The Truth About Vitamin D

Does Vitamin D Reduce Risk Of Heart Disease & Cancer?

Author: Dr. Stephen Chaney

 

the truth about vitamin dYou have every right to be confused. One day you are told that vitamin D reduces your risk of heart disease and cancer. The next day you are told vitamin D makes has no effect on those diseases. You are told vitamin D is a waste of money. What should you believe?  What is the truth about vitamin D?

In mid-November a major clinical study called VITAL was published. It examined the effect of vitamin D and omega-3s on heart disease and cancer risk. Last week I wrote about the omega-3 portion of the study. This week I will cover the vitamin D portion of the study.

Once again, if you rely on the media for your information on supplementation, you are probably confused. Headlines ranged from “Vitamin D Is Ineffective For Preventing Cancer And Heart Disease to “Vitamin D Lowers Odds Of Cancer Death.” What is the truth?

The problem is that reporters aren’t scientists. They don’t know how to interpret clinical studies. What they report is filtered through their personal biases. That is why I take the time to carefully evaluate the clinical studies, so I can provide you with accurate information. Let me sort through the dueling headlines and give you the truth about vitamin D, cancer, and heart disease.

How Was The Study Designed?

the truth about vitamin d studyThe VITAL study (JE Manson et al, New England Journal of Medicine, DOI: 10.1056/NEJMoa1811403) enrolled 25,871 healthy adults (average age = 67) in the United States. The study participants were 50% female, 50% male, and 20% African American. None of the participants had preexisting cancer or heart disease. The characteristics of the study group were typical of the American population at that age, namely:

  • The average BMI was 28, which means that most of the participants were significantly overweight.
  • 7% of them had diabetes.

Study participants were given questionnaires on enrollment to assess clinical and lifestyle factors including dietary intake. Blood samples were taken from about 65% of the participants to determine 25-hydroxyvitamin D levels (a measure of vitamin D status) at baseline and at the end of the first year. The participants were given either 2,000 IU of vitamin D/day or a placebo and followed for an average of 5.3 years.

There were two important characteristics of the participants in this study that may have influenced the outcome.

  • The average 25-hydroxyvitamin D level of participants at the beginning of the study was 31 ng/ml (78 nmol/L). The NIH considers 20-50 ng/ml (50-125 nmol/L) to be the optimal level of 25-hydroxyvitamin D for most physiological functions. This means that study participants started in the middle of the optimal range with respect to vitamin D status.

[Note: The NIH defines the 20-50 ng/ml range as “adequate.”  However, I know many of my readers like to aim beyond adequate to reach what they consider to be “optimal.”  In the case of vitamin D, that might not be a good idea. The NIH considers anything above 50 ng/ml as associated “with potentially adverse effects.”  For that reason, I will refer to the 20-50 ng/ml range as optimal for this article. I wouldn’t want to encourage my readers to be aiming for above 50 ng/ml.]

  • Only 12.7% of participants had 25-hydroxyvitamin D levels below 20 ng/ml, which the NIH considers to be inadequate. The results with this group were not statistically different from the study participants with optimal vitamin D status, but it is not clear that there were enough people in this subgroup for a statistically valid comparison with participants starting with an optimal vitamin D status.
  • At the end of the first year, 25-hydroxyvitamin D levels in the treatment group increased to 42 ng/ml (105 nmol/L), which is near the upper end of the optimal range. Thus, for most of the participants, the study was evaluating whether there was a benefit of increasing vitamin D status from the middle to the upper end of the optimal range.
  • The study allowed subjects to continue taking supplements that contained up to 800 IU of vitamin D. While the authors tried to correct for this statistically, it is a confounding variable.

Does Vitamin D Reduce The Risk Of Cancer?

 

the truth about vitamin d and cancerYou may remember from last week that omega-3s were more effective for reducing heart disease risk than for reducing cancer risk. What is the truth about vitamin D and cancer risk?   The results are reversed for vitamin D, so I will discuss cancer first.

The study reported that vitamin D supplementation did not reduce a diagnosis of invasive cancer of any type, breast cancer, prostate cancer, or colon cancer during the 5.3-year time-period of this study. This was the result that was reported in the abstract and was what lazy journalists, who never read past the abstract, reported.

