Susan Merenstein, Pharmacist/Owner

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What you need to know about Vitamin D!

While John R. Lee, M.D. was a leading expert on hormones such as progesterone, he also wrote and lectured widely on other substances that are essential to our health. One of those substances is Vitamin D, a nutrient that plays just as many roles in our overall wellness as progesterone.

Did you know that about one third of all Americans have low Vitamin D levels? Did you know that Vitamin D does much more than “build strong bones”? In recent years, medical research has revealed that having or not having a healthy Vitamin D level could make the difference in our having or not having a healthy life. Based on the latest research, people who have healthy Vitamin D levels may gain all of these benefits:

  • A reduced risk of osteoporosis, osteopenia, and bone fractures
  • Greater resistance to colds, flus, and COVID-19, and an improved ability to recover from these diseases
  • A lower risk of losing muscle mass, which can reduce one’s risk of falling
  • Fewer cases of cardiovascular disease, heart attacks, and strokes
  • Lower risks of death from cancer of the colon, pancreas, prostate gland, and other forms of cancer
  • A reduced risk of autoimmune diseases such as arthritis, multiple sclerosis, and diabetes
  • A lower risk of cognitive decline

More Than a Vitamin

Why is Vitamin D able to keep us well in so many ways? The key reason is that Vitamin D is more than a vitamin. Like progesterone, Vitamin D circulates in the blood and binds to cell receptors all over our bodies. As a result, it plays many beneficial roles in the healthy functioning of our organs and tissues. Dr. Lee knew this when he wrote, “If Vitamin D were discovered today, it probably would have been called an essential hormone.”

Just as our bodies produce their own progesterone, our bodies also produce their own Vitamin D. When our skin is exposed to ultraviolet rays from the sun, it produces Vitamin D. According to Dr. Lee, it takes only 20 minutes of exposing most of one’s body to the sun to get all of the Vitamin D we need for the day. Sadly, our modern lifestyles make it very hard for most of us to get our Vitamin D from sunlight. Our lives are largely lived indoors with our skin fully clothed, and we all get less sunshine in the fall and winter months, especially in the higher latitudes. This causes Vitamin D levels to drop, which is one reason why cold and flu rates rise during the colder seasons.

In addition, some groups of people have a harder time keeping their Vitamin D at healthy levels. As we age, our skin becomes less able to generate Vitamin D, so the elderly are more prone to deficiencies. In addition, people of color generate less Vitamin D because they have higher levels of melanin in their skin, as melanin partially blocks ultraviolet rays from entering the skin. Members of these groups may need to do more than other people to maintain healthy Vitamin D levels.

How to Maintain a Healthy Vitamin D Level

Fortunately, optimizing your Vitamin D level is not that hard, and the benefits you get from doing so are great! Here is what Dr. Lee advised, and it is what we advise too.

First, test your Vitamin D level regularly to know if you are deficient. Measuring your Vitamin D level is easy to do with a simple blood test. According to ZRT Laboratory, the laboratory we use for all of our hormone testing, people whose Vitamin D blood levels are less than 32 nanograms per milliliter (ng/ml) are probably deficient. Some experts recommend that levels be greater than 50 ng/ml for optimal health.

If you want to measure your Vitamin D levels but don’t know how, we can help! We offer ZRT Laboratory’s substitute our link to Vitamin D test on at home testing. Our test lets you measure your Vitamin D levels in the privacy of your home. The test contains a simple device that pricks the tip of your finger, then you put a few drops of blood on a card and mail it to ZRT Laboratory. Soon after, we will receive the test results in the mail. It’s that easy! The test monitors the blood levels of both the natural form of Vitamin D (D3) and D2, the form used in many supplements.

Second, spend short periods of time outdoors with full-skin exposure to the sun without sunscreen. As we said earlier, Dr. Lee stated that exposing most of one’s body to the sun for 20 minutes can produce all the Vitamin D we need for the day. To get that Vitamin D, do not use sunscreen. It is best to expose one’s skin between the hours of 10:00AM and 3:00PM. Sunbathing is not as effective at earlier or later hours because the sun’s rays must pass through a much thicker layer of the Earth’s atmosphere. This blocks much of the ultraviolet radiation that our skin needs to generate Vitamin D.

Third, take a Vitamin D3 supplement when needed to maintain optimal levels. Our modern lifestyles prevent many of us from getting adequate Vitamin D from sunlight or the foods we eat, so taking a Vitamin D3 supplement is strongly recommended. If you take a supplement, Dr. Lee suggests taking Vitamin D3 rather than D2. Vitamin D3 is the same form of Vitamin D that your skin produces when exposed to the sun.

Susan M. recommends multiplying your body weight by 45iu to get the daily iu of Vitamin D3 per day.

Your Vitamin D levels 25 (OH) D levels should be between 50-80ng/ml for optimal health. Test your levels in the fall and then again in the spring for best results.

If you are looking for a good place to buy Vitamin D3, try our Vitamin D3 5000iu capsules available on

If you follow these simple guidelines, you can easily maintain a healthy Vitamin D level for the rest of your life. More importantly, you will gain the significant health benefits and health protection that comes from doing so.


Gibbons, J.B., Norton, E.C., McCullough, J.S. et al. Association between vitamin D supplementation and COVID-19 infection and mortality. Sci Rep 12, 19397 (2022)

Holick MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr. 2004 Dec;80(6 Suppl):1678S-88S. doi: 10.1093/ajcn/80.6.1678S. PMID: 15585788

John R. Lee, M.D., What Your Doctor May Not Tell You About Menopause (New York, Warner Books, 2004 Revised edition)

Zittermann A. Vitamin D in preventive medicine: are we ignoring the evidence? Br J Nutr. 2003 May;89(5):552-72. doi: 10.1079/BJN2003837. PMID: 12720576

ZRT Laboratory. Patient Handout on Vitamin D and Vitamin D Testing.