Skip to comments.Vitamin D levels tied to colon cancer risk
Posted on 09/02/2011 6:19:15 AM PDT by decimon
NEW YORK (Reuters Health) - A new analysis of earlier research finds that both higher vitamin D intake and higher blood levels of the vitamin's active form are linked to lower risk of colon and rectal cancers.
In 18 studies that included more than 10,000 people, colon cancer risk was as much as 33 percent lower in subjects with the highest blood levels of vitamin D compared to those with the lowest levels, researchers report in the Journal of Clinical Oncology. Those with the highest intake of vitamin D through supplements and food had 12 percent lower risk than those with the lowest intakes.
Limitations of the analysis, the researchers note, included the lack of uniform criteria for comparison groups across the various studies; also, not all of the studies had information on vitamin D intake or its blood levels for individuals, only ranges for groups. The "lowest" and "highest" categories in different studies also varied significantly.
(Excerpt) Read more at news.yahoo.com ...
I take mine every morning.
When i was younger I drank milk like crazuy and felt great
Stopped and felt terrible
gone back to drinking it all the time and feel much much better
I could live on milk and bananas and orange juice.
Another slam for the “get out of the sun” alarmists—
This summer, I started the 15-30 minutes in the sun thing and feel a lot better. The trick is to not wash it off.
As you pointed out, it only takes 15 minutes, unless....
unless you live north of say, the Gulf Coast, durign the Winter. At that point, as I understand it, the UV level of the sun is not high enough for the body to producte vitamin D. The best solution during those months is to eat high vitamin D foods (fish, cod liver oil, eggs) or take a quality supplement.
Over here, I try to make sure my family eats fish about twice a week during Dec, Jan and Feb. (Lot’s of good choices, one of my favorites is grilled salmon—easy to do, wrap salmon along with spices, bit of butter, onion, pepper, whatever you like, in foil and place on a grill for 20 minutes.)
Correct the misleading headline. It is not “tied to”. It actually lowers the colon cancer risk.
Most silver citizens require vitamin D supplements. But you must take them along with your calcium or else the calcium does not deposit where it should and can actually cause bone problems.
My doctor suggested 1 Viactive with vitamin D twice daily with the addition of 500 mg of vitamin D once a day as I was low normal for D.
If you take thyroid hormones you must not take calcium at the same time or it will cancel the thyroid hormone.
I love milk but somewhere along the line, I became lactose-intolerant (Mark Levin says he is too!)
I use those packets of Lactaid but sometimes they don't seem to work.
The gastroenterologist (sic>) I finally went to said “no more dairy”. He also said IBS. Could I be having more of the IBS instead of lactose-intolerance.
Anybody else know anything about getting lactose-tolerant? I miss milk big-time.
It seems that the association between vitamin D and a number of good health outcomes has been established. Enough so to warrant recommendation from many health professionals. But it looks like the health benefits are mostly long-term and difficult to confirm as proven.
Vitamin D is good, but be careful about taking mega doses of vitamin D (and especially if you are taking medicine for high blood pressure)
You can cause the dangerous condition of leeching too much calcium into your blood stream. bttt
Tip of the iceberg:
Introduction to Parathyroid Glands
High Blood Calcium.
High calcium in the blood is due to parathyroid disease almost all the time. High calcium (hypercalcemia) is never normal. All causes of high calcium are discussed here, including what tests will determine the cause of the high blood calcium. No worries, high blood calcium is rarely cancer! If you have high blood calcium, this is for you.
High blood calcium is not normal. If you have a blood test that shows high blood calcium, then your doctor is obligated to check it out. It is never normal to have high calcium levels in your blood. Hypercalcemia is the medical term for high blood calcium. This page is one of the first pages of Parathyroid.com that you should read if you just got back from the doctor and he/she told you that your blood calcium was too high. As you will see, over 98% of all cases of too much blood calcium are due to parathyroid disease and hyperparathyroidism. This page will list all of the causes of high blood calcium and discuss what tests are used to determine what is causing the high calcium. Keep reading. Editorial Note: Since we put this page on line we are getting more emails asking if your doctor should check you for cancer if your calcium is high. The answer is almost always NO. Parathyroid disease is the cause of high calcium at least 98% of the time. Measure parathyroid function first and you will find the reason for your high blood calcium.
IMPORTANT — There is a lot written about high calcium being caused by cancer, however, this is not very common. Let us say that again... It is very RARE for high blood calcium to be due to cancer. We know that if you search “high calcium” on the Internet you will find lots of web sites that talk about high calcium being caused by cancer... but relax, that’s just because there are a LOT more websites in the world discussing cancer than there are websites dedicated to parathyroid disease. HOWEVER, if you are sitting at a computer researching about your own high calcium, then you are almost guaranteed to NOT have cancer. Keep reading and you will see that people who are not in the hospital dying of cancer and have a high calcium on a blood test almost never have cancer and almost always DO have hyperparathyroidism. This must be fixed, but it is not cancer... its caused by a hormone problem. Now that you know you don’t have cancer... let’s read about all the causes of high blood calcium. Other areas of this web site tell you what to do about it.