However, the rest of the study was more positive. For example, occurrence of invasive cancer of any type was reduced by:

  • 23% in African-Americans.
  • 24% in patients with a healthy body weight.

Several previous studies have suggested that vitamin D may be more effective at preventing cancer in people with a healthy body weight, but the mechanism of this effect is currently unknown.

Most previous studies have not included enough African-Americans to determine whether they respond more favorably to vitamin D supplementation. However, African-Americans have a higher risk of cancer, so this finding deserves follow-up.

In addition, when the study looked at deaths from cancer, the results were very positive. For example:

  • Cancer deaths during the 5.3-year study period were reduced by 17%.
  • The longer vitamin D supplementation was continued the more effective it became at reducing cancer deaths. For example,
  • When the authors excluded cancer deaths occurring during the first year of supplementation, vitamin D reduced cancer deaths by 21%.
  • When the authors excluded cancer deaths occurring during the first two years of supplementation, vitamin D reduced cancer deaths by 25%.

Finally, no side effects were noted in the vitamin D group.

 

Does Vitamin D Reduce The Risk Of Heart Disease?

 

the truth about vitamin d and heart diseaseThe VITAL study also looked at the effect of vitamin D on heart disease risk. What is the truth about vitamin D and heart disease?  The results from this study were uniformly negative. There was no effect of vitamin D supplementation on all major cardiovascular events combined, heart attack, stroke, or death from heart disease. Does that mean vitamin D has no role in reducing heart disease risk? That’s not clear.

The authors had a thought-provoking explanation for why the results were negative for heart disease, but positive for cancer. Remember that the participants in this trial started with a 25-hydroxyvitamin D level of 31 ng/ml and increased it to at least 42 ng/ml with vitamin D supplementation.

The authors stated that previous studies have suggested the 25-hydroxyvitamin D level associated with the lowest risk for heart disease is between 20 and 25 ng/ml. If that is true, most of the participants in this trial were already in the lowest possible risk for heart disease with respect to vitamin D status before the study even started. There would be no reason to expect additional vitamin D to further reduce their risk of heart disease.

In contrast, the authors said that previous studies suggest the 25-hydroxyvitamin D level associated with the lowest risk of cancer deaths is above 30 ng/ml. If that is true, it would explain why vitamin D supplementation in this study was effective at reducing cancer deaths.

However, previous placebo-controlled clinical studies have also been inconclusive with respect to vitamin D and heart disease. My recommendation would be to think of adequate vitamin D status as part of a holistic approach to reducing heart disease – one that includes a heart-healthy diet and a heart-healthy lifestyle – rather than a “magic bullet” that decreases heart disease risk by itself.

As for heart-healthy diets, I discuss the pros and cons of various diets in my book, “Slaying The Food Myths.”  As I discuss in my book, the weight of scientific evidence supports primarily plant-based diets that include omega-3s as heart healthy. As an example, the Mediterranean diet is primarily plant-based and is rich in healthy oils like olive oil and omega-3s. It is associated with reduced risk of both heart disease and cancer.

 

What Is The Truth About Vitamin D?

 

the truth about vitamin d signThere is a lot of confusion around the question of whether vitamin D reduces the risk of cancer. This study strengthened previous observation suggesting that vitamin D supplementation decreases cancer deaths. However, it is also consistent with previous studies that have failed to find an effect of vitamin D on cancer development. How can we understand this apparent discrepancy? The authors provided a logical explanation. They pointed out that:

  • Cancer development takes 20-30 years while this clinical study lasted only 5.3 years. That means that vitamin D supplementation only occurred at the tail end of the cancer development process. In fact, the cancer was already there in most of the patients in the study who developed cancer. It just had not been diagnosed yet. In the words of the authors: “Given the long latency for cancer development, extended follow-up is necessary to fully ascertain potential effects [of vitamin D supplementation].”
  • In contrast, none of the patients had been diagnosed with cancer when they entered the trial. That means that the patients were diagnosed with cancer during the 5.3-year study period. They were receiving extra vitamin D during the entire period of cancer treatment. Thus, the effect of vitamin D on reducing cancer deaths was easier to detect.

