Food & Fitness After 50: Beware of Online Advice to Take Vitamin D or Zinc to Prevent COVID-19

Dietary supplements can help fill nutrient gaps or be used to treat deficiencies but lately I’ve seen lots of headlines implying supplements of vitamin D and zinc can make you immune to COVID-19. In a word? NO.

To top it off, many well-meaning people are touting these nutrients on their social media feeds with messages like, “wash your hands and take loads of vitamin D and zinc,” or “stock up on vitamins and minerals, they are natural so you can’t take too much.” Ouch. Hemlock is a natural poison, so clearly you can take too much of a “natural” substance.

vitaminddiscVitamin D

What do these headlines have in common?

  • Vitamin D deficiency may be linked to more severe cases of COVID-19.
  • New study claims vitamin D deficiency may impact coronavirus mortality rates.
  • Could vitamin D deficiency and coronavirus be connected?
  • New study suggests vitamin D is linked to COVID-19 mortality.
  • Coronavirus: How vitamin D could keep you healthy during the pandemic.

I’ve underlined the key words to give you a clue. These headlines are from the same study. The study found a relationship, not a cause and effect, with vitamin D and the virus. When you see the words or phrases like “appears to play a role,” “may be linked,” “may impact,” “suggests,” “related to,” or “associated with,” it tells you about a relationship between two things. It doesn’t tell you that one thing caused another. Did you know there is a strong relationship between the increase in bottled water consumption and rising rates of obesity in the U.S.? Clearly, it doesn’t mean that bottled water is “causing” obesity.

In addition to the well-recognized role in bone health, Vitamin D is important in immunity. It helps modulate the immune system, making immune cells less inflammatory. Various groups, from the Institute of Medicine (IOM is a nonprofit organization and part of The National Academies that works outside the framework of government to provide evidence-based research and recommendations for public health and science policy) recommends that all adults age 51 to 70 years get 600 IU (equal to 15 micrograms or mcg) a day and those over the age of 70 get 800 IU a day (20 mcg). The Endocrine Society suggests adults need 1000 to 1500 IU to ensure adequate blood levels of the vitamin.

It is hard to get enough vitamin D from food and older adults are at risk for insufficiency because skin doesn’t make vitamin D from sunlight as efficiently with aging. Many adults turn to vitamin D supplements to get the needed vitamin D.

And, we started this post with suggestions that the vitamin plays a role in COVID-19. At this point, it is only speculation, but there are at least nine clinical trials listed on ClinicalTrials.gov, exploring various aspects on the vitamin on the virus. A rapid review paper from University of Oxford in the UK (click here for the paper), published May 1, found that currently is there is no clinical evidence to support prevention or treatment of COVID-19 with vitamin D

The Bottom Line?

  • If you have had your blood levels of vitamin D measured by your doctor and she or he has recommended a supplement, continue to take the dose as recommended.
  • If you have not had a vitamin D blood test, don’t self-diagnose and start taking vitamin D.
  • If you take a multivitamin/mineral supplement you may be getting the recommended amount or slightly higher for vitamin D; multis formulated for “seniors” often contain 1000 IU of vitamin D. Don’t take any more than the Upper Limit of 4000 IU/day unless prescribed by an MD.
  • Best food sources of vitamin D are fatty fish; think salmon, tuna, sardines. We know eating fish is good for our health in many ways, so include a fish meal at least twice a week.

Zinc 

Picture1We have no storage site in the body for zinc, so it is needed in the diet every day. Zinc is better known for its role in inhibiting the common cold virus from sticking and replicating in the nose and throat. It can also stop inflammation that contributes to the symptoms of a cold…runny nose and stuffy head.

There is no research on using zinc for COVID-19.

While there are many zinc preparations in the cold and flu cold aisle of your local drug or grocery store, should you use them? The research results are mixed, of course, they often are, but the latest review from the Cochrane Collaboration (a group that reviews medical topics by reviewing many studies on a particular topic) found that when zinc is taken at the first sign of a cold the length of the illness is reduced by about one day.

