Vitamin D Blood Tests May Be Unreliable--Particularly In Overweight People

As the Vitamin D debate rages on, it seems that practically every day a new related study emerges.

Vitamin D, the reigning health topic du jour, has been linked to cancer, diabetes, obesity, the autism spectrum, unhealthy aging, and a myriad of other health issues--basically everything. (the more illnesses it is linked to, the more pills marketers can sell).

There are many dubious pundits claiming that there is an epidemic of vitamin D deficiency, with some proclaiming that as many as 75% of all people are deficient, and therefore, everyone should be supplementing with Vitamin D tablets, particularly those who get little sun exposure and the elderly.

I don't agree with the statistics regarding the number of people with deficiency because I think the blood tests don't tell the whole story, and a recent study involving obese and non-obese people makes me think I am right. Notice the emphasis on think, not know. (By the way, another recent study revealed that two out of three of the main pieces of equipment used by blood labs to measure Vitamin D often report artificially low numbers.)

Before I get to the main study, here's what everybody seems to agree on in regards to Vitamin D:

1. Vitamin D is a group of fat soluble substance most call a vitamin. (There is some disagreement if it's really a vitamin as the body can produce it on its own, unlike all other vitamins which must be derived from external sources. However, Vitamin D is often called the "sunshine vitamin" because the body can produce it from cholesterol after your skin is exposed to sun.)

2. Human beings can consume two forms of Vitamin D: cholecalciferol (vitamin D₃) or ergocalciferol (vitamin D₂). The liver apparently converts Vitamin D to calcidiol and the kidney converts some of it to the active form called calcitriol. Blood tests measure only calcidiol.

3. Vitamin D deficiency can cause osteomalacia (rickets in children), a disease related to softening of the bones due to problems with bone mineralization.

4. There is more vitamin D stored in fat or adipose tissue than typically circulates in the blood. That makes sense because it is fat-soluble. (There is some disagreement if they are positively or negatively correlated, eg. whether they increase and decrease together.) What is known for sure is that generally the more fat you have, the more Vitamin D is stored in such fat.

5. Routine Vitamin D blood tests only measure circulating Vitamin D (calcidiol) and not fat stored Vitamin D. (There are ways, such as liquid chromatography, to measure fat-stored vitamin D, but they are not part of normal testing.)

6. Obese people have lower levels of circulating and higher levels of fat-stored Vitamin D than non-obese people.  Basically, the more fat you have, the more of your Vitamin D is stored in it and the less you have circulating and easily measurable. (This could explain why some scientists claim there is more Vitamin D deficiency today than ever before. It could be a result of an increasing weight among Americans with 2 out of 3 now deemed overweight and 36% purported to be obese.)

7. Vitamin D blood levels increase with weight loss. (It is not clear what happens to the total amount of fat-stored Vitamin D with weight loss, but presumably it decreases.)

8. Wild fish such as salmon are still a great source of Vitamin D.


Here are the questions whose answers have less agreement, if not outright disagreement.

1. What levels of blood circulating Vitamin D define deficiency and inadequacy?

2. Can the body tap into fat-stored Vitamin D when needed?

3. Why do vitamin D blood levels increase with weight loss?

4. Why do obese people have lower levels of circulating blood Vitamin D?

5. When and how much supplementation is necessary and appropriate for different levels of deficiency or inadequacy.

6. In the absence of deficiency or inadequacy, does extra Vitamin D offer any special protection against cancer, diabetes, heart disease, diabetes, etc.?

The recent study about Vitamin D, I referenced above, showed that in comparing obese young men to normal weight young men, the obese young men when exposed to tanning radiation akin to sun exposure actually seemed to produce 57% less Vitamin D than the non-overweight young men exposed to the same radiation. The results suggest that the obese get less Vitamin D from sun exposure that the non-obese. 

The authors of the study contend that the reason for this result is that the fat or adipose tissue in the obese men may absorb the additional Vitamin D produced.  The authors also put forth the supposition that obese people have less Vitamin D to start with because they spend less time in the sun.

This study triggered an exhaustive research effort by me to better understand the science of how vitamin D moves in and out of fat storage. More specifically, I wondered if one has a high level of Vitamin D in fat storage and a low level in blood circulation, would the Vitamin D come out of storage before a clinically evident deficiency develops. In other words, can you depend on your fat-stored Vitamin D to play a helpful role and prevent deficiency? If your fat-stored vitamin D provides the body with necessary Vitamin D, then we can dispense with all the blood tests for circulating Vitamin D because they would be unreliable indicators of deficiency and inadequacy.