Causes of High Blood Calcium and Too Much Calcium in the Blood.
High Blood Calcium Cause Number 1: Hyperparathyroidism (abnormal function of the parathyroid glands).
Over 99% of ALL people who have a blood test that shows too much calcium will have a parathyroid problem. The remainder of this site is about parathyroid disease, so you have come to the right place. We will not go into any detail about hyperparathyroidism on this page. Parathyroid glands are little glands in the neck that control the calcium in the blood. Occasionally one of them will grow into a benign tumor and cause high blood calcium. It is virtually 100% benign (not cancer), can be cured in most people (by expert surgeons) in under 20 minutes, and is almost always associated with some symptoms. If you have high calcium, you should start at the beginning of this site and read about your parathyroid problem. PARATHYROID DISEASE IS THE CAUSE OF ALMOST ALL HIGH CALCIUM LEVELS. IT MUST BE FIXED. IT SHOULD NOT BE IGNORED OR WATCHED. This is all we’ll say here... but we say lots on this web site! If you are sitting in front of a computer reading this page and your calcium is high, then you are almost guaranteed to have a parathyroid problem NOT cancer!
TESTS NEEDED: We discuss parathyroid disease on dozens of pages on this web site. In summary, you need to have your calcium and PTH measured... that’s it! Preferably, you should have TWO different types of blood calcium measured: 1) serum calcium, and 2) ionized calcium. Parathyroid Hormone (PTH) must also be measured. This is all that is needed to make the diagnosis of hyperparathyroidism in more than 95% of patients. You do NOT need any x-rays or scans to make the diagnosis of hyperparathyroidism. Scans are NOT to be used to determine if you have this disease. Go to the home page and read all the pages on parathyroid disease in order, or, the BEST page is our page on how to diagnose parathyroid disease.
High Blood Calcium Cause Number 2: Cancer (less than 1% of cases of high calcium are due to cancer... far less than 0.01% of cases of high calcium in people sitting in front of their computer are due to cancer) (you don’t have cancer!).
Cancer is a catch-all phrase that includes 122 different types of malignancies known to occur in humans. Of those 122 types of cancer, there are 5 that are known to be associated with high calcium levels in the blood. About 10% to 15% of people with one of these types of cancer will have a high calcium level at one time or another. Very high blood calcium (above 13) is the most common life-threatening emergency associated with these cancers, and is typically seen at the end-stage of the cancer (end-stage means the patient is in real bad shape and near the end). Thus, we can take several lessons away from these facts: 1) Cancer is almost never detected in a patient because the doctor noticed a high calcium level (this isn’t how cancers present themselves), 2) High calcium due to cancer almost always occurs in people who are quite sick from their cancer—its not a surprise that they have cancer, 3) High calcium due to cancer is usually found in people who are in the hospital—they are sick from the cancer, 4) if you have high calcium and you aren’t sick from cancer, then you are almost guaranteed to you have a parathyroid problem and not cancer.
The types of cancer known to be associated with high blood calcium are:
Multiple Myeloma (this is discussed separately below).
Lung Cancer (squamous cell cancer of the lung, not all lung cancers)
Breast Cancer (advanced disease)
Squamous Cell Cancer of the Head and Neck
Cancer causes hypercalcemia (high blood calcium) in two ways. The first is easiest to understand. Occasionally certain cancers will spread from their site of origin to other parts of the body. Some cancers (all those listed above) have a propensity to spread to the bone. This is called metastasis. When the metastatic cancer spreads to the bones it grows there and slowly eats away at the center of the bone—this releases calcium into the blood. The second way that some cancers can increase your blood calcium is via hormones and proteins that the tumor can secrete. One of these hormones is called “parathyroid-related-peptide”. These hormones can circulate in the blood and cause the bones to release calcium just like parathyroid hormone does. Some of our patients will have had a PTHrp test done prior to them being sent to us for parathyroid surgery. This is your doctor’s way of checking to make sure that your high calcium is not caused by a cancer. We do not require this test to be done, nor should you ask your doctor for it. In our opinion, this test is WAY over used (but at least you understand what it’s for). Do NOT ask for this test.