When using it for warding off a cold, keep in mind the following:

  • Timing and dose are important, try one zinc lozenge at the first sign of a cold and take it every 4 hours (most have 10 to 15 milligrams of zinc per dose).
  • More isn’t better, in fact, in can make things worse; nausea and vomiting can occur if you take too much and it can leave a metal taste in the mouth.
  • Avoid zinc nasal sprays…the Food and Drug Administration warned consumers that zinc sprays can lead to changes in the sense of smell and sometimes permanent changes.
  • Zinc can interfere with some prescription medications, like antibiotics and blood thinners, so always consider potential drug interactions.

The Bottom Line?

  • Zinc is important for a healthy immune system but there is no evidence at this time that it will protect against COVID-19.
  • Too much zinc, which is easy to get in supplement form, can cause nausea and vomiting.
  • The Upper Limit for zinc is 40 milligrams so keep that in mind if you use zinc lozenges.
  • Aim for zinc-rich foods every day. Good choices are seafood (oysters, lobster, crab), beef, pork, poultry, baked beans, and fortified breakfast cereals.

I asked Connie Diekman, registered dietitian, food and nutrition consultant, and former President of the Academy of Nutrition and Dietetics to help sum it up:

“With this new virus, much is unknown which makes it more important that we depend on the science related to supplements, rather than opinions posted by a variety of people. The body of evidence related to vitamins and minerals is extensive, while the knowledge behind Covid-19 is evolving. Therefore, as an RD, the best advice I’d give is to focus on a well-balanced eating plan and talk to your MD or RD to determine if you would benefit from supplements – don’t go it alone!”

Dr. Christine Rosenbloom is a registered dietitian nutritionist and a nutrition professor emerita at Georgia State University in Atlanta. Along with Dr. Bob Murray, she is the author of Food & Fitness After 50.

Copyright © 2019 [Christine Rosenbloom]. All Rights Reserved

 

Food & Fitness After 50: Good Bones

A recent article in the Washington Post caught my attention because it related to an issue that older adults frequently ask about….how to protect their bones as they age.

Hip-Fracture-Surgery-Infection-640x444According to the study published in JAMA vitamin D supplements showed no effect on reducing hip fractures where as vitamin D plus calcium had about a 16% reduction in the risk of breaking a hip. Hip fracture is one of the most serious threats to health as we age. Here’s a few facts from the Centers for Disease Control and Prevention.

  • Each year over 300,000 older people—those 65 and older—are hospitalized for hip fractures.
  • More than 95% of hip fractures are caused by falling, usually by falling sideways.
  • Women experience three-quarters of all hip fractures.
    • Women fall more often than men.
    • Women more often have osteoporosis, a disease that weakens bones and makes them more likely to break.

Dietary Supplement Use for Bone Health

A recent survey from the Council on Responsible Medicine, a leading trade association for dietary supplements, shows that among consumers over 55 years of age who take dietary supplements, 31% cite bone health as a reason for supplementation. For younger age groups, bone health is not mentioned as a reason for supplementation. That is too bad because the time to build bone is when we are young! Peak bone mass is achieved somewhere around the age of 30 or 35 so waiting until you are 60 to start worrying about bone health is a bit too late. It’s like getting concerned about your cholesterol level after you’ve had a heart attack. (Side note to my older readers…encourage your grandchildren and great grandchildren to get plenty of bone building nutrients now!)

boneMass35Anthony Thomas, Director of Scientific Affairs for Jarrow Formulas puts it this way, “Maximizing peak bone mass is important when we are young to protect against age-related bone loss.  A 10% increase in peak bone mass is estimated to reduce the risk of osteoporotic fracture later in life by 50%, so early life deserves more attention to ensure sufficient nutrient intake and status to support bone health across the lifespan.”

It Takes More Than Calcium and Vitamin D to Make a Healthy Bone

natto
Natto

While the media focuses on calcium and vitamin D, Dr. Thomas reminds us that bone is more than those two nutrients. Healthy bones need the minerals magnesium, potassium, copper, manganese, silicon, boron, and zinc. Two underappreciated vitamins are also key, vitamins C and K. Vitamin C is needed to produce collagen, the most abundant protein in the body and building block of bone. Vitamin K helps calcium get deposited into bones. There are two forms of vitamin K, referred to as K1 and K2. K1 is most well-known for its role in blood clotting. But the K2 form promotes bone building. It is hard to get sufficient K2 from foods. Dr. Thomas points out that “vitamin K2 is from bacterial origin, so it is found in fermented foods in which bacteria are used as starter cultures in cheeses and sauerkraut.  The best dietary source of vitamin K2 in the form of MK-7 is the traditional Japanese dish natto, cooked soybeans fermented by the bacteria Bacillus subtilis subspecies natto, that while popular in Japan, is not much appreciated in the U.S.“ The best way to get this form of the vitamin is with supplements sold as MK-7.