The study, among others, seemed to suggest that the more obese you are, the more of your Vitamin D would go into fat storage and therefore there would be less in blood circulation. This means that the more obese you are, the more Vitamin D deficient you would be on blood measurement. If this would be a true deficency, one would expect to see cases of osteomalcia among the morbidly obese.

Guess what? After reviewing every published study available on pubmed, it was startling that there was not a single case or study reported that demonstrated bone related problems with rising obesity. In fact, it doesn't even seem to lead to osteoporosis, another bone related disease, and in fact, scientists have long believed that obesity protects against osteoporosis.  (Some recent studies out of China that differentiate between obesity based on body mass index versus actual body fat composition suggest that obesity based on high fat composition may not be preventive of osteoporosis.)

Furthermore, the only studies linking osteomalacia to obesity involve obese patients who undergo a surgical procedure to lose weight called the jejunal-ileal bypass. This procedure can sometimes lead to malabsorption, a condition in which the body can't absorb certain nutrients, in which case all kinds of problems and deficiencies become more likely.

This knowledge raises a serious question regarding the validity of the widely used Vitamin D blood test. If the test does not correlate to clinical symptoms, of what value is the test?  When the test shows a low level, is it because it is actually absent throughout the body or because much of it is stored in the fat, thereby undetectable by the blood test?

Although the study postulated, and other studies have also shown, that Vitamin D levels increase with weight loss, allegedly due to more outside exercise and therefore more sun exposure, I offer an alternative theory.  I say theory because I can't support what I suspect is the case because I couldn't find a single study that has considered this issue. Like all theories, it needs to be tested.

I postulate that as body fat shrinks, stored Vitamin D is released into circulation. What I don't know if having more blood circulating versus fat-stored Vitamin D actually makes a health difference? The answer to this question is imperative to know definitively before we compel so many people, particularly the overweight and obese to unnecessarily supplement with Vitamin D for the sole purpose of increasing circulating levels of Vitamin D.

Until the role of fat-stored Vitamin D is elucidated, I think most of the rest of the studies on Vitamin D will be essentially meaningless because you aren't measuring all the Vitamin D in the body.

For example, another study showed that there is an increased incidence of developing metabolic syndrome and a larger waist circumference after five years in patients with low blood Vitamin D.

My questions, which this study did not fully answer, are did they really have low total body Vitamin D or was it low in the blood because most of it was stored in fat. Also, did the low Vitamin D levels put them at greater risk because they were already overweight and/or pre-diabetic or because they had low sun exposure and poor dietary intake?  Finally, does low Vitamin D cause problems or indicate they already exist?

Perhaps it is not the Vitamin D blood level that matters but the presence of excess fat? Perhaps it is the excess Vitamin D that is stored in the fat that is causing the problems? We must know more about the role and activity of the fat-stored Vitamin D to answer these questions.

Maybe Vitamin D is a proxy for something else. It won't be the first time in medicine that we discovered that something was not what we thought it was. For example, we thought ulcers were caused by stress and it turned out to be mostly bacteria infections. We thought homocysteine controlled heart disease and it turned out to be only a bio-marker. We thought taking beta-carotene would prevent cancer, but it turned out that to be just the opposite. We thought statins were great for us...wait, many, but fewer still think that but maybe that will change some day as well.

From my perspective, I will no longer be recommending, in the absence of symptoms, Vitamin D supplementation for levels above 25 in overweight and obese patients. I will however, continue to strongly recommend (and offer extensive support to) overweight people to help them lose weight, not only for the sake of increasing their Vitamin D levels, but also for all the other health benefits such weight loss confers.

Also, for those without history of skin cancer, I continue to advocate for at least 15 minutes per day of sun exposure to extremities or belly, as long as reddening of the skin is avoided. Based on my current knowledge, this appears to beat supplementation almost every time, even in the elderly.

Vitamin D is obviously a complicated issue that begs for real clarity. Major studies are underway which may offer some real answers.  However, if they don't consider the role of fat-stored Vitamin D, they may actually be of little value. Let's hope for the some good answers and in the interim, try to stay healthy the old fashioned way- get up, get out, and move around.  Of course, watch what you eat because it is still the single most important determinant of health.

A Vitamin D Study Worth Ignoring and Good News at MDPrevent

It seems like everyone wants in on the Vitamin D hoopla. A study published in Mongolia (not sure if it's Outer Mongolia-the place many often refer to as a wasteland) shows that children who increase their Vitamin D levels suffer fewer cold symptoms. The only problem is that it only works with children who are Vitamin D deficient due to lack of sun during their winter (maybe it is Outer Mongolia).

