Update: Link between vitamin D and dementia risk confirmed: Vitamin D deficiency is associated with a substantially increased risk of dementia and Alzheimer’s disease in older people, according to the most robust study of its kind ever conducted. (exeter.ac.uk)
Do you know how to optimize your vitamin D levels for every season?
A growing body of knowledge shows that, at optimized levels, vitamin D functions as a hormone rather than a vitamin, with numerous notable effects on the body.
These effects include support for:
• Healthy immunity
• Healthy mood
• Targeted support for over 2000 genes
• Healthy bone formation
• Healthy glucose metabolism
• Musculoskeletal comfort
• Heart health
• Healthy skin
Many health experts consider the benefits of vitamin D to be one of the most important health discoveries of the past 100 years.
In this video newsletter, I’ll share new research on vitamin D deficiency—which affects 87% of Americans—and walk you through how to safely increase your levels.
History of Vitamin D Deficiency
Vitamin D deficiency causing devastating bone-softening effects was reported as far back as the 1600’s. Originally treated with cod liver oil in the 1800’s, it wasn’t until the 1930’s that vitamin D deficiency was discovered as the cause.
Though called “vitamin D,” it is not really a vitamin, but a hormone. In fact, at optimized levels in the blood, the active form—known as calcitriol—is now understood as the most potent secosteroid hormone in the human body. At optimal levels its effects may extend far beyond bone support, showing responsibility for many health-promoting processes in the body.
Vitamin D “Overflow”
About 10 years ago, researchers discovered that people who live in climates where natural sun exposure was the greatest experienced greater longevity. In northern climates, studies show up to 61% of Americans are vitamin D deficient, going up to 87% in the winter months (1)(2).
For the past 80 years it was believed that vitamin D was only important to the body for regulating calcium and protecting the bones. At levels below 50ng/ml, this is vitamin D’s main role.
However, new research reported by the Vitamin D Council has shown that higher levels of vitamin D may have a much greater role to play. For example, when vitamin D3 levels are between 50-80 ng/ml the excess calcitriol (secosteroid hormone form of vitamin D) heads towards the cells—not the bones—where it then targets over 2,000 genes (about 10% of the human genome) in the human body.
It is this “overflow” of calcitriol that has created such a worldwide stir about the pervasive role of optimized vitamin D. At lower levels of sun exposure and vitamin D, this overflow simply doesn’t happen. The role of excess calcitriol in the cells—and the great importance of these findings – is only now being understood.
No Sun=No Fun
Fifty thousand years ago, humans lived predominately in climates around the equator. Clothing was minimal and sun exposure was constant. As we migrated north, we endured sunless winters, wore more clothes and adapted to living indoors – away from the sun.
Today, we live, sleep, eat and drive indoors away from the vitamin D-rich UVB sun rays. In latitudes north of Atlanta (33°N), the UVB (vitamin D making sun rays) simply do not exist from November through March, making these months an emotional endurance event for many.
Seasonal mood disturbances and feeling low in the winter months is often found to have a connection with low serotonin levels, which may be related to lack of sunlight (2).
It is the UVB rays that convert the cholesterol (7-dehydrocholesterol) on the skin into D3 (cholecalciferol). According to the US News Report, UVB rays are only available when the UV Index is at 3 or above, which doesn’t happen in the winter for most of America. You can check the UV Index in your area.
D3 versus D2
The D3 form of vitamin D has been shown to have the highest absorptive affinity and less toxicity in the human body compared to the more popular vitamin D2 (ergocalciferol) (3). For this reason, vitamin D3 will store longer in the fats cells and help us endure a long, UVB-deficient winter.
Vitamin D2, which absorbs into the body 70% less effectively than vitamin D3 (4), was long thought to be the most active source of vitamin D supplementation. It is still used to fortify foods such as milk and orange juice and is the main pharmaceutical form of vitamin D support, though many pharmacies are now switching to vitamin D3 supplementation. Vitamin D3 is primarily derived from the sun, but is also found in cod liver oil and some fatty fish.
Native people commonly got their vitamin D3 in the winter by eating organ meats, which are generally rich in the fat soluble vitamins including vitamin D.
How to Get Vitamin D3 from the Sun
During the summer months, the UVB rays are the strongest between 10am—2pm. For most people, 10-15 minutes of direct sunlight on unprotected skin during these hours will be enough to manufacture about 10,000—20,000 IUs of vitamin D3. Get just enough sun to turn your skin slightly pink. Darker-skinned people will have to get more sun to optimize their vitamin D levels.
It takes about an hour for the cholesterol on your skin to convert to D3 and then to be absorbed. So, if you work out in the sun and then take a shower, you might be washing off all that precious vitamin D you just manufactured on your skin.
If you can, wait at least an hour before rinsing off. Many animals get their vitamin D by licking their fur after being in the sun—the oil on their skin and fur has combined with the UVB rays to make vitamin D3.
How Your Body Uses Vitamin D3
From the skin, the vitamin D3 (cholecalciferol) heads to the liver, where it is converted to calcidiol (25 hydroxyvitamin D). This is the form that circulates in the blood and is most accurately measured on a blood test.
From here, the calcidiol heads to the kidneys where it is converted to calcitriol (1,25-dihydroxyvitamin D), the most active form of vitamin D, which circulates to every tissue in the body.