“Based on emerging research, the supplemental doses used in research is a daily dose of vitamin K2 as MK-7 is 45 micrograms upwards of 360 micrograms is recommended,” adds Dr. Thomas.

Fall Protection

While foods and supplementation can help provide nutrients for healthy bones, don’t forget the ABCs (agility, balance, and coordination) as keys to help preventing falls. We’ve written about this before (click here for the post), but it pays to work on your balance with activities like yoga, Tai Chi, or simple exercises such as balancing on one foot when you brush your teeth. When it comes to balance, we can use it….or, we can lose it!

Check out this video from Silver Sneakers for easy exercises to improve your balance

For more information on foods and supplements for bone health and tips to improve your agility, balance, and coordination, see Food & Fitness After 50, available at Amazon and other booksellers.

Copyright © 2019 [Christine Rosenbloom]. All Rights Reserved.

Food & Fitness After 50: Research Roundup

Each day dozens of research studies appear in my inbox, peaking this old college professor’s interest. Last week, there were three studies that made me want to take a closer look: one published in an aging journal, one presented at an annual scientific conference, and one animal study in the journal Brain Structure and Function.  Let’s briefly talk about each one and how it might translates from the page to your plate.

Blueberries for Blood Pressure

1200-136890271-blueberriesThe blue color in blueberries is due to the presence of anthocyanins (pronounced ann-though-sigh-a-nins), a sub-group of plant chemicals knows as polyphenols. Fruits and veggies that are deeply colored red, blue, and purple are especially rich in anthocyanins. The study published in the Journals of Gerontology (gerontology is the study of aging) found that eating about a cup of blueberries twice a day lowered blood pressure similar to the lowering from taking common blood pressure meds. The effect on blood pressure was both acute (happened quickly) and chronic (over time). Researchers found that the anthocyanins relaxed blood vessels and reduced the stiffness that occurs in aging blood vessels. As we age, our blood vessels lose their elasticity making it harder to control blood pressure and increasing our risk for heart disease.

What does in mean for you?

Eat more blueberries! One cup of berries, whether fresh or frozen, has about 60 calories, making it a low-calorie addition to your diet. What it doesn’t mean is taking a blueberry concentrate supplement (yes, they do exist). Researchers note that blueberries are also rich in vitamins, minerals, and fiber and the synergistic action between them and the anthocyanins might also be a reason for their health promoting powers. So, food beats supplements!

Pomegranate: Can it juice your memory?

pom wonderfulPomegranate juice is rich in polyphenols called ellagitannins (pronounced eee-laj-ah-tan-ins). These antioxidant compounds are in plants to protect the plant, but when we eat the plant, their protectors come along for the ride. The research, presented at the 2019 meeting of the American Association for Geriatric Psychiatry, described how a daily serving of pomegranate juice improved visual learning and retention of learning in a year-long study with older adults, average age of 60. The study was a randomized, placebo-controlled, double-blind study; a design that is considered the gold standard in nutrition research. What that means is that study participants were randomly assigned to either drink 8-ounces of pomegranate juice or 8-ounces of drink that looked and tasted like pomegranate juice but contained none of the active polyphenols. Double-blind means that neither the participant nor the researchers knew who was getting the real juice or the placebo. Dr. Gary Small, director of the University of California (UCLA) Longevity Center, presented the current research at the scientific conference, building upon similar work that his group published in 2013 in the Journal of Evidence-Based Complementary and Alternative Medicine. In the 2013 study, a similar design was used but the study was short-term, only lasting one month, but the results were similar. So, the researchers wanted to know if a longer-term study would show memory benefits, and it did.

Researchers are not sure exactly what it is in the pomegranate juice that showed the positive results. One interesting theory is that the pomegranate juice works though the gut microbiome. The healthy bacteria in our gut can breakdown the ellagitannins to a compound that crosses the blood brain barrier, exerting its beneficial effect through the gut-brain axis.

What does it mean for you?