There is no one, including me, that will argue that the body needs Vitamin D and without an ample supply your body will not function properly. And by not function, that includes an immune system incapable of warding off even the simple and ubiquitous cold virus. But the real debate is what defines a clinical relevant deficiency and what's the best way to treat it. I vote sun, wild Salmon, and almond milk in that order over supplements. Nevertheless, while the question of deficiency still begs an answer, with all the studies now underway, I hope the question won't stay unanswered for long. For the moment, I encourage patients to consciously raise their levels if it is below 30.

On another note, it's turned out to be an unexpectedly busy summer. Without warning, MDPrevent is suddenly inundated with patients wanting access to our medical care, particularly our weight loss and diabetes education services. Word of mouth has generated excitement about our drug-free, fully paid for by Medicare approach to successful weight loss. Even doctors such as cardiologists and endocrinologists we've never met are now referring patients to us because they are witnessing first-hand the weight loss success their other patients are enjoying.  It's both exhilarating and exhausting at the same time. It's actually getting tough to schedule new patients.

Why is it working? What have we discovered that seems to elude others? The answer is simple. Teamwork. Our program combines the skills of a physician, a registered dietitian, and a clinical psychologist. Each of us works in unison to guide, encourage, and cheer each patient on. The result is that patients are steadily losing weight, lowering cholesterol, and starting to enjoy their former selves again.

For those of you who have referred friends, relatives, and neighbors, we say thank you. I suspect so do the people you referred.

Finally, someone asked me the other day if I enjoy what I do. I said of course because what can be more gratifying than seeing people turn their lives around and feel in control again for the first time in many years!  It really does feel good to do good!

I hope you all have a wonderful and relaxing Labor Day weekend.
 

IMPORTANT ALERT: Blood Pressure Medication and Lip Cancer

This is a special alert for patients taking blood pressure medications such as hydrochlorothiazide (a diuretic) and Nifedipine (calcium channel blockers).  According to a new observational study, both of these drug classes appear to increase a patient's hypersensitivity to sunlight. The study shows a link between these medications and the development of squamous cell skin cancer of the lips. It is believed that the combination of increased sun sensitivity and sun exposure is the culprit.

DO NOT stop taking these medications without the advice of a doctor. However, if you are on these medications, please limit your sun exposure. If you limit your sun exposure, you will unfortunately increase your risk of a Vitamin D deficiency. Therefore, please make sure to get more Vitamin D in your diet from sea kelp, sea vegetables, wild salmon, and vitamin D fortified foods.

Dr. Oz's Vitamin D Recommendation Doesn't Hold Up To USPSTF Review

Yesterday, a patient came to see me again because she was concerned that I had recommended that she stop supplementing with Vitamin D. I had previously told her that she should get her Vitamin D (and fish oil) naturally from eating Wild Alaskan Salmon and other fish rich in Omega-3 fatty acids such as halibut, cod, sardines, anchovies, herring, etc. at least three times a week, and from fortified foods such as unsweetened almond milk.

She had just been to another doctor for the thyroid disorder I had diagnosed who suggested she reinstate her taking Vitamin D. She wasn't happy in general with this particular endocrinologist, but wanted to discuss what to do next with her thyroid disease and his advice about Vitamin D.

I explained again that my recommendation was based on the prevailing science and the fact that she had a very good level of Vitamin D based on her bloodwork.

As fate would have it, in a draft recommendation released yesterday, the United States Preventive Task Force (USPSTF), confirming my recommendation, said there is no value for postmenopausal women in taking supplements up to 400 IU of vitamin D and 1,000 mg of calcium.

The USPSTF also found the evidence too scant to draw conclusions about vitamin D supplements, at any dose and with or without calcium, for cancer prevention in adults.

It was based on an evidence review finding that "in postmenopausal women, there is adequate evidence that daily supplementation with 400 IU of vitamin D3 combined with 1,000 mg of calcium carbonate has no effect on the incidence of osteoporotic fractures. However, there is inadequate evidence regarding the effect of higher doses of combined vitamin D and calcium supplementation on fracture incidence in postmenopausal women."

At the same time, the USPSTF found, doses at or below 400 IU of vitamin D and 1,000 mg of calcium increase the risk of kidney stones, albeit to a small degree.

But with no benefit from the supplements, even the small risk of harm is enough to tip the balance against them at these low doses, the group indicated.