What Does This Study Mean For You?

the truth about vitamin d questionsVitamin D Is Likely To Decrease Your Risk Of Dying From Cancer: When you combine the results of this study with what we already know about vitamin D and cancer, the results are clear. Vitamin D appears to reduce your risk of dying from cancer. More importantly, the longer you have been supplementing with vitamin D, the greater your risk reduction is likely to be.

Vitamin D May Decrease Your Risk Of Developing Cancer: Association studies suggest that optimal vitamin D status is associated with decreased cancer risk, especially colon cancer risk. However, the long time for cancer development means that we may never be able to prove this effect through double-blind, placebo-controlled clinical trials.

Holistic Is Best: When you combine the VITAL study results with what we already know about vitamin D and heart disease, it appears that supplementing with vitamin D is unlikely to reduce your risk of developing heart disease unless you are vitamin D deficient. However, a holistic approach that starts with a healthy, primarily plant-based diet and makes sure your vitamin D status is adequate is likely to be effective.

The same is likely true for cancer. While the latest study suggests that vitamin D supplementation reduces your risk of dying from cancer, those vitamin D supplements are likely to be even more effective if you also adopt a healthy diet and lifestyle.

How Much Vitamin D Do You Need? The optimal dose of vitamin D is likely to be different for each of us. One of the things we have learned in recent years is that there are significant differences in the efficiency with which we convert vitamin D from diet and/or sun exposure into the active form of vitamin D in our cells. Fortunately, the blood test for 25-hydroxyvitamin D is readily available and is widely considered to be an excellent measure of our vitamin D status.

I recommend that you have your blood level of 25-hydroxyvitamin D tested on an annual basis. Based on the best currently available data, I recommend you aim for >20 ng/ml (50 nmol/L) if you wish to minimize your risk of heart disease and >30 ng/ml (75 nmol/L) if you wish to minimize your risk of cancer. If you can achieve those levels through diet and a multivitamin supplement, that is great. If not, I would recommend adding a vitamin D supplement until those levels are achieved.

Finally, you shouldn’t think of vitamin D as a magic bullet. If you are a couch potato and eat sodas and junk food, don’t expect vitamin D to protect you from cancer and heart disease. You should think of maintaining adequate 25-hydroxyvitamin D levels as just one component of a holistic approach to healthy, disease-free living.

 

The Bottom Line

 

There is a lot of confusion around the question of whether vitamin D reduces the risk of cancer and heart disease. A major clinical study has just been published that sheds light on these important questions. It reported:

  • Vitamin D did not decrease the risk of developing cancer during the 5.3-year study duration. The authors pointed out that cancer takes 20-30 years to develop, which means their study was probably too short to detect an effect of vitamin D on the risk of developing cancer.
  • Vitamin D did decrease the risk of dying from cancer, and the longer people were supplementing with vitamin D the bigger the protective effect of vitamin D was.
  • Vitamin D did not decrease the risk of heart disease. However, most study participants had a level of 25-hydroxyvitamin D that was optimal for reducing the risk of heart disease at the beginning of the study. There was no reason to expect that extra vitamin D would provide additional benefit.
  • With respect to both cancer and heart disease the best advice is to:
    • Get your 25-hydroxyvitamin D levels tested on an annual basis and supplement, if necessary, to keep your 25-hydroxyvitamin D levels in what the NIH considers to be an adequate range (20-50 ng/ml).
    • We do not have good dose response data for the beneficial effects of vitamin D on heart disease and cancer. However, according to this article, previous studies suggest you may want to am for 25-hydroxyvitamin D levels above 20 ng/ml to reduce the risk of heart disease and above 30 ng/ml to reduce your risk of cancer.
    • Consider vitamin D as just one component of a holistic approach to healthy, disease-free living.

For more details about the interpretation of these studies and what they mean for you, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

 

Does Vitamin D Reduce Cholesterol In Children?

Is Vitamin D Associated With Heart Disease Risk?

Author: Dr. Stephen Chaney

 

vitamin-d-reduce-cholesterol-childrenNot too many years ago, we thought of vitamin D as affecting bone density and little else. Then we discovered that almost every cell in our body has vitamin D receptors. This has lead to research suggesting that vitamin D affects our health in many ways that were unimaginable only a couple of decades ago.