Multiple Myeloma. Multiple myeloma is a cancer (it is in the list above), but we write more about it here because it is the most common cancer cause of high calcium. Nearly half of all people with myeloma have hypercalcemia at some stage during their disease. Multiple myeloma is a cancer of the plasma cells (a type of white blood cell) that are found in the bone marrow. Plasma cells develop from B lymphocytes (a different type of white blood cell) and they produce antibodies that help the body fight infection (bacteria and viruses). When a plasma cell becomes malignant it will divide many times and produce many copies of itself that form tumors in the bone marrow. Over a period of years these tumor erode the inside of the bone, producing holes in the bones (called “lytic” lesions). Since the malignant cells are clones they all act exactly alike and they all produce the same antibody molecule that is secreted into the blood (this is what your doctor will measure).
Multiple myeloma is often detected during routine wellness testing where it shows up as an abnormally high amount of protein in the blood, a high calcium level, and often increased amounts of protein in the urine. To make the diagnosis your doctor will order a protein electrophoresis to be done. This test will examine the proteins in your blood to see if there is a large amount of one type of antibody present... and if there is, the diagnosis of multiple myeloma is made.
About 15% of patients that we see for parathyroid disease have had protein electrophoresis test performed to make sure they don’t have multiple myeloma prior to them coming for treatment of their parathyroid disease. We believe that this is NOT necessary and this test is performed way too often. This is often done by endocrinologists who do not see parathyroid patients very often and they order a BUNCH of tests on your first visit (shotgun approach). Remember, almost everybody with high calcium will have parathyroid disease. If your doctor does not order a protein electrophoresis on your first visit, then good for them. You are almost guaranteed to never need it and you have a good doctor.
High Blood Calcium Cause Number 3: Sarcoidosis
Sarcoidosis, or “sarcoid” for short, is a disease where the bodys immune system is over activated for unclear reasons. Sarcoid can often go many years before being detected, and is often found by accident when a chest x-ray is obtained for some other reason. Other patients can have symptoms such as cough or shortness of breath. Sarcoid often resolves spontaneously and therefore treatment is not always necessary. If a patient has symptoms the disease is usually treated with steroids. The cause of sarcoid is unknown. How sarcoid causes high calcium is not known, but is probably due to the same two ways that cancer causes increased calcium. This disease is very rare.
High Blood Calcium Cause Number 4: Excess Vitamin D Intake
Vitamin D is extremely important in helping maintain the balance of calcium in our bodies. In fact, that’s all that vitamin D does! Vitamin D has a direct effect on the intestines and encourages the intestines to absorb calcium from the food that you have eaten (this is why most milks are fortified with vitamin D). Vitamin D also has an effect on the kidneys and tells the kidneys to not let any calcium escape into the urine. Therefore, it is possible for a person to take too much vitamin D so that they absorb too much calcium from their diet and hold on to too much calcium in their kidneys... and their calcium goes high. In the real world, this does not really happen. Normal parathyroid glands won’t allow the calcium to go high.
I must tell you... although taking a bunch of Vit D so that you absorb lots of calcium from your diet which makes your blood calcium go high sounds quite plausible... it is so rare that it is hard for me to believe that I’m spending the time writing about it, and I’m sorry to waste the 20 seconds it took for you to read it. If you are taking dozens of vitamin D pills per day and your calcium goes high... then stop taking all the vitamin pills.
High Blood Calcium Cause Number 5: Certain Drugs
It is possible for certain drugs that people are prescribed for high blood pressure to have an effect on the kidney in such a way that the kidney doesn’t let enough calcium escape the blood into the urine... and the excess calcium shows up as a high blood calcium test. The one drug that is typically associated with this is HCTZ (hydrochlorothyazide) which is a “water pill” used for blood pressure. If you have high blood calcium and you are on this drug your doctor will probably take you off of this medicine and then re-check your blood in a few weeks. Almost all the time this is not the problem (it is very rare) and your blood calcium will continue to be high and you will have hyperparathyroidism (like more than 98% of people do who have high blood calcium). In reality, this “excuse” for high blood calcium is way over used and is 90% BS. Be careful of letting a doctor say that your blood calcium is high because you are on this blood pressure medicine. It can happen, but it is WAY over used as the excuse. It is MUCH more common for you to have a parathyroid problem and just coincidentally be on this very common drug. Be careful here, folks... this is a common mistake made that delays the diagnosis of parathyroid disease in at least 15% of all patients we see. Make sure your doctor doesn’t just “forget” about the high calcium and just blame it on this drug. That is a mistake almost all the time.
High Blood Calcium Cause Number 6: Milk-Alkali Syndrome.
