work: Psoriasis is more common in certain families and when certain genetic markers are present.

Psoriasis may be associated with depression and diminished quality of life. It’s not contagious.

About 15 percent of patients also have psoriatic arthritis, which consists of joint pain, stiffness, and swelling. It comes and goes like the skin condition and is usually mild, but it may be progressive and cause deformities. Psoriatic arthritis is most common in the fingers and toes.

Many treatments for psoriasis exist, but nothing eliminates the disease permanently. Among the treatments are the following:

Drugs that reduce T cells

Drugs that eliminate cytokines

Topical treatment with creams containing steroids

Phototherapy, exposure to ultraviolet irradiation

Immunosuppressive drugs with names like methotrexate and cyclosporine

Oral steroid drugs, like dexamethadone

Antihistamines, to reduce itching

People who have psoriasis are stuck with it for life. Most people just experience outbreaks of localized patches on the elbows and knees.

Understanding the role of vitamin D

Vitamin D has a definite role in treating psoriasis. Because the condition involves a component of adaptive immunity (the T cells; see Chapter 5), the function of vitamin D in reducing adaptive immunity plays a role. Chapter 6 discusses the ability of vitamin D to reduce cell proliferation in cancers; this action may reduce the increased production of skin cells.

Vitamin D is linked to the treatment of psoriasis in the following ways:

Exposure to the sun and the skin’s production of vitamin D decreases the severity and duration of a psoriatic outbreak.

Sunlight (heliotherapy) kills the activated T cells in the skin. Skin turnover is reduced, and the scaling and inflammation subside. Patients need only brief exposure — just minutes a day. Prolonged exposure can make the symptoms worse and damage the skin.

Various types of UVB phototherapy (broadband, narrowband excimer laser) use controlled doses of UVB light from an artificial light source. It’s used on patches of psoriasis and on psoriasis that doesn’t respond to topical treatment. The duration of treatment must be carefully monitored to avoid burns, because this is a more powerful UVB light.

UVB light therapy can be combined with topicals to make the skin more sensitive to the effect of the light.

Synthetic forms of active vitamin D, like calcipotriene or tacalcitol in topical preparations, can be used to treat mild or moderate psoriasis. It works by slowing the growth of skin cells and reducing local inflammation. Also these vitamin D drugs help make other topical treatments, like corticosteroids, more effective.

Any kind of light therapy works just like using sunlight. You must avoid excessive exposure and burning, especially in psoriasis, because excess exposure can make the disease worse. Also, taking oral vitamin D hasn’t been shown to work. The problem may be that vitamin D formed in the skin through sun exposure can lead to high levels of calcitriol that act locally to improve the psoriasis, whereas when you take vitamin D by mouth there’s no mechanism in place to tell your body to make higher levels of calcitriol just in the skin.

Linking Vitamin D Levels and Brain Health

A bunch of new information suggests that vitamin D may play a role in brain development and brain health from birth to old age. Interesting new associations link high vitamin D status to the prevention of certain psychiatric conditions and in the development of Alzheimer’s disease. This section considers the role vitamin D may play in various developmental stages and disease states, including Alzheimer’s disease, Parkinson’s disease, depression, and seasonal affective disorder.

Normal brain development

The first question researchers asked is whether there is any reason that vitamin D could be affecting the brain. They did these studies in isolated cells and in studies of animals that have brain function similar to humans. Consider some of the evidence:

Vitamin D receptors and the enzyme that converts 25-hydroxyvitamin D into calcitriol are present throughout the brain.

Calcitriol alters the expression of many genes in brain cells. This includes neurotrophins, proteins in the brain that help nerve cells survive and become more specialized.

Calcitriol helps nerve cells turn into the specialized cells that are needed throughout the brain.

The brains of animals that were born to vitamin D–deficient mothers show abnormal growth and development. Later these animals have certain behavioral abnormalities; however, these abnormalities may not be due to a direct role of vitamin D in the brain. Because vitamin D is so important for controlling how the body uses calcium, and because calcium is critical for the development of the brain, severe vitamin D deficiency in animal models may cause abnormal brain development indirectly because of calcium deficiency.

Evidence of the important role vitamin D plays in the development of the brain continues to accumulate, but more study is needed. In the meantime, here’s a look at the evidence for vitamin D in conditions that affect the brain.

Autism

The origin of autism is unknown, but the incidence of this disease has increased significantly over the last 30 years. Autism now affects 1 in every 110 children. Certain evidence suggests that vitamin D could play a role in its onset.

Reviewing autism

Autism is a mental disorder that begins in the first three years of life. It has the following characteristics:

The child doesn’t develop or is slow to develop communication skills.