The bottom line is there are no clear benefits of taking Vitamin D and calcium supplements and you can get all the Vitamin D your body needs, in the absence of deficiency, from natural sources including sun exposure, Wild Salmon, other fishes, etc.

Nevertheless, Dr. Oz repeatedly recommends Vitamin D as a top anti-aging supplement.

What are you going to follow: Science or marketing?

MDPrevent

Another Reason To Go Wild Over Wild Salmon

Too many doctors have bought into the hyperbole regarding vitamins and other dietary supplements, often recommending them without all the facts. Some even go so far as to sell them without regard to consequences. Don't even get me started again about Dr. Oz.

For example, there has been such a preponderance of media coverage about Vitamin D deficiencies that you would think that everyone has a Vitamin D deficiency. It's simply not true. We often search without success.

Nevertheless, by now, unless you have been living in a cave, you've most likely heard the Vitamin D Story. If not, it goes like this. We need Vitamin D and we can get from 15 minutes a day of sun exposure. However, because some people don't get much some exposure for good parts of the year based on their geographic location, or because of they are afraid of sun exposure due to skin cancer, or because as people age they produce less Vitamin D from sun exposure, we need to supplement with Vitamin D.

Although products like Almond milk and regular milk are fortified with Vitamin D, as are a number of other processed foods like cereals, many still recommend supplementation in case we are not getting enough.  I do not recommend supplementation in the absence of known deficiency and because there is a viable alternative.

There is a great source of Vitamin D that also offers other potent nutrients and that is Wild Salmon. I sing the praise of Wild Salmon so much you'd think I owned a fish company. Well, I don't. But I am a huge fan because of the medicinal benefits of Wild Salmon. First, the wild variety has 4 times the Vitamin D than the farm raised variety. A 3.5 ounce Wild Salmon steak also has over 200% of the recommended daily allowance of Vitamin D.  In addition, Wild Salmon also has the omega-3s (EPA and DPH) which have cholesterol lowering, anti-inflammatory, and apparent pro-brain health effects. Finally, Wild Salmon is a great source of protein for your diet.

Cod liver oil is another great source of Vitamin D, but it has its own set of issues so I recommend Wild Salmon any day over it. In fact, consuming Wild Salmon 3 to 4 times a week would be wise.

So isn't it time you got rid of your Vitamin D pills and consumed a natural source of it?

What's The Big Deal About Vitamin D? It turns out quite a bit.

Vitamin D deficiency has become a hot topic with headlines about its dangers becoming ubiquitous.  Of course, not everyone agrees on what the problem is and how to best treat it.  

Accordingly, I’ve compiled a list of questions and answers to help people navigate through the plethora of issues raised. If you have additional questions, please send me an email at steven.charlap.md@mdprevent.net.

1.      Can sun exposure restore vitamin D to adequate levels?

It is well documented that lack of exposure to sunlight is a major risk factor for vitamin D deficiency. Therefore, you would think if you increased your exposure to sun, you would be all set. That may not be the case according to one doctor.

Here is an excerpt from Medscape News article from today:

"The 'epidemic' in vitamin D deficiency is clearly not from too little sun exposure," and dermatologists can be confident in insisting that their patients continue their sun protection efforts, said Richard Gallo, MD, PhD, here at the American Academy of Dermatology (AAD) 70th Annual Meeting.

"Clearly solar exposure is an influence — there is no doubt about that — but you cannot predictably say that a certain amount of exposure will normalize vitamin D deficiency," said Dr. Gallo, chief of dermatology and professor of medicine and pediatrics at the University of California, San Diego.

I’m not sure that all doctors agree with Dr. Gallo and I still believe that some sun exposure, up to 15 minutes per day (avoid mid-day peak sun) is prudent unless you have already had skin cancer. By the way, your belly skin absorbs sun the best.

2.      What level of Vitamin D defines deficiency?

Serum 25(OH)D - The circulating half-life of 25(OH)D is 2 weeks. This is the best test to determine vitamin D status. A 25(OH)D level of less than 32 ng/mL is considered vitamin D insufficient. A 25(OH)D level of less than 15 or 20 ng/mL have been used to define vitamin D deficiency. Intestinal calcium absorption is optimized at levels above 32 ng/mL. An Institute of Medicine report recommends that patients should have serum vitamin D levels above 20 ng/mL, but the American Endocrine Society sets this level at 30 ng/mL

One issue I have not seen addressed is the fact that Vitamin D is a fat soluble vitamin and blood teats only detect circulating Vitamin D and not fat-stored Vitamin D. I'm not sure if this is significant in diagnosing deficiency, but I would love to hear if you know of anyone who studied this issue.