Wow! Is it 1965 again? Milk-Alkali Syndrome is a phenomenon that occurs when a patient has a stomach ulcer and they self treat it by taking lots of antacids and drinking lots of milk. They do this so they can get relief of the pain in their stomach due to too much acid in the stomach. They buy lots of antacids like TUMS and eat lots of them. They also find that drinking milk makes their stomach feel better. However, the antacids have lots of calcium in them, and so does the milk. Therefore these people are eating LOTS of calcium every day and if it gets absorbed into the blood then they will have high blood calcium. Here is the good news... this is so rare these days that 99.99% of doctors will never see this in their lifetimes. Why??? Because we have lots better ways of treating stomach ulcers (Zantac, Prilosec, Nexium, Tagamet, etc, etc, etc). People don’t treat ulcers with antacids like they used to. It is a common mistake for doctors to blame a patient’s high blood calcium on eating too much calcium. Listen carefully... calcium is the most highly regulated element in our bodies because it runs our brain. NORMAL parathyroid glands will not allow people to have high blood calcium REGARDLESS of how much calcium they eat. If your doctor says “your calcium is high because you are eating too much dairy products and taking vitamins”, then you print this page and take it to him/her. Normal parathyroid glands will NOT let this happen...
High Blood Calcium Cause Number 7: Paget’s Disease of the Bone.
Paget’s Disease (osteitis deformans) is a chronic skeletal disorder that often results in enlarged or deformed bones in one or more regions of the skeleton. Excessive bone breakdown and formation can result in bone, which is dense but fragile. This continued bone breakdown can be a cause of hypercalcemia (too much calcium in the bone). It is extremely uncommon for Paget’s disease to be diagnosed after a patient had a routine blood test that showed a high calcium level. Thus, we put it on this page for completeness sake, but trust me, if you are on this page because you have a high calcium level in your blood... you don’t have this. For more about Paget’s Disease click here.
Smart Calcium Facts
Calcium, the fifth most common element in the body, exists almost entirely (99%) as crystalline hydroxyapatite in bones and teeth.
Calcium is used by nerve cells to propagate an impulse, and by muscle cells to contract. Humans want extremely regulated calcium levels because our brains (and entire nervous system) rely on calcium. If the calcium level in our blood is too high or too low, we get symptoms in our nervous system (click here to read more about symptoms of high calcium).
There are three ways that calcium is present in our blood: 1) protein-bound (45%); 2) attached to small diffusible anions such as citrate, lactate, phosphate and bicarbonate (10%); and ionized (45%).
Doctors almost always measure just one type of calcium (serum calcium). This is the calcium that gets measured when a routine “calcium” level is ordered. This measures the amount of all three types of calcium present in the blood and this is the only test that is needed almost all the time.
Ionized calcium is very important to measure in patients with hyperparathyroidism. Ionized calcium relates to the symptoms a patient will have with hyperparathyroidism. If your calcium is high normal then make sure your ionized calcium is measured since many people with hyperparathyroidism will have serum calcium levels that are normal, but their ionized calcium levels are high. It is the ionized calcium levels that make people feel bad! The problem is that most doctors aren’t aware that ionized calcium should be measured in parathyroid patients, and very few understand that the symptoms parathyroid patients get are related to high ionized calcium levels. If your doctor doesn’t believe your high calcium level is causing you symptoms... print this and ask him/her to measure your ionized calcium.
Hypercalcemia is defined as a serum calcium concentration above 10.4 mg/dL (2.6 mmol/L in Canada, Europe, and Asia). A serum calcium concentration >14.0 mg/dL (>3.5 mmol/L) requires immediate therapy. Although there are many causes of hypercalcemia, primary hyperparathyroidism is the most common cause in the general population, and cancer and other non-PTH-mediated causes are most common in hospitalized patients.
If you are sitting in front a computer and you have high calcium, then the odds of you having hyperparathyroidism as the cause of your high calcium is about 99.9%. The odds of one of the other problems (like cancer) listed above being the cause of your high calcium is near zero. Stop worrying, and don’t let your doctor do all sorts of silly tests looking for cancer. You have hyperparathyroidism until proven otherwise. It is easy to fix, and must be fixed.
Parathyroid Hormone Related Peptide (PTHrp) is not a perfect test to determine who’s high calcium is due to cancer and who’s is not. About 3% of normal people will have a high PTHrp and, 8% of people with hyperparathyroidism will have a high level. On the flip side, 12% of people with hypercalcemia due to cancer will have normal PTHrp levels (it should be high). Thus, this test like all tests have a specific error rate. Please don’t print this page and take it to your doctor demanding that this test be done. It is way over used!
If you want to read more about calcium levels in the blood, how to diagnose parathyroid disease, and look at a graph of normal and high calcium levels, then go to our page on Diagnosing Parathyroid Disease. This page has some very nice graphs. Remember, you don’t have cancer, you almost certainly have hyperparathyroidism which is easy to fix. Spend some time here and learn about parathyroid glands. Remember, an expert surgeon should be able to fix this problem in about 20 minutes or less. Also, you may want to go to our home page and start from the beginning.
If you want to learn more about calcium and you learn well from watching videos, then watch Dr Norman give a short talk on “ What is calcium and why is it so important?”
