The Importance of Vitamin D

Say goodbye to feeling blue this winter and get that sunny, summer feeling all season long. In addition to the vitamin D already found in the Essentials, this vitamin D supplement is available on its own and will help you maintain good health through the cold winter months!

Because our bodies use sunlight to make vitamin D, studies have shown that people in North America are extremely vitamin D deficient during the winter months. The problem is widespread and increasing, with potentially severe repercussions for overall health and bone-fracture rates.

USANA’s vitamin D supplement is formulated with a high level of vitamin D to ensure you get the vitamin D you need throughout the winter months in one tablet.

Be sure to bundle up this winter by visiting the USANA shopping cart and getting your extra dose of vitamin D!

Learn more from the USANA product catalogue:

Below are some articles published by USANA’s founder, Dr. Myron Wentz, on the importance of Vitamin D.

The Sun-Deficient Zone by Dr. Myron Wentz

In a recent post on vitamin D I referred to the “sun deficient zones” of the earth, which are the areas farther from the equator in which people do not get enough sun during winter months to produce the needed amounts of vitamin D from their skin. I may have confused some of you when I defined the “sun deficient zone” as being outside the latitudes of 37 degrees from the equator. Let me try and explain it better.

Visualize a line running east and west across the U.S. roughly from San Francisco to Las Vegas, St Louis and on to Washington DC. If you live north of this line, in cities such as Chicago, Toronto and New York, you are in the “sun deficient zone” and are at risk for all the vitamin D-preventable diseases I mentioned in a previous blog.

In Asia this line runs just north of Tokyo and Seoul, so Shanghai, Hong Kong, Taipei, Kuala Lumpur and Singapore all have healthy sun all year round. In the southern hemisphere, visualize a line running through Melbourne and Auckland. All the areas north of this line are in what we might call the “sun-sufficient” zone. Therefore most of New Zealand is in the sun deficient zone whereas Australia is not.

Virtually all of Europe is sun deficient in winter. Even sunny Italy and Greece are located where there is not enough sun in the winter months to produce adequate vitamin D. In contrast, virtually all of South America and all of Africa are in the sun-safe zone all year.

Proper sun exposure is so important. My guideline is approximately 20 minutes in midday sun most days of the week when you are in a sun-sufficient zone. For more information on sun exposures, see the Safe Sun Tables in Dr. Michael Holick’s book, The UV Advantage. He also discusses the effects of other factors, such as skin type, time of day, etc.

Although the consequences of vitamin D deficiency are extensive, it’s hard to know if you are deficient. It’s been said that if you press on your sternum (breastbone) and it hurts, you may be suffering from a vitamin D deficiency, but otherwise you need laboratory testing to determine what your blood levels are. Becoming deficient in vitamin D happens slowly, and recovery comes slowly, which is another reason why daily supplementation is important, especially if you live in a “sun deficient” zone.

As I promised, here are more study results confirming that sun deprivation increases the risk of degenerative disease.

1. Multiple sclerosis is about five times more likely to affect you if you live in North America or Europe compared with the tropics.

2. Diabetes is very rare in equatorial regions, while Finland has the world’s highest incidence.

3. The cancer death rate is 150 percent greater in people living in high latitudes than in the tropics.

Vitamin D by Dr Myron Wentz

Vitamin D is being rediscovered. Mainstream views that have dominated nutritional science over the past several decades focus on vitamin D’s role in calcium metabolism and bone health. The recommended vitamin D intakes for adults have been from 200 to 600 IU per day. And reference values for blood levels of circulating vitamin D (indicating adequate vitamin D status) stand at 30-40 ng/ml.  But all of this is being revised.

Recent research shows that our conventional wisdom concerning vitamin D is far too narrow and limiting. We now know that, in addition to maintaining bone health, sound vitamin D nutrition plays important roles in supporting cardiovascular health, preventing some cancers, promoting robust and balanced immune function, maintaining sound muscle function, normalizing glucose levels, and more. In my opinion the scientific evidence clearly indicates that the optimal range for circulating vitamin D is 40-80 ng/ml, far higher than the current reference range. Moreover, it is becoming clear that vitamin D intakes in the neighborhood of 2,000 IU per day (and up to 4,000-5,000 IU per day during winter months) are needed to maintain these concentrations.

Unfortunately, this news comes late for many of us. The conventional wisdom has not served us well. Very high percentages of people around the world, particularly those living in temperate climates, are chronically deficient for vitamin D, and their health has suffered because of it. Up to 40% of the U.S. population is vitamin D deficient, and certain groups, such as the elderly, have even higher rates. In the weeks ahead, I will be sharing with you my thoughts on what each of us needs to do to get the amounts of vitamin D we truly need. Stay tuned.


In my last message on vitamin D I talked about how frequent deficiency of this important nutrient is among all age groups. We know that more than 1 billion people worldwide and 30-to-40% of the adult US population have inadequate levels of vitamin D. In addition, new evidence indicates that optimal levels are significantly higher than previously believed.

Vitamin D is unique among essential nutrients in that we normally obtain most of what we need from exposure to the sun, rather than from our diet. Today we have various reasons for not being out in the sun as much as previous generations did. We have an exaggerated fear of sunburn and skin cancer, and too many excuses—from big-screen televisions to computer games—to stay inside.

That means dietary sources and supplementation need to be resorted to to carry the day. Natural dietary sources of vitamin D include oily fish (such as salmon, tuna, and mackerel) and fish oils. Small amounts are found in beef liver, cheese, and eggs. Fortified foods (dairy, breakfast cereals, fruit juices and meal replacements) provide most of the vitamin D in the Western diet.

However, we obtain very little of our vitamin D from food, even from a healthy, well-balanced diet. The average American obtains only about 200 IU of vitamin D per day from food. This amount is only about 30-50% of the adult RDA. And given what we know now, it is only about 5-10% of the amount of vitamin D we need daily to maintain optimal health. Supplemental vitamin D, therefore, is critical to long-term good health today. The only option, then, if we don’t get proper sun exposure, is supplementation.

How much supplemental vitamin D is required to make up for these shortfalls? On average about 2,000 IU of vitamin D in the summer and higher levels during the winter. We know this from a wide range of published clinical studies, as well as from clinical research conducted at USANA Health Sciences. It takes about 100 IU of supplemental vitamin D per day to increase blood concentrations of vitamin D by ~1 ng/ml. As a rule of thumb, advanced supplemental doses of vitamin D, to the tune of 2000-4000 IU/day, depending on season and lifestyle, are required to reverse vitamin D deficiency in most people.

I urge all of you to adopt a program of advanced vitamin D supplementation, one that supplies at least 2,000 IU of vitamin D per day, and preferably more during the winter months. As part of your overall strategy for maintaining optimal vitamin D status, you also need to complement this program with prudent sun exposure and regular vitamin D blood tests. I discuss both of these topics in detail in the future.

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