3.      Who should be tested for Vitamin D deficiency

It is generally recommended to screen only those individuals who are at high risk for vitamin D deficiency, including patients with osteoporosis, malabsorption syndromes, black and hispanic individuals, obese individuals (BMI >30 kg/m²), and those with several other medical conditions.

I don’t agree with these recommendations as I have found deficiency among a much broader group of patients. I don’t believe we should test everyone, but I do believe in testing everyone over the age of 65 who routinely avoids sun exposure.

4.      Is testing of parathyroid hormone (PTH) necessary to make the diagnosis of Vitamin D deficiency?

No, but it is helpful. An elevated PTH is supportive of the diagnosis.

5.      What is the recommended daily intake of Vitamin D?

There is some debate on this one. Some say for adults it is 800 IU, others 1,000 IU, and still others, even higher. I unscientifically vote for 1,000 in absence of deficiency and initial 2000 to restore levels. Others supplement at much higher dosages, even to 50,000 IUs. 

6.      Is Vitamin D toxic at higher levels?

At blood levels of 125 ng/ML, Vitamin D may be toxic and that is why I believe in treating deficiency more cautiously so to avoid going from one unhealthy extreme to another. Doses can always be increased as needed. Obviously, the greater the deficiency, the higher the restorative dose should be.

7.      Which form of Vitamin D--D2 or D3--is best to treat deficiency?

Most scientists agree that D3 (cholecalciferol) is much better but studies support D2 (ergocalciferol) as well. Stick with D3 which everyone accepts.

8.      Is milk a good source of Vitamin D?

Milk may be an unreliable source.  Fortified milk may contain less than the stated amount of vitamin D3 on the product (in some cases less than 80% of the amount), so if the only reason you are drinking milk is for Vitamin D, drink Almond Milk instead which is also fortified.

9.      What foods are good sources of Vitamin D?

Most dietary sources of vitamin D do not contain sufficient amounts of vitamin D to satisfy daily requirements. Foods thought to contain high amounts of vitamin D3 are oily fish, such as salmon and mackerel. A single serving (3.5 oz) of wild-caught salmon has 988 ± 524 IU vitamin D3, an amount that remains unchanged after baking but that decreases by 50% if the salmon is fried in vegetable oil. In comparison, farm-raised salmon has only 25% the content of vitamin D3 found in the flesh of wild salmon, whereas blue fish and mackerel have even lower vitamin D3 levels, at 280 ± 68 and 24 IU, respectively. Vegetables and fruits are not a good source for vitamin D.

The following foods contain the indicated amounts of vitamin D, as reported by the US Department of Agriculture's (USDA's) Nutrient Data Laboratory

·         Fortified milk (8 oz) - 100 IU

·         Fortified orange juice (8 oz)  100 IU

·         Fortified cereal (1 serving) - 40-80 IU

·         Pickled herring (100 g) - 680 IU

·         Canned salmon with bones (100 g) - 624 IU

·         Mackerel (100 g) - 360 IU

·         Canned sardines (100 g) - 272 IU

·         Codfish (100 g) - 44 IU

·         Swiss cheese (100 g) - 44 IU

·         Raw shiitake mushrooms (100 g) - 76 IU

·         Most multivitamins (1 tab) - 400 IU

10.  Does Vitamin D deficiency lead to cancer, both types of diabetes, and increased mortality (death)?

Recent studies suggest that it does, but further study is necessary. Best to stay at healthy blood level regardless of future study results.

11.  Are there prescription drugs that lead to Vitamin D deficiency?

Drugs such as Dilantin, phenobarbital, and rifampin can induce hepatic p450 enzymes to accelerate the catabolism of vitamin D.

12.  Does Celiac Sprue increase risk for Vitamin D deficiency?

Yes, due to malabsorption.

13.  Who is at greatest risk of Vitamin D deficiency?

Elderly homebound and institutionalized individuals don’t get much sun exposure. However, a study from Boston determined that nearly two thirds of healthy, young adults in Boston were vitamin D insufficient at the end of winter. People with dark skin and older people are also at increased risk because their skin does not absorb sunlight as well as others.

14.  Are there any physical findings for Vitamin D deficiency?

Other than rickets and osteoporosis in extreme cases, in adults with a severe vitamin D deficiency, a physical examination can reveal periosteal (outer surface of bone) bone pain. This is best detected using firm pressure on the sternal (chest) bone or tibia (larger leg bone).