This page was last updated 11/13/2010
June 11, 2011
Vitamin D Toxicity
Can too much vitamin D be harmful? Yes, it certainly can - though anything can be toxic in excess, even water. As one of the safest substances known to man, vitamin D toxicity is very rare. In fact, people are at far greater risk of vitamin D deficiency than they are of vitamin D toxicity.
What is vitamin D toxicity?
Vitamin D toxicity is a condition where blood serum concentrations of vitamin Ds storage form, 25(OH)D or calcidiol, become too high, causing adverse systemic effects.
How it happens
There is no risk of vitamin D toxicity due to sun exposure.
Because the body has a built in mechanism for preventing toxicity with vitamin D produced in the skin, there is no risk of vitamin D toxicity due to ultraviolet-B (UVB) exposure - whether from the Sun or a tanning bed.
Supplemental vitamin D bypasses this built-in protection and, if excessive amounts are consumed over a period of time, 25(OH)D blood levels can reach a point where toxicity is possible.
What exactly constitutes a toxic dose of vitamin D has yet to be determined, though it is possible this amount may vary with the individual.
Published cases of toxicity, for which serum levels and dose are known, all involve intake of > or = 40000 IU (1000 mcg) per day. 1 Two different cases involved intake of over 2,000,000 IU per day - both men survived. 2 3
Serum levels: upper limit and toxicity threshold
Upper limit for a substance is the amount up to which is considered safe and without risk of adverse effects in the majority of the population.
Toxicity threshold for a substance is the amount beyond which over-saturation occurs and symptoms of toxicity manifest.
These values for 25(OH)D are as follows:
Toxicity threshold level - 200-250 ng/mL (500-750 nmol/L) 4 5 6 7 8
Upper limit - 100 ng/mL (250 nmol/L)
The large range between 25(OH)Ds upper limit and its threshold value implies a degree of safety at serum levels up to 100 ng/mL (250 nmol/L), since concentrations twice this amount have yet to ever be associated with toxicity. 4
In animal models, serum concentrations have reached as high as 400-700 ng/mL (1,000-1750 nmol/L) before toxic effects (severe hypercalcemia) were observed. 8 9
Symptoms: toxicity and overdose
Signs of vitamin D toxicity are high urine and blood calcium.
The first sign of vitamin D toxicity is hypercalcuria (excess calcium in the urine) followed by hypercalcemia (high blood calcium). The following symptoms may present:
constipation (possibly alternating with diarrhea)
tingling sensations in the mouth
heart rhythm abnormalities
The immediate symptoms of vitamin D overdose are:
What to do if you think you are vitamin D toxic
Vitamin D is not toxic when used in the amounts Nature intended.
It is fairly difficult to become toxic using vitamin D3. If you think you may be toxic because you are having an adverse reaction to vitamin D but you have not been using excessive amounts like those described above, your symptoms could be due to reasons other than toxicity.
Test serum levels
First thing is to stop supplementation, then have your physician help you determine if you are toxic by testing your 25(OH)D levels. This is the same test used to determine vitamin D deficiency.
Rule out other possibilities
If results indicate levels lower than 200-250 ng/mL (500-750 nmol/L), you are most likely not toxic. In this case, the reaction you experienced may be a result of:
An underlying magnesium deficiency. This is the most common reason for symptoms brought on by using vitamin D.
Vitamin D hypersensitivity due to pre-existing high blood calcium (hypercalcemia). Often mistaken for vitamin D toxicity, hypercalcemia is a rare condition usually caused by one of the following:
primary hyperparathyroidism (most common cause)
If toxic, reduce serum levels
If the results show a serum 25(OH)D level of 200-250 ng/mL (500-750 nmol/L) or more, you could be toxic. The following measures should be taken until vitamin D levels return to normal:
avoidance of direct sunlight exposure
avoidance of foods and supplements containing vitamin D
restriction of calcium intake
drinking 8 glasses of water daily
Once 25(OH)D levels have normalized, sunlight exposure and/or vitamin D supplementation can be resumed, taking care not to overdo it.
In most cases, vitamin D toxicity can be corrected without lasting problems, provided the body has not remained in a hypercalcemic state for too long. Hypercalcemia has the potential to cause soft tissue calcification, resulting in deposits of calcium crystals in the heart, lungs, and/or kidneys. With prolonged hypercalcemia, permanent damage is possible if calcification is severe enough.
Page last edited: 11 June 2011
Vieth, R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr. 1999 May; 69 (5): 842-56.
Koutkia, P. Chen, T. C. Holick, M. F. Vitamin D intoxication associated with an over-the-counter supplement. N Engl J Med. 2001 Jul 5; 345 (1): 66-7.
Los Angeles Times Supplements guru sues over his own product. 2010/4/29;
Jones, G. Pharmacokinetics of vitamin D toxicity. Am J Clin Nutr. 2008 Aug; 88 (2): 582S-586S.