For example, low vitamin D levels are associated with increased risk of heart disease. The linkage between vitamin D and heart disease has not been proven. Nor do we know the mechanism. However, this has lead to ongoing research asking if there is any relationship between vitamin D and cholesterol metabolism.

The answer appears to be yes. Several studies have suggested a correlation between low vitamin D levels and elevated total cholesterol, LDL cholesterol, and triglycerides – all risk factors for heart disease.

The next question is how early in life is this correlation found. Again, some studies have suggested that the same correlation between low vitamin D and high levels of unhealthy lipids are found in teens. But, what about pre-teens, children who haven’t gone through puberty yet? That’s what this study was designed to determine.

 

How Was The Study Done?

vitamin-d-reduce-cholesterol-children studyThe current study  was based on data collected from 419 children, ages 6-8, in the Physical Activity and Nutrition in Children (PANIC) Study in Eastern Finland. This was a lifestyle study that collected information on body weight, diet, and activity levels.

Fasting blood samples were also collected and analyzed for blood lipid levels (total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides) and for 25-hydroxyvitamin D (25(OH)D), which is considered the most accurate measure of vitamin D status. The National Institutes of Health considers:

  • <30 nmol/L of 25(OH)D an indicator of vitamin D deficiency.
  • 30 to <50 nmol/L 25(OH)D an indicator of vitamin D insufficiency.
  • ≥50 nmol/L 25(OH)D an indicator of adequate vitamin D status.

To put this study in perspective, vitamin D status is a major concern in Finland because of its proximity to the Arctic Circle. There is little sunlight in the winter, and, although the days are long in the summer, the sun is weak. The major sources of vitamin D in the Finnish diet are fish, vitamin D-fortified fluid milk products, vitamin D-fortified fat spreads, and vitamin D supplementation. Vitamin D fortification was introduced in Finland in 2003. Vitamin D supplementation has also become increasing popular. The number of people using vitamin D supplements has increased from 11% in 2000 to 41% in 2011.

A recent study  looking a vitamin D status between 2000 and 2011 found that the combination of food fortification and vitamin D supplementation has been successful at improving vitamin D status in the Finnish population, increasing average 25(OH)D levels from 48 nmol/L to 65 nmol/L.

 

Does Vitamin D Reduce Cholesterol In Children?

vitamin dIn this study the mean serum 25(OH)D in the children was 68.1 nmol/L. 20% of the children had serum 25(OH)D below 50 nmol/L, and only 4 children (1%) had serum 25(OH)D below 30 nmol/L. When 25(OH)D levels were compared with blood lipid levels:

  • Higher serum 25(OH)D levels were associated with lower plasma levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides.
  • The association between higher 25(OH)D levels and lower blood levels of total cholesterol, LDL cholesterol, and HDL cholesterol remained after correcting for weight, physical activity, sedentary behavior, diet, daylight time, parental education, and genetic mutations known to affect vitamin D metabolism.

What Does This Mean For You?

I don’t want to overinterpret the study. Not all studies show an inverse association between 25(OH)D and cholesterol levels. Most of the previous studies have also indicated that higher 25(OH)D levels were associated increased HDL levels, while this study found higher 25(OH)D levels associated with decreased HDL levels. Much more research needs to be done.

However, this study is yet another indication that optimal vitamin D status may be important for heart health, even in young children. While the correlation between vitamin D status and heart health is not definitive at present, virtually everyone agrees that adequate vitamin D status is a good thing.

My recommendations are to:

  • Get as much vitamin D as possible from vitamin D-fortified foods, oily fish, and sensible sun exposure.
  • Get your serum 25(OH)D level determined and take vitamin D supplements if it is low.

 

The Bottom Line

 

A recent study of vitamin D status in Finnish children ages 6-8 found:

  • Higher vitamin D status was associated with lower plasma levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides.
  • The association between better vitamin D status and lower blood levels of total cholesterol, LDL cholesterol, and HDL cholesterol remained after correcting for weight, physical activity, sedentary behavior, diet, daylight time, parental education, and genetic mutations known to affect vitamin D metabolism.

This study is another indication that optimal vitamin D status may be important for heart health, even in young children. While the correlation between vitamin D status and heart health is not definitive at present, virtually everyone agrees that adequate vitamin D status is a good thing.