Vitamin D Supports Immunity
Vitamin D expert Dr. John Cannell developed a theory that some immune issues are seasonal due to seasonal variations in sunlight, which cause fluctuations in vitamin D levels (3)(4). Vitamin D activates genes that support an immune response to foreign entities in the body (5).
Vitamin D has also been shown to support healthy respiratory immunity (6) (7).
Pro-inflammatory cytokines may be responsible for many lasting health issues. Vitamin D3 down-regulates cytokine activity and supports a healthy inflammatory response (7).
Vitamin D Toxicity: Fiction or Fact?
Current understanding has it that the physiological requirement for vitamin D may be as high as 4000 IU/day for adults. Although the Food and Nutrition Board established the tolerable upper intake level (UL) at 2000 IU/day for adults, newer research demonstrates that this amount is very conservative, and it appears unlikely that toxicity would occur in healthy people with doses less than 10,000 IU/day (8).
For adolescents, 2000 IU daily for a year has proven to be safe and efficacious (9).
With many articles discussing that individual sensitivity issues may exist, it’s important to be aware that vitamin D toxicity is rare. One study showed that 4,000 IUs per day for several years was completely safe and only after taking 40,000 IUs per day for several years is there a risk of developing toxicity symptoms (5).
That being said, as I review the research, I am not so convinced that we can be casual about the intake of high dosages of vitamin D supplements. Ideally, I think we should all do our very best to optimize our vitamin D levels in the summer when the UVB rays are available. There is no vitamin D toxicity from the sun because UVA rays break down the excess vitamin D.
Vitamin D is stored in the fat, so we do carry much of it into the winter months if we optimize the summer’s UVB rays. Unfortunately, most of us work indoors during midday summer hours when the UVB rays are at their peak.
For the past 25 years, sunscreens have only blocked out the skin-protecting UVB rays, but not the UVA rays. It was mistakenly thought that the UVB rays were the rays that potentially caused abnormal cell division in the skin cells, so sunscreens were designed with SPF factors that reflect the effectiveness of blocking only UVB rays. As it turns out, UVA rays are more abundant and penetrate deeper into the skin, making them more harmful than the UVB rays.
Additionally, twenty years ago, SPF ratings were only at 10, but today they have risen up to 100 in the effort to make the sunscreens more protective against abnormal cell growth. Sadly, all this time sunscreens have been blocking the good, protective UVB rays while letting in the harmful UVA rays.
Take a Vitamin D Test
While it is difficult to become toxic with vitamin D, experts believe that it is ideal to keep the levels at the higher end of normal, which is between 50-80ng/ml. To maintain these optimal levels it is best to take a vitamin D test in the spring and fall.
If getting a blood test presents a problem because of the inconvenience of getting a doctor’s appointment, we offer an accurate Vitamin D Test Kit that you can do at home. This test is inexpensive, safe, simple, accurate and approved by the Vitamin D Council.
How to Optimize Your Vitamin D Levels and Prevent Deficiency
Summer Sun Exposure
Regularly receive midday sun exposure between 10am – 2pm in the late spring, summer, and early fall, exposing as much of the skin as possible for 10-15 minutes if your are fair skinned. Longer if you are dark skinned. Remember, you have had enough when the skin shows the first sign of a pinkish change.
Supplementation: Depending on your sun exposure, I suggest minimal Vitamin D3 supplementation in the summer—perhaps a dose of 1,000-2,000 IUs per day.
Test Your Levels: Test your vitamin D levels to ensure you have optimized summer sun exposure.
Supplements: Take 4,000 IUs of Vitamin D3 per day for three months, and then take a 25-hydroxyvitamin D test.
The goal is to get your vitamin D levels between 50-80ng/ml and keep them there. Testing is the only way to know for sure that you are maintaining these levels. Test yourself in the fall when the levels are the highest and in March when they are the lowest. With those two numbers, everyone can safely calculate their vitamin D supplement needs.
Children: Take 2,000 IUs of Vitamin D3 per day during the winter.
Source: Vitamin D Council
1. J Clin Endocrinol Metab. 2002 Nov; 87(11): 4952-6.; 2. AM J Clin Nutr. 2007 Mar; 85(3): 860-8; 3. Virol J. 2008; 529; 4. Epidemiol Infect. 2006 Dec; 134(6): 1129-40; 5. Science News. 2006 Nov 11: 312-3; 6. J Immunol. 2003 Dec 15; 171(12): 6690-6; 7. Partonen T. Vitamin D and Serotonin in the Winter, Med Hypotheses. 1998 Sept;51(3):267-8; 8. Tsiaras WG, Weinstock MA. Factors infl uencing vitamin d status. Acta DermVenereol. 2011 Mar;91(2):115-24. [PMID: 21384086]; 9. Cannell JJ, Hollis BW. Use of vitamin D in clinical practice. Altern Med Rev.2008 Mar 13 [PMID: 18377099]; 10. Armas LA, Hollis BW, Heaney RP. Vitamin D2 is much less effective than Vitamin D3 in humans. J Clin Endrinol Metab. 2004;89(11)5387-91; 11. Trang HM, Cole DE, Rubin LA, et al. Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. Am J Clin Nutr. 1998 Oct;68(4):854-8; 12. Heaney RP, Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr.2003. Jan 77;(1):204-10.
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Ed: Bryonie Wise
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