An eight-ounce bottle of pomegranate juice contains 2 whole pomegranates, so drinking the unsweetened juice gives you 650 to 700 milligrams of polyphenols. That’s a lot of good stuff in a little bottle. Pomegranate juice is tart, not sweet, so it might appeal to those of you who don’t like sweet, sugar-added beverages. Considering that most of us don’t eat enough fruit, 8-ounces of pomegranate juice is a good way to get more fruit and healthy polyphenols in our diet.

Vitamin D: Good for the Brain?

Vit DThe third study is on vitamin D deficiency on processing new information and retaining it for future recall. It was conducted with mice and I always cautioned my students to count the legs on the research subjects before considering if it is relevant to those of us on two legs, but this study is interesting in understanding vitamin D deficiency and the brain. Vitamin D is most often thought of as a bone-building nutrient because without enough vitamin D only 10-15% of dietary calcium is absorbed. Yet, vitamin D has many roles in the body, including cognition.

Older adults are considered “at risk” for vitamin D deficiency because our skin doesn’t convert sunlight to vitamin D as readily as it did when we were younger and vitamin D isn’t found naturally in a lot of foods. Some foods, like milk, are fortified with vitamin D, but many yogurts are not. (The only way to know if your favorite yogurt is fortified with vitamin D is to read the nutrition facts panel and ingredient list on the container.)  The recommended dietary allowance for vitamin D is 600 IU for those 51 to 70 years and 800 IU for those over 70. The upper limit is 4000 IU and many older adults take a supplement of 1000 IU to make sure they are getting enough vitamin D. Check with your doctor and ask if a vitamin D blood test is needed to tailor your vitamin D intake to your blood level.

What does it mean for you?

Choose vitamin D-rich foods, either naturally occurring or fortified (for an extensive list of vitamin D in foods click here.)

Bottom Line

Eat more deeply colored fruits and veggies, including blueberries and pomegranate juice, to get healthy plant compounds in your diet. And, choose vitamin D rich foods, like salmon or tuna, and fortified milk, yogurt, and cereals. Here is my breakfast plan:

  • 1 cup of Greek yogurt (choose a brand fortified with Vitamin D)
  • 1 cup of fresh or frozen blueberries and ½ cup of high fiber breakfast cereal mixed into yogurt
  • 8-ounces of pomegranate juice

While the research is promising, this breakfast may or may not improve my brain health, but it gives me a great start to the morning with three servings of fruit and a good dose of fiber in a calcium and vitamin D-rich breakfast bowl. And, did I mention it tastes great?

For more information on how foods and fitness affect brain health check out Food & Fitness After 50.

Copyright © 2019 [Christine Rosenbloom]. All Rights Reserved.

Disclosure, I am on a clinical nutrition advisory board for POM Wonderful, but I was not asked to write about pomegranate juice or compensated to write this post. 

Supplements: Help or Hype or Hope?

This post is a summary of information from a talk I gave at the Bell Family Branch YMCA in Hartwell, GA on April 12th and 30th, 2018.

Broccoli and pillsAre you among the 76% of Americans who take dietary supplements?  And, if you are  in the 55+ population, are you one of the 80% who take supplements? The most popular supplements are multi-vitamins, vitamin D, vitamin C, calcium, and B-complex.

This post will cover multi-vitamins and minerals; next week we’ll cover muscle-building and weight loss supplements.

How much do you really know about the supplements you are taking? Dietary supplements are a profitable business with a $40 billion annual market. Supplements are regulated by the Food & Drug Administration, but not as well as many people would like them to be. In 1996, the Dietary Supplement Health & Education Act put supplements in a new category, unlike  food additives or drugs, supplements do not undergo testing to make sure they are

  • pure
  • safe
  • or that they work before coming to market

More people are more worried about artificial sweeteners, which undergo rigorous safety testing, than dietary supplements, which are lacking in safety testing.

What is a supplement?

Dietary supplements include thousands of products that fall into these categories:

  • Vitamins: such as vitamin D or C
  • Minerals: like calcium or magnesium
  • Herbs or botanicals: such as St. John’s Wort or echinacea
  • Amino acids: like branched chain amino acids or arginine
  • Dietary substances: like glucosamime or curcumin
  • Concentrates or extracts: such as green tea extract or resveratrol

Decoding a supplement label

All supplements must have a supplements facts panel, similar to a nutrition facts panel found on food packages. And, supplement makers can make claims called structure-function claims: things like, “supports heart health,” “supports bone health,” or “supports muscle health. “But they can’t say “prevents heart attack,” “treats low bone density,” or “will make your muscles grow like Arnold Schwarzenegger’s.”  Any time there is a health claim you will find this statement (usually in small print):

“This statement has not been evaluated by the Food & Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”

Interesting, because many of us take supplements to treat, cure, or prevent disease!