The child doesn’t interact with other children.

The child performs repetitive actions, like flapping the hands or continually stacking objects.

The child doesn’t make eye contact.

The child doesn’t participate in make-believe play.

As the child gets older, he may have severe tantrums.

Up to 10 percent of individuals with autism have unusual talents, like amazing memorization ability.

These signs and symptoms continue through adulthood. Treatment consists of special education programs and behavior therapy early in life, which reduces the social and communication impairment, to some extent. Few people with autism (4 to 12 percent) ever achieve independence, and up to 50 percent need special residential care for their adult lives.

Understanding the role of vitamin D

The suggestion that vitamin D might play a role in the development of autism comes from a number of observational studies:

Autism is more common in areas with less sun. Children born in winter are much more likely to develop it than children born in summer.

Autism is more common in African-American children, whose mothers tend to have the lowest levels of vitamin D.

Animals deficient in vitamin D during gestation develop brain changes similar to those of autistic children. (Of course, they are also deficient in calcium, so this may not be a direct effect of vitamin D.)

Active vitamin D prevents the production of cytokines in the brain that have been associated with autism.

Maternal consumption of vitamin D during pregnancy has been associated with reduced symptoms of autism in the child.

This is all very interesting, but not everyone is swayed. In 2009 an editorial from the American Journal of Obstetrics & Gynecology said that the data that “support this association . . . is, at best, suggestive.” Scientists will need to establish a firmer connection before any recommendations can be considered for using vitamin D to prevent or diminish autism in children.

Alzheimer’s disease

Alzheimer’s disease is another brain disease that seems to be increasing rapidly in prevalence. It now affects more than five million Americans. Whereas diseases like strokes, heart disease, and cancer are declining, the number of people affected with Alzheimer’s disease is expanding. This fact may have to do with the aging population, but maybe there’s more to it than that. Some data even point to a possible role for vitamin D in the onset of Alzheimer’s disease. But for now, the evidence for recommending vitamin D supplementation in Alzheimer’s disease is not strong.

Explaining Alzheimer’s disease

Alzheimer’s disease (AD) is a gradual loss of mental faculties that usually begins after age 65 but can occur earlier. Most people die an average of seven years after the disease begins. Fewer than 5 percent live longer than 14 years.

Consider some of the major signs and symptoms, in the order in which they generally occur:

Loss of recent memory

Confusion

Aggression

Mood swings

Loss of language

Loss of long-term memory

Loss of control of body functions

The diagnosis is based on the progressive loss of mental function, which is confirmed by tools such as the mini-mental state examination. Sometimes MRI or CT scans of the brain are done to rule out other conditions. Observations of the caregiver are very helpful in confirming the diagnosis. Other diseases like thyroid disease, liver disease, and diabetes can be ruled out with blood tests.

As the disease progresses, the patient goes from being independent to being completely dependent upon caregivers. Memory deteriorates to the point that the person may be living in the past, not recognizing children and spouse any longer. The patient is apathetic and can’t feed or care for himself. Often Alzheimer’s patients eventually die of an infection like pneumonia or from infected bed sores.

The cause of Alzheimer’s disease is not known. Treatment consists of drugs to improve brain function, but these drugs don’t help much and don’t slow the progression of the disease. Psychological treatments such as trying to identify the causes of difficult behavior and then avoid them, or helping the patient remember the past by discussing it or showing pictures haven’t been too helpful, either.

Understanding the role of vitamin D

Some studies (but not all) have shown elderly people with poor memory recall are likely to have low serum levels of vitamin D. In addition, the lower the serum 25-hydroxyvitamin D level, the more difficulty people have with memory and judgment.

Alzheimer’s patients show this relationship as well. Some of the evidence that Alzheimer’s disease may be a vitamin D deficiency disease, at least in part, includes the following:

Alzheimer’s disease is found much more often in temperate than in tropical climates.

Patients with AD have lower levels of vitamin D in their blood than the normal population.

Among patients with Alzheimer’s disease, those with higher levels of vitamin D perform better on tests of knowledge.

It may be, however, that low serum 25-hydroxyvitamin D levels are a reflection of the poor health, diet, and lack of outdoor physical activity of people with dementia and not that lack of vitamin D leads to dementia. That’s not a subtle point — if the low vitamin D status comes after the disease, then giving more vitamin D won’t have any impact on their neurological disease.

Some other findings suggest the effect of vitamin D might be direct:

In cell culture studies, calcitriol has the ability to increase the uptake of amyloid by immune cells called macrophages. Amyloid is a product found in the brain of people with AD that’s thought to contribute to the disease process. If this effect of calcitriol on macrophages could be shown in people, vitamin D could slow the progression of AD.