My recommendations are to:

  • Get as much vitamin D as possible from vitamin D-fortified foods, oily fish, and sensible sun exposure.
  • Get your serum 25-hydroxyvitamin D level determined and take vitamin D supplements if it is low.
  • Make sure your children are getting enough vitamin D in their diet and have optimal serum 25-hydroxyvitamin D.

For more details, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Does Vitamin D Help Prevent Asthma Attacks?

Author: Dr. Stephen Chaney

breaking newsWhat do the experts say about vitamin D helping to prevent asthma attacks?  You’ve seen the headlines. Vitamin D is no longer just for healthy bones. It has become the latest “miracle” nutrient. If you believe everything you read, vitamin D can prevent or cure everything from multiple sclerosis to diabetes, heart disease, and cancer. Unfortunately, the evidence for many of those claims is weak.

However, the effect of vitamin D on the severity of asthma symptoms appears to be an exception. That relationship appears to be on much more solid ground.

A review published last year(S.K. Bantz et al, Annals of Pediatrics and Child Health, 3: pii: 1032, 2015) concluded “We emphasize that all children, especially those who are asthmatic, should be assessed to ensure adequate intake or supplementation with at least the minimum recommended doses of vitamin D. The simple intervention of vitamin D supplementation may provide significant clinical improvement in atopic disease, especially asthma.” [Note: Atopic disease refers to diseases characterized by a hyperallergenic response, such as eczema, hay fever, and asthma.]

That was followed by the recent publication of a Cochrane Review  that concluded “Vitamin D is likely to offer protection against severe asthma attacks”. To understand the significance of that statement you need to understand that this is not just another clinical study or another review. Cochrane Reviews are conducted by an international group of experts and are considered the “Gold Standard” for evidence-based medicine.

You may remember that famous commercial: “When E.F. Hutton speaks, people listen.”  In this case: “When Cochrane Reviews speak, doctors listen.”

Let’s look briefly at how the review was conducted, and then examine exactly what the review said, and what it didn’t say.

Does Vitamin D Help Prevent Asthma Attacks?

certifiedOne of the characteristics of Cochrane Reviews that set them apart from many of the other reviews that you find in the literature is that they include only the highest quality clinical studies in their analysis. This is one of the things that gives them such credibility.

This particular Cochrane Review included seven trials involving a total of 435 children and two trials involving a total of 658 adults. Most trial participants had mild to moderate asthma. The duration of the trials ranged from four to 12 months.  All studies were placebo controlled and used close to RDA recommended doses of vitamin D.

The results were pretty clear cut:

  • Vitamin D supplementation reduced the average number of severe asthma attacks requiring treatment with oral steroids by 36%.  This conclusion was based on 3 high-quality studies involving 680 participants.  Here, these studies clearly show vitamin D does  help prevent asthma attacks.
  • Vitamin D supplementation reduced the number of acute asthma attacks requiring emergency room visits and/or hospitalizations by 50%. This conclusion was based on 7 high-quality studies with 963 participants.  These studies also show vitamin D helps prevent asthma attacks.
  • None of the studies reported any severe adverse effects from vitamin D supplementation. (Compare that with all warnings associated with those ads for asthma medications you see on TV.)

However, they did not see any effect of vitamin D supplementation on day-to-day asthma symptoms.

What Does This Study Mean For You?

prevent asthmaThis study strongly suggests that vitamin D supplementation in the RDA range (600 IU for ages 1-70 and 800 IU for adults over 70) significantly reduces the risk of severe asthma attacks requiring steroids or hospitalization. Thus, if you or your child have asthma, vitamin D supplementation in the RDA range just makes sense.

However, this study also suggest that vitamin D is not a panacea that will make all asthma symptoms disappear.

Also, even Cochrane Reviews have limitations.

  • None of the studies included in this review looked at vitamin D status prior to the study. We simply don’t know whether vitamin D supplementation might be effective at reducing day-to-day asthma symptoms in individuals who were vitamin D deficient.
  • The studies included in this review did not include asthma sufferers with severe symptoms. Again, we don’t know whether vitamin D supplementation might make day-to-day symptoms more tolerable and easily controlled for people with severe asthma symptoms

One final thought: Blood levels of 25-hydroxy-vitamin D are the best indicators of vitamin D status. For reasons that we don’t understand, not everyone consuming RDA levels of vitamin D ends up with optimal levels (50-75 nmoles/L).  For that reason, it is a good idea to get your blood levels of 25-hydroxy-vitamin D tested as part of your annual physical exam.