Heaney, R. P. Vitamin D: criteria for safety and efficacy. Nutr Rev. 2008 Oct; 66 (10 Suppl 2): S178-81.
Vieth, R. Vitamin D toxicity, policy, and science. J Bone Miner Res. 2007 Dec; 22 Suppl 2V64-8.
Vieth, R. Critique of the considerations for establishing the tolerable upper intake level for vitamin D: critical need for revision upwards. J Nutr. 2006 Apr; 136 (4): 1117-22.
NIH Office of Dietary Supplements Dietary Supplement Fact Sheet: Vitamin D. 2009/11/13;
Deluca, H. F. Prahl, J. M. Plum, L. A. 1,25-Dihydroxyvitamin D is not responsible for toxicity caused by vitamin D or 25-hydroxyvitamin D. Arch Biochem Biophys. 2010 Oct 18;
Two things I do re: lactase insufficiency: 1) Drink the new chocolate milks that are lactose-free (these are great). 2) Use Digestive Advantage Lactose Defense Formula (tablets) which keeps lactase in your system all the time, top to bottom. Works better than the supplements that have to “go down with the food”. I have IBS also. Gastroenterologists are pretty useless except for giving colonoscopies.
Consumer Reports May, 2011 issue
The vitamin D dilemma
How much is too much? What you should know about getting tested.
Last reviewed: May 2011
Vitamin D is hotand not just because it comes from the sun. Once prescribed only to prevent or treat outright vitamin D deficiency, rickets, and osteoporosis, doctors have increasingly recommended vitamin D supplements to treat or try to prevent a lengthy list of ills, including autism, certain cancers, diabetes, heart disease, multiple sclerosis, respiratory infections, and cognitive decline in seniors.
Prompted by news reports of vitamin D’s benefits and a perception that they don’t have enough of it, an increasing number of consumers have been asking doctors to test their vitamin D levels. As a result, sales of vitamin D have skyrocketed to $425 million in 2009 from just $40 million in 2001, according to the Nutrition Business Journal.
But is vitamin D worth the hype? A recent report by the Institute of Medicine found that the news media and medical profession overreacted to the cascade of studies in the last decade associating low levels of vitamin D with numerous ailments. The institute’s November 2010 report, which examined more than 1,000 studies and other reports, concluded that vitamin D was essential for bone growth and maintenance but that the evidence of its benefits beyond that was inconclusive.
Since most cells in the body have receptors for vitamin D, its potential involvement in other diseases, such as cancer, is a tantalizing area of research but one that requires more in-depth, large-scale studies. “We don’t understand the mechanism for how it might prevent these diseases, or how much is needed,” says Frank Greer, M.D., a professor of pediatrics at the University of Wisconsin.
Most of us aren’t deficient
Much of the evidence for vitamin D comes from population studies, which have suggested a positive relation between high blood levels of the vitamin and a reduced risk of disease. But they haven’t proved a cause and effect. Since vitamin D can be created by exposure to sunlight and is usually higher in people who are thinner, it could be that people who have high levels of the nutrient tend to exercise more or have healthier weights.
And there is confusion over what constitutes vitamin D deficiency. The IOM report challenged the notion of a widespread deficiency of the vitamin or of the mineral calcium. So why do people think they’re deficient? One explanation is that most testing laboratories have changed their definition of a “normal” blood level. The lower limit used by many was 20 nanograms per milliliter; now anything under 30 ng/ml is considered an insufficient amount.
While some people truly are deficient in vitamin D, the report concluded that the average American is not. Even assuming minimal sun exposure, the panel found that people are probably consuming adequate amounts of both vitamin D and calcium because they take multivitamins and eat food that has been fortified with those nutrients.
The report’s recommendationsthat children and most adults get 600 international units of vitamin D a day, and people older than 70 get 800 IUwere more than the targets set 14 years ago (200 IU a day for adults ages 19 to 50, 400 IU for those older than 50, and 600 IU for those older than 70). But they fall far short of the daily intake recommended by some expertsup to 3,000 IU a day for people living in areas such as the Northeast.
Failed promises of other supplements
There are good reasons to be cautious before embracing a nutrient’s potential until rigorous testing has been done.
JoAnn Manson, M.D., Dr.P.H., a Harvard Medical School professor who is also chief of preventive medicine at Brigham & Women’s Hospital in Boston and a member of the IOM committee, points to the failed promise of supplements of vitamins C and E and the nutrient beta carotene, as well as hormone therapy in women. All of them were at one time thought to prevent cancer or heart disease but didn’t withstand the scrutiny of clinical trials. Some studies even suggested that they could be harmful at high levels, increasing the risk of lung cancer (among smokers taking beta-carotene pills), and the potential for heart failure, hemorrhagic strokes, and even death for those taking as little as 400 IU of vitamin E a day.