Elderly patients who have low serum levels of vitamin D (less than 10 ng/ml or 25 nmol/L of 25-hydroxyvitamin D) are 60 percent more likely to develop dementia over the next six years than those with a high level (greater than 30 ng/ml or 75 nmol/L).

Again, researchers have interesting associations but no absolute proof that vitamin D insufficiency is related to higher rates of Alzheimer’s disease. They’ll need to do some controlled research to see if avoiding vitamin D deficiency prevents AD or if giving vitamin D to people with AD reduces their disease symptoms.

Parkinson’s disease

Parkinson’s disease (PD) is another brain disease, but this one affects motor skills instead of learning, knowledge, and memory. Currently, about one million people in the United States are believed to have Parkinson’s disease, but an additional three to four million people don’t know they have it.

The connection between Parkinson’s disease and vitamin D is about as strong as the link between vitamin D and Alzheimer’s disease. Researchers have found some promising associations.

Explaining Parkinson’s disease

Parkinson’s disease begins over the age of 50. The condition is believed to result from the loss of dopamine-producing brain cells. Dopamine is a brain chemical that is essential to the transmission of impulses from one nerve to another.

Consider the major symptoms of Parkinson’s disease:

Trembling of the hands, arms, legs, jaw, and face. The tremor occurs when the patient is at rest and disappears when the limb moves.

Stiffness of the arms, legs, and trunk. The patient may feel pain in the joints; when they’re moved, they have a stop/go feel to them.

Slowness of movement. The patient shuffles along and has difficulty executing any complex movement.

Impaired balance and coordination. The patient tends to fall, especially in the late stages of the disease.

These signs and symptoms are the major ones, but patients show all kinds of movement disturbances, including a bent posture, small steps, trouble with speech and swallowing, and small handwriting.

Patients also have problems with knowledge and memory, although not as severely as in Alzheimer’s disease at the beginning. Symptoms can progress to severe loss of memory and thinking ability, however.

Many causes have been suggested for Parkinson’s disease. The causes that have the best evidence behind them are listed here:

Genetic: Mutations of genes have caused PD.

Toxins: Some pesticides have been associated with PD. Mercury poisoning has also been suggested.

Head trauma: Many PD patients have a history of head trauma.

PD is diagnosed by observing the four major signs described previously. No blood test signifies PD, and X-rays aren’t helpful except to rule out other diagnoses.

Several drugs can help reduce the signs and symptoms, but nothing is curative. If drug therapy is inadequate, surgery can be performed either to produce lesions in certain parts of the brain or to do deep brain stimulation to send impulses into the brain.

Understanding the role of vitamin D

The best evidence linking vitamin D to PD comes from a study published in the July 2010 issue of the Archives of Neurology. The study took place in Finland, which has little sunlight exposure and whose population has low serum levels of 25-hydroxyvitamin D.

Researchers followed more than 3,000 people for 29 years beginning at age 50. None had Parkinson’s at the beginning of the study. During the duration of the study, 50 cases of PD developed. When the researchers measured serum 25-hydroxyvitamin D levels from blood collected at the beginning of the study, they found that if the vitamin D level had been at least 20 ng/ml or 50 nmol/L (adequate) at the beginning of the study, the incidence of PD was 65 percent lower than if it had been 10 ng/ml or 25 nmol/L (deficient).

Experts don’t understand just how vitamin D might play a role in PD. Some of the suggested explanations include the following. Vitamin D

Protects nerves by preventing oxidation that kills nerve cells.

Decreases immune damage to nerve tissue.

Improves nerve conduction.

Decreases damage to nerve cells that produce dopamine by toxins.

Still more information connects PD to vitamin D deficiency. Some of it includes these points:

Calcitriol can prevent experimental PD in animals.

Parkinson’s disease is much more common in higher latitudes than in the tropics.

Unfortunately, there is also a lot of conflicting data related to vitamin D and PD that make it hard to fully embrace the relationship. Still, based on the Finnish study, the evidence shows that it may be important to keep your serum 25-hydroxyvitamin D levels higher than 20 ng/ml or 50 nmol/L — the same amount recommended to protect bone health. The PD relationship is just another good reason to keep your vitamin D status above this level.

Depression

If vitamin D may play a role in several brain disorders that cause depression, is it any surprise that people have looked for a role for vitamin D in depression?

Depression, which psychiatrists officially call major depressive disorder, is a mood disorder that varies greatly in its prevalence and severity. Using a broad definition of depression, about 4 percent of men and 8 percent of women will have depression over the course of a year.