If you are already getting RDA levels of vitamin D and your 25-hydroxy-vitamin D levels are not in the optimal range, you may want to supplement with extra vitamin D.  Just be sure to monitor your 25-hydroxy-vitamin D levels on a regular basis to make sure they don’t exceed the optimal range.

So, according to the Cochrane Review, vitamin D does help prevent asthma attacks.

 

The Bottom Line

 

  • A recent Cochrane Review concluded that vitamin D supplementation in the RDA range (600 IU for ages 1-70 and 800 IU for adults over 70) significantly reduces the risk of severe asthma attacks requiring steroids or hospitalization in both children and adults. This is significant because Cochrane Reviews are considered the Gold Standard for evidence-based medicine.
  • Thus, if you or your child have asthma, vitamin D supplementation in the RDA range just makes sense.
  • However, blood levels of 25-hydroxy-vitamin D are the best measure of vitamin status, and not everyone consuming RDA levels of vitamin D ends up with optimal levels (50-75 nmoles/L). If you are already getting RDA levels of vitamin D in your diet and your 25-hydroxy-vitamin D levels are not in the optimal range, you may want to supplement with extra vitamin D. Just be sure to monitor your 25-hydroxy-vitamin D levels on a regular basis to make sure they don’t exceed the optimal range.
  • This Cochrane Review did not find any effect of vitamin D supplementation on day-to-day asthma symptoms.
  • However, even Cochrane Reviews have limitations.
  • None of the studies included in this review looked at vitamin D status prior to the study. We simply don’t know whether vitamin D supplementation might be effective at reducing day-to-day asthma symptoms in individuals who were vitamin D deficient.
  • The studies included in this review did not include asthma sufferers with severe symptoms. Again, we don’t know whether vitamin D supplementation might make day-to-day symptoms more tolerable and easily controlled for people with severe asthma symptoms

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Skin Damage From Sun

Author: Dr. Stephen Chaney

skin damage from sunSkin damage from sun is a real danger.  The dog days of summer are here. For some of us that means staying inside as much as possible. Others want to enjoy the fleeting days of summer as much as possible before summer turns to fall, and fall turns to winter. That means lots of outdoor activities in the sun – such as outdoor sports, working in the yard, and vacations in fun locations with lots of sun. So it’s time to ask the perennial question “How much sun exposure should I be getting?”

Some people like to aim for as much sun exposure as possible. When I was a teenager everybody was searching for “the perfect tan”. Back then it was popular to slather your skin with tanning oils that allowed you to just baste yourself in the sun without your skin drying up. (Did I just date myself again?)

Other people like to follow their dermatologist’s advice and use SPF maximum (the sun shall never touch my skin) sunscreens. And, just to be on the safe side they also follow their dermatologist’s advice to limit sun exposure between 10 AM and 4 PM and wear a hat, sunglasses, and protective clothing whenever possible. I can see the hat and sunglasses, but the protective clothing isn’t particularly compatible with the summer heat in my native North Carolina. Believe me, you want to wear as little as possible here in the summer.

Skin Damage From Sun

sun exposureNow that we’ve explored the extremes, let’s return to the central theme of this health tip which is “How much sun exposure should I really be getting?” Let’s start by focusing on the vanity factor – skin aging. Let’s face it. Excessive sun exposure increases the risk of skin cancer. However, skin aging is the consequence most people really care about. This is the concern that has most people reaching for the sunscreen before they head out the door.

A recent clinical study clearly showed that sunscreen usage helps prevent skin aging (Hughes et al, Annals of Internal Medicine, 158: 781-790, 2013). Now you might be saying to yourself “This is nothing new. I’ve heard that for years.” Yes, that advice has been around for a long time. But the problem is that the old advice was never based on actual clinical studies, only studies done on hairless mice. So first, let me analyze this clinical study for you and then put the findings into perspective.