Beware of testimonials

The promotional materials for supplements can make all sorts of outrageous claims. As showcased in this article from Center for Science in the Public Interest, testimonials abound and many use identical testimonials to make your think that real people are praising the value of the supplements, when in fact they are paid advertisements.

Multivitamin mineral supplements

Since multis are the most popular dietary supplement, let’s look at what you need to know.

First, look for an age-appropriate supplement: adults over 50 have somewhat different nutrient needs than younger adults. “Silver” vitamins or vitamins for “50+ for her” or “50+ for him” are formulated to meet your needs. Multivitamin-mineral supplements are safe, relatively cheap, and can fill gaps in your nutrient intakes. But, they may also be unnecessary. (Supplement users have healthier habits that those who don’t take supplements: they tend to eat better, get more exercise, and more likely to be non-smokers.) And, multis don’t provide everything you need. For example, no multi provides all of the calcium you need.

Some things to consider fall into my “don’t” list:

  • Older adults should not take a pre-natal vitamin, unless they are pregnant. Pre-natal vitamins are formulated to support the health of the baby and mother. They contain higher amounts of many nutrients, including iron, that are not needed in large amounts as we age.
  • Avoid adult gummies or chewables: they don’t measure up to pill or capsule forms and many contain far less than the recommended levels of nutrients and may be lacking trace minerals such as zinc, magnesium, or chromium.
  • Don’t fall for special “immunity,” “muscle function,” “heart health,” “energy,” or even “healthy appearance” claims. These are more expensive and just not necessary.

Resources for more information on vitamin and minerals

My “go to” source for learning about vitamin and mineral supplements, updated research, as well as food sources, is the Office of Dietary Supplements at the National Institutes of Health. On this site, you will find a wealth of information on individual nutrients: here is a link to the consumer information on vitamin D, to show you an example.

And, in our book, Food & Fitness After 50, we provide more information on supplements that might be helpful in specific disease conditions.

Look for next week’s post on muscle building and weight loss supplement!

Chris Rosenbloom, along with co-author, Bob Murray, talk about supplements and much more in Food & Fitness After 50.

 

 

Calcium and Vitamin D are still important!

The Institute of Medicine Report was published yesterday and I watched the national news outlets do the report a disservice–those darn sound bites just can’t capture the complexity of the report. (The complete report can be found on the IOM website http://www.iom.edu/).

The report concluded that there is not enough evidence to increase the recommended intakes for vitamin D or calcium but that is far from saying that we don’t need these 2 critical nutrients for bone health. Most people don’t get the recommended amounts of these nutrients in their diets but that message was lost in the reporting. I would not want women of any age to abandon their efforts to get calcium from their diet or supplements. I always recommend food first and there are more foods with added calcium–from orange juice to breakfast cereals–available in the grocery store. A recent study looked at calcium intake in post menopausal women and found that dairy foods were the number one source of calcium for white women but grains contribued the most calcium to the diets of black women.

Older women who don’t get enough calcium should use calcium citrate supplements–they are better absorbed than calcium carbonate supplements as we age. But, more isn’t better and I think that is what the report was trying to stress.

The more controversial part of the report was on Vitamin D; this nutrient is also crucial for bone health–nobody disagrees with that–but there are also claims that this sunshine vitamin also plays a role in diabetes, heart disease, auto-immune diseases and some cancers. It is not surprising to me that the report did not find a strong link with Vitamin D and other disorders because the research is emerging and no conclusions can be reached. Science moves slowly but the media reports every little study as if a cure for every disease was as simple as popping a supplement. The hype is often well ahead of the science.

So, don’t throw away your supplements–make sure to get adequate, not excessive, calcium and vitamin D in your diet and then add what is missing from supplements. Remember that supplements are meant to supplement diet–not replace it.

Cancer Survivors and Lifestyle Changes

October is Breast Cancer Awareness month and I just reached survivor status this month by being cancer-free for 5 years. The American Cancer Society estimates that there are 11 million cancer survivors and by the year 2020 there will be 20 million of us.