Reviewing depression

Depression can occur at any age, but the incidence of this condition begins to increase around age 30. If you’re diagnosed with depression, it means you have five or more of the following symptoms, the first two of which must be present; you also must have the symptoms for at least two weeks:

Decreased interest in most or all activities most of the day, every day

Depressed mood most of the day, every day

Feelings of worthlessness every day

Insomnia or increased need to sleep every day

Loss of energy every day

Restlessness or slowed behavior every day

Significant weight loss or weight gain, or decrease or increase in appetite

Thoughts of death or suicide, or a suicide attempt

Trouble making decisions and concentrating every day

Depression has many causes, including chemical-biological abnormalities in the body, psychological abnormalities, and social factors:

Certain genes may determine whether you respond to life events with depression.

You may have a lack of the chemicals in your brain that lift mood.

Structural abnormalities in the brain can be a cause.

The biological clock may be abnormal, with problems sleeping and staying awake.

Negative psychological responses to life events play a role.

Low socioeconomic status coupled with feelings of hopelessness to change may be important.

Substance abuse such as alcoholism or drug abuse may precede major depression.

Just as depression has many different potential causes, many different treatments are used, from antidepressant drugs to talk therapy or a combination of both. Electroconvulsive therapy, formerly known as shock treatment, has regained some of its favor as a useful treatment for severe depression. Physical exercise can also be helpful if the patient can be induced to exercise.

The prognosis for depression isn’t good. About 3 to 4 percent of patients (many more men than women) commit suicide or die early from some other cause, like heart disease. Most patients have an average of four episodes of major depression during their lives. However, even without any treatment, about 20 percent of patients recover. Each episode of depression lasts a little less than six months.

Understanding the role of vitamin D

It seems fairly clear that if a lack of vitamin D is associated with other diseases that have depression as a central feature, like Alzheimer’s disease and Parkinson’s disease; the same should be true for depression itself. Some evidence for a link between vitamin D and depression includes the following:

Several studies show an association between low serum 25-hydroxyvitamin D levels and depression. For example, women and men with levels of vitamin D below 20 ng/ml or 50 nmol/L were more likely to have depression than those with higher levels. People with serum 25-hydroxyvitamin D levels less that 20 ng/ml or 50 nmol/L were also more likely to develop depression over a six-year follow-up.

Similarly, in a clinical trial of 441 obese and overweight Norwegian people, those with serum 25-hydroxyvitamin D levels less than 16 ng/ml (40 nmol/L) were more likely to be depressed. When these people were then given either a placebo or two high-dose vitamin D interventions (20,000 or 40,000 IU per week), after a year the number of people with depression was lower in the vitamin D groups.

Although not all association studies show a link between serum 25-hydroxyvitamin D and depression, this last study shows how promising the link is. For now, it makes sense to keep your serum 25-hydroxyvitamin D levels over 20 ng/ml (50 nmol/L).

Seasonal affective disorder

Seasonal affective disorder (SAD) is a form of depression that occurs during long months without sun, usually in the winter. This condition is also called winter depression or the winter blues. The signs and symptoms are similar to those of major depression, but they subside when the warm spring replaces the harsh winter. SAD occurs especially at the highest latitudes, such as in Finland and the other Nordic countries, where as many as 10 percent of the population suffers from the condition. Remember, winter and high latitudes are the conditions that also result in low serum levels of 25-hydroxyvitamin D. The question is whether low vitamin D status is a direct cause of SAD, or if they’re two things that just happen to be independently affected by season.

Reviewing seasonal affective disorder

The signs and symptoms usually include the following:

Depression

Excessive intake of carbohydrates, with weight gain

Excessive sleep, with trouble waking up

Little energy

Morning sickness

Occasionally SAD can also occur in the summer. When this happens, it may be the result of too much time spent indoors.

The cause for SAD is thought to be a lack of a neurotransmitter, serotonin. Drugs that increase brain serotonin decrease the disorder. Some think that SAD may be a result of our evolution as a species; some of our mammal ancestors hibernated in the winter, and SAD may be a response to our body’s inability to hibernate.

Light therapy and the coming of spring are excellent forms of treatment for SAD. The patient is exposed to bright light for 30 to 60 minutes daily for several weeks.

Understanding the role of vitamin D

Except for the fact that both low serum 25-hydroxyvitamin D levels and SAD are both prevalent in winter, there’s not a whole lot of evidence to link the two. Some of the best include the following.

On the positive side, a small study of just eight people with SAD found that a dose of 10,000 IU vitamin D improved depression within a week; however, in 2006, a much larger study of 2,000 healthy, older women in England showed that 800 IU of vitamin D daily for six months didn’t affect the development of SAD.