“These all looked beneficial in observational studies,” Manson says. “But when subjected to rigorous testing, they were shown not to be of benefit.”
Trials for vitamin D are ongoing, including one that Manson is leading involving 20,000 healthy older Americans. The trials will examine whether taking 2,000 IU of vitamin D a day can lower the risk for heart disease, stroke, or certain cancers. “We expect the benefits will outweigh the risks, but we don’t know conclusively,” she says.
Is vitamin D a special case?
Other experts argue that the IOM’s report is overly cautious and that there is no downside to increasing vitamin D levels. “The good news is, they recognized that the recommendations in 1997 were woefully inadequate, and they increased them threefold, which is quite remarkable for any nutrient,” says Michael Holick, Ph.D., M.D., a professor of medicine, physiology, and biophysics at the Boston University School of Medicine and the author of “The Vitamin D Solution” (Hudson Street Press, 2010). “But they didn’t go far enough.” He recommends that his patients try to achieve vitamin D blood levels of 40 to 60 ng/ml, an amount that typically requires a total of 3,000 IU a day.
But Consumer Reports Health doesn’t agree with that advice for a number of reasons. The IOM report set the upper limit for vitamin D at 4,000 IU for those 9 and older, after which the risk for harm begins to increase. At very high levelsabove 10,000 IU a daythere’s a risk of kidney and tissue damage.
According to the IOM, a vitamin D blood level above 50 ng/ml should raise concerns about potential adverse effects, which some evidence suggests could include raising the risk for other diseases, such as pancreatic cancer.
And with many proponents of vitamin D arguing for elevating levels into the 40-to-60 ng/ml range for the general population, some experts emphasize the need to be more vigilant.
“People tend to think that if one pill might be good, then maybe a handful would be better,” says Tim Byers, M.D., M.P.H., a cancer epidemiologist and associate dean of the Colorado School of Public Health in Denver. “But our experience with this teaches us that caution is needed when taking large doses of supplements. Sometimes we don’t discover the harms of supplements until we’ve accumulated a large enough number of subjects and studies.”
For African-Americans, taking vitamin D supplements could even be counterproductive. Last year a study by the Wake Forest University School of Medicine involving 340 African-Americans with type 2 diabetes found that those with the highest vitamin D levels (few of whom were taking calcium or vitamin D supplements) were more likely to have calcified plaque in their major arteries, a predictor of heart attack and stroke.
Barry I. Freedman, M.D., the study’s lead author and chief of the section on nephrology there, says that this was the opposite of what occurred in white patients, indicating that the accepted “normal” range of vitamin D might differ among races. He points out that African-Americans have markedly lower rates of osteoporosis and have less calcium deposited in their large arteries compared with whites, despite their lower vitamin D levels.
“We need to determine whether we should be targeting the same vitamin D level in blacks as whites, and better understand the cardiovascular effects of supplementing vitamin D in African-Americans,” he says.
Should you be tested?
Our medical consultants say that the evidence suggests that screening as part of a routine regular exam is not yet justified.
Instead, it should generally be limited to people who have some objective evidence or reason that they might be vitamin D deficient, such as having markedly weak bones, celiac disease, or other ailments that impair the body’s ability to absorb the vitamin from food.
It’s less clear whether testing makes sense for people who are at slightly increased risk of low levels because they are overweight, don’t get much sun exposure, or eat little vitamin-D rich foods. If they choose testing, they should know that the benefits are less certain for them and that insurance will be less likely to cover the cost, which can range from $40 to almost $300.
What you should know about testing
For adequate bone health, your blood level of vitamin D should be at least 20 ng/ml, a level that would protect at least 97.5 percent of the population against adverse skeletal effects, such as fractures, and ensure healthy bones. Inadequate intakes are diagnosed when levels dip well below 20.
“Doctors are using what clinical labs define as deficient,” notes Patsy Brannon, Ph.D., R.D., a professor of nutritional sciences at Cornell University and a member of the IOM panel. “We have people getting lab values back at 29, being diagnosed as insufficient, and being given extremely high doses for fairly long periods of time. You could easily wind up with blood levels approaching 50 ng/ml.”
Adding to the challenge of interpreting your results are these factors:
Vitamin D levels change with the seasons, exposure to sunlight, and dietary intake.
There is no standardization of vitamin D tests, which means results can differ from one lab to another.
If you decide to be tested, ask whether it will be done in-house or sent to a reference lab, where the volume of tests can be much higher and the accuracy probably better. “Tests like vitamin D are mostly manual and are prone to shifts and bias, which are only observed if one performs at least more than 50 a day,” says Ravinder Singh, Ph.D., co-director of the endocrine lab at the Mayo Clinic.