Every cancer survivor celebrates beating cancer but also worries about it coming back. The good news is that simple lifestyle changes can stack the odds in your favor. Try these 5 things to help fight your cancer from coming back.

1) Be active every day. Exercise can help control your weight and excess weight increases levels of estrogen and insulin–two hormones that fuel cancer cells. Exercise also fights other chronic diseases like diabetes, high blood pressure, and osteoporosis.

2) Eat and least 5 servings of fruit and vegetables every day. It is easier than it sounds because a small glass of juice, blueberries on your breakfast cereals, a veggie-packed salad at lunch, and an apple gives you the 5 servings needed for good health. One on my favorite quick dinner meals is a saute of veggies (green and red peppers, broccoli, asparagus, and onions) with olive oil and tossed with spaghetti noodles and sprinkled with fresh grated Parmesan cheese. Yummy and a 2 to 3 serving of vegetables meal.

3) Decrease or eliminate processed meats–no more bologna (I grew up on bologna and fried bologna sandwiches were a staple in my family), bacon, sausage or processed luncheon meats.

4) Get more the of the sunshine vitamin–vitamin D. This nutrient is showing promise as a cancer fighting vitamin. Ask your doctor to check your vitamin D level to get a baseline before you start supplementing with vitamin D pills. But eat vitamin-D rich foods every day such as fatty fish and dairy foods fortified with vitamin D. Yogurt is a popular dairy food for its calcium and protein but did you know that not all yogurt has vitamin D? Turn the carton over and look for vitamin D and don’t be surprised if you find zero vitamin D in your yogurt. The exception? Yoplait yogurt has 20% of the daily value of vitamin D in a serving so kudos to Yoplait. And, Yoplait also is a big supporter of breast cancer research–their save the lids campaign benefits Susan G. Koman for the Cure and so far they raised over $1.6 million from this year’s campaign. So dig your spoon into that!

Forty ng/mL? That is the level of vitamin D (also called serum 25(OH)D3) in my blood but what does it mean? Vitamin D is one of the most talked about nutrients and for good reason–along with calcium it is critical for building and maintaining healthy bones, but vitamin D is also one of the most confusing vitamins. We can get vitamin D three different ways:

  • through foods (although very few foods are good, natural sources)
  • through supplements (although it comes in different forms and researchers aren’t always consistent in their advice about which form is best)
  • through sunshine or the ultraviolet rays from the sun to be more precise (but SPF 8 or greater, heavy cloud cover, skin color, aging, and even the angle of the sun in winter blocks vitamin D from being made in sufficient amounts)

So what is an over-50 year old adult to do?

First, choose foods that contain vitamin D or foods that are fortified with vitamin D: salmon, mackerel, tuna and sardines are good sources because fatty fish contain this fat-soluble vitamin. Mushrooms (they are being exposed to ultraviolet light to make them good sources), milk, some but not all yogurts (read the label), many breakfast cereals and orange juice contain vitamin D. A recent study found that half of vitamin D intake comes from milk so that is a good place to start.

Second, consider supplementation; you might be getting some in your multi-vitamin and most contain 400 IU (IU stands for international units, the measure used in supplements). Vitamin D comes in two forms–D2 and D3 and most, but not all, experts recommend the D3 form because early research showed that D3 is more effective at raising vitamin D blood levels than D2. However, some research shows that both forms are effective at improving blood levels.

Third, consider getting some sensible sun–10 to 15 minutes of sun exposure twice a week can improve vitamin D levels. This recommendations is controversial because UV rays from the sun or tanning beds are tied to the million of skin cancer diagnoses each year.

Which leads us back to that 40 ng/mL blood level–is that good or bad? According to the lab report 40 is a healthy level, but trending more toward the insufficient end of the range. A controversial article in an international osteoporosis journal suggests that older adults need 800 to 1000 IU of vitamin D each day to reach the maximal blood levels of vitamin D.

Next time you go to the doctor and have blood drawn, ask for a vitamin D level–in the meantime, increase your intake of vitamin D from foods and if you supplement, look at the supplement label to determine how much vitamin D your supplement provides.

For more information check out Dr. Michael Holick’s website http://www.vitamindhealth.org/ or his new book, The Vitamin D Solution.