Still, it’s well known that exposure to light reduces sleepiness and depression in patients with SAD; however, light stimulates a part of the brain called the pineal gland and leads to more production of serotonin that then becomes melatonin. These chemicals are known to improve mood and sleep-wake cycles. It’s because of this that many scientists think in this case, low serum 25-hydroxyvitamin D is just a marker for low sunlight exposure and, therefore, low production of serotonin and melatonin.

Most experts agree that taking vitamin D in the winter is a good idea because skin synthesis is lost during these months. The added bonus that it may help prevent SAD is even more reason to follow their advice.

Managing Your Weight

In our increasingly overweight society, weight management has become important. Substantial information suggests that vitamin D plays a role in fat cell biology and that this may relate to weight loss and weight management.

Fat ties up vitamin D. If an overweight person and a normal-weight person take the same amount of vitamin D, the blood level of vitamin D in the normal-weight person goes higher than in the overweight person. The only way an overweight person can get that vitamin D back is by losing weight.

Several observations are consistent with the idea that vitamin D, as well as calcium, may be important in weight loss or weight maintenance. Unfortunately there are inconsistencies between the studies, and often vitamin D and calcium are given together, which makes it impossible to separate their effects on fat. Among them are the following:

Higher calcium intake is associated with lower body weight in people and animals. This lowers the serum level of active vitamin D (calcitriol), which suggests that calcitriol normally promotes fat gain.

Fat cells have the enzyme that allows them to make calcitriol from 25-hydroxyvitamin D. This suggests fat cells may be influenced by calcitriol even when the serum level of calcitriol doesn’t change.

Blood levels of parathyroid hormone, which rise when vitamin D status falls, are associated with more obesity; however, when this happens, serum calcium can also fall.

Contrary to the idea that high calcium suppresses obesity by reducing calcitriol levels, calcitriol suppresses the formation of mature fat cells in cell culture experiments.

Confounding the picture somewhat, the vitamin D receptor independently promotes the formation of fat cells. This is why mice lacking the vitamin D receptor have less body fat than normal mice.

Increasing vitamin D status from serum 25-hydroxyvitamin D levels of 15 to 30 ng/ml (37.5 to 75 nmol/L) was associated with more effective weight loss in a controlled two-year program.

All of this is very interesting and shows that calcitriol plays a role in how a fat cell works. We still don’t know, however, if there is a reliable benefit to either maintaining weight or losing weight that comes from taking more vitamin D. We have to wait for more research to get that answer.

If you’re planning weight-loss surgery (bariatric surgery), one of the complications is poor absorption of vitamin D and other fat-soluble vitamins. Post-surgical patients must take vitamin supplements to maintain target levels of vitamin D and other nutrients. You want to be sure that your vitamin D blood level is normal so that if the association showing that high vitamin D status helps with weight loss turns out to be true, your weight loss proceeds at a satisfactory rate.

Looking at Fibromyalgia

Fibromyalgia is a chronic condition associated with pain in the muscles and bones, as well as any of the following signs and symptoms:

Fatigue

Joint stiffness

Lack of abnormal diagnostic tests

Lack of abnormalities on physical examination

Sleep disturbance

The lack of abnormalities results in confusion over whether this is a disease or a psychiatric condition. Many theories abound, but no cause has been found. Patients are often depressed because of the inability to live a normal life and the failure of treatment. Some of the features of the condition are consistent with the response to chronic stress.

Treating fibromyalgia is difficult and focuses on the symptoms that are occurring. If pain is prominent, pain medication is offered. If the patient is depressed, antidepressants are given. Psychotherapy also may help.

When vitamin D levels are measured in patients with fibromyalgia, as many as 60 percent have low levels of 25-hydroxyvitamin D. Whether this means low vitamin D causes fibromyalgia is unclear; it may instead be the result of fibromyalgia patients not getting outdoors or consuming a healthy diet due to pain, stiffness, and depressed mood. If patients are treated with vitamin D, many, but not all, gradually get better over a prolonged period of time. Sometimes it takes several months for the patient to feel better. Also promising are the results from a recent study of 100 older people with serum 25-hydroxyvitamin D levels below 25 ng/ml (62.5 nmol/L) that showed people with lower levels were more likely to have fibromyalgia, and that those who got 50,000 IU vitamin D per week for eight weeks reported lower scores on clinical tests designed to identify the signs and symptoms of fibromyalgia.

Still, with such a mysterious disease, much more investigation is necessary before the role of vitamin D in fibromyalgia, if there is one, is established.