The good news is that this was a very well done clinical study. The authors enrolled 903 adults under the age of 55 from sunny Australia into the study for a 4.5-year period from 1992 to 1996. The study was restricted to adults younger than 55 years because, in that age range, skin aging is primarily caused by sun exposure rather than the normal aging process. The study also excluded people who were already using sunscreen on a daily basis. Variables such as skin color, skin reaction to sun exposure, amount of time spent outdoors, sunburn history, and smoking status were determined at baseline and used to normalize the results.

Half of the participants were given a sunscreen with an SPF 15 factor and were instructed to use this sunscreen on a daily basis. The other half were given nothing and were just instructed to keep doing what they had been doing (It was deemed unethical to give them a placebo sunscreen as it could cause skin damage from sun). Compliance was assessed by measuring the weight of the returned sunscreen bottles every three months and by using a biennial application frequency questionnaire. Compliance wasn’t perfect, but of those enrolled in the sunscreen portion of the study 77% used sunscreen 3 to 4 times per week, compared to 33% of the control group.

Skin damage from sun was assessed by taking an impression of the back of the left-hand and analyzing it for the number and depth of lines and the flattening of the skin. And the results were fairly clear-cut. Those study participants who used sunscreen on a daily basis had 24% less sun damage over the 4.5-year period than the control group. I am not an expert, but dermatologists who have evaluated this study say that a 24% decrease in sun damage is visibly significant.

What Does This Study Mean For You?

It turns out that the old advice that too much sun exposure can cause significant skin damage as we get older is actually true. Who would have guessed? If the threat of skin cancer isn’t enough to dissuade you from pursuing the perfect tan, perhaps the thought of ugly, wrinkled skin as you get older will do it.

On the flip side, however, we need to remember that sun exposure is also required for vitamin D formation. And recent studies show that up to 80% of Americans have low levels of 25-hydroxy vitamin D, the biologically relevant form of vitamin D, in their blood – perhaps because many of us actually follow our dermatologist’s advice and never go out of the house without sunscreen, sunglasses, hat, and protective clothing to help prevent skin damage from sun.

Recent clinical studies have linked low levels of 25-hydroxy vitamin D with a number of health concerns. That has led one prominent dermatologist who studies vitamin D, Dr. Michael Holick, to recommend that we should be getting 10 to 15 minutes of unprotected sun exposure during midday – a recommendation that many of his colleagues consider to be heretical.

How Can You Have Your Cake And Eat It Too?

vitamin DSo what is a person to do? How can we reconcile the need to improve our vitamin D status with our desire to have a healthy, good looking skin well into our golden years? The simple answer is to make sure that we are getting plenty of vitamin D in our diet. The most recent RDAs are 600 IU per day of vitamin D in children and adults up to the age of 70 and 800 IU per day for adults over 70.

Many experts are even recommending that we get 1000 to 2000 IU of vitamin D per day. The Institute of Medicine (the group that actually sets the RDAs) considers that to be in the safe range for vitamin D intake. If you are thinking of exceeding that dosage, my advice would be to first get your 25-hydroxy vitamin D levels determined (20-50 ng/ml or 50-125 nmol/L is considered optimal) and then consult with your doctor as to what the best dosage of vitamin D is for you.

And, if you are relying on supplements for your vitamin D intake, you should be sure to choose a company that manufactures their supplements according to pharmaceutical standards. A recent study(E. S. LeBlanc et al, JAMA Internal Medicine, 173:585-586, 2013)  analyzed commercially available vitamin D supplements and found some brands in which the potency from bottle to bottle ranged from 9% to 140% of what was on the label. That is unacceptable.

 

The Bottom Line

  • A recent study has confirmed what we have been told for years, namely that regular use of an SPF 15 sunscreen reduces skin aging. Specifically, the study showed that regular sunscreen use reduced skin aging by 24% over a 4.5-year period in people 55 years old or younger.
  • On the other hand, sun exposure is required for our bodies to synthesize the active form of vitamin D. Vitamin D experts like Dr. Michael Holick recommend that we get at least 10-15 minutes of unprotected sun exposure a day during the summer months to assure that our bodies make the vitamin D we need for optimal health.
  • If you want both young looking skin and optimal vitamin D status, you will probably want to consider a vitamin D supplement. Recommendations for how much and what kind of vitamin D supplement are found in the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.