If the results of your test are abnormal or unexpected, you should be retested. If you are found to be deficient, your doctor will probably recommend an oral dose of 50,000 IU of vitamin D once a week for 8 to 12 weeks. After that, maintenance might require 400 to 800 IU depending on your diet. In general, for every 100 IU of vitamin D you take in, there is an increase of roughly 1 ng/ml in the blood level of vitamin D.
Advice can change as studies are completed. “The intakes are not set in stone,” says Clifford Rosen, M.D., of the Maine Medical Center Research Institute in Scarborough and a member of the IOM Committee. “If you want a kind of insurance policy in case we find a positive effect later, supplementation is not harmful at low doses.”
Until research confirms the benefit of higher doses, stick with the IOM’s recommendation: 600 IU for adults up to age 70 and 800 IU for those older than 70. Look for a vitamin D product with the “USP Verified” mark, which means it meets standards of quality, purity, and potency set by the nonprofit U.S. Pharmacopeia. For better absorption of the vitamin, take it with a meal containing some fat. Good food sources of vitamin D include cod-liver oil, cooked button mushrooms, eggs, fortified milk and soy products, mackerel, sardines, and wild Alaskan or sockeye salmon.
If you get some midday sun exposure during the warmer months and regularly consume vitamin D-rich foods, you probably don’t need supplements. People who are middle-aged or otherwise at risk of vitamin D deficiency, including those who are overweight or have darker skin, might need supplements. Even then, the amount in most multivitamins is probably enough.
This report was made possible by a grant from the Airborne Cy Pres Fund, which was established through a legal settlement of a national class-action lawsuit (Wilson v. Airborne Health, Inc., et al.) regarding deceptive advertising practices.
Consumer Reports June 8, 2011
Vitamins & Supplements
Vitamin D screening for everyone? Not so fast
Jun 8, 2011 12:20 PM
If your doctor suggests measuring your blood levels of vitamin D at your next physical, ask why, particularly if youre not at-risk for vitamin D deficiency.
New guidelines from the Endocrine Society, released online this week, say the screening is generally necessary only for individuals at risk for deficiency. That echoes our recent advice on vitamin D testing.
The new guidelines from the Endocrine Society suggested specific dietary intakes of vitamin D as well as treatments for specific at-risk groups, including infants, children, obese adults, older adults, and pregnant women. It recommends against using supplementation to prevent cardiovascular disease or death or to enhance quality of life. For the most part, the vitamin D levels suggested in the Endocrine Societys guidance mirror the amounts recommended by the Institute of Medicine last fall. However, the Societys guidance provides more detail on how to treat someone with an established vitamin D deficiency.
The average American is not deficient in vitamin D and consumes adequate amounts through supplements or foods, according to the IOM.
On the other hand, our medical consultants say those at risk for deficiency could benefit from having their blood levels of vitamin D tested. That includes people with markedly weak bones and those with celiac disease or other ailments that impair the body’s ability to absorb the vitamin from food. Its less clear is whether testing makes sense for people who are at slightly increased risk of low levels because they are overweight, don’t get much sun exposure, or eat little vitamin-D rich foods.
Bottom line: Before you get your vitamin D level measured, ask your doctor why you might need to. In terms of how much you vitamin D you should aim for, from food and supplements, stick with the IOM’s recommendation: 600 IU for adults up to age 70 and 800 IU for those older than 70. Foods that naturally contain or are fortified with vitamin D include cod-liver oil, button mushrooms, eggs, fortified milk and soy products, mackerel, sardines, and wild Alaskan or sockeye salmon.
If you opt for a supplement, look for a product with the “USP Verified” mark, which means it meets standards of quality, purity, and potency set by the nonprofit U.S. Pharmacopeia. If you get some midday sun exposure during the warmer months and regularly consume vitamin D-rich foods, you probably don’t need supplements. People who are middle-aged or otherwise at risk of vitamin D deficiency, including those who are overweight or have darker skin, might need supplements. Even then, the amount in most multivitamins is probably enough.
Read more about vitamin D deficiency and testing. bttt
I meant to say “regular and chocolate milk”. Both are available without lactose. But with the Digestive Advantage product it seems I can have moderate quantities of ordinary milk as well (just regular glasses, no big mugs — afraid to try that).
I’ve been drinking 2~3 gallons of mik (sometimes more) a week since forever. I don’t know what I’d do if I couldn’t drink it.
I’m in favor of vitamin D supplementation but all known or suspected of things should get a hearing.
In fact, you need to wait four hours before taking calcium.
Due to hypoparathyroidism after thyroid cancer surgeries, I'm stuck with needing calcium and active vitamin D along with thyroid meds for the rest of my life. Had to learn the hard way what not taking some at all or taking them at the wrong time means.
But on the other hand, taking active vitamin D regularly has been very beneficial for me. Rarely get sick from colds or flus anymore. Knocking down chances for other cancers works for me, too.