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Vitamin D facts – why is Vitamin D the sunshine vitamin?

We’ve all heard about Vitamin D – but what is so special about it?

Key Fact No. 1: Vitamin D is a key hormone that is critically important for the development, growth, and maintenance of a healthy body from conception through pregnancy, birth, childhood, adulthood until death.

Key Fact No. 2: Research over recent years shows that Vitamin D deficiency is a major factor in the presence of automimmune diseases, at least 17 types of cancer, chronic pain, heart disease, stroke, hypertension, as well as diabetes, depression, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more.

So you can see that Vitamin D is exceptionally important for our long-term health and well-being.

To give you an idea here is a list of the important functions that is Vitamin D involved in.

Vitamin D:

• regulates calcium and phosphorus levels in the blood and helps absorb these minerals from food in the intestines (1).
• is essential of efficient utilisation of calcium by the body (1).
  • Vitamin D regulates the secretion of the hormone parathyroid from the parathyroid gland when calcium levels get too low. Increases in parathyroid production increase Vitamin D production in the kidney. This in turn increases the intestinal absorption of calcium from the diet and calcium re-absorption by the kidneys, as well as mobilising calcium from bone when normal calcium levels cannot be provided by the diet (2).
• manages the re-absorption of calcium in the kidneys, which in turn facilitates the normal mineralization of the bones (1).
• is vital for bone growth and is essential in the development of a complete, well-formed and strong skeleton. Insufficient Vitamin D can lead to thin, brittle or misshapen bones (rickets in children and osteomalacia in adults). In association with calcium Vitamin D helps protect the elderly from osteoporosis (3, 4).
• invigorates the immune system (5,6).
  • Vitamin D is important for the immune system by promoting immunosuppression, anti-tumour activity and phagocytosis. Phagocytosis is involved in the acquisition of nutrients for some cells, and in the immune system is a major mechanism used to remove pathogens and cell debris. Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytosed.
• is essential to normal cell growth and function, making it a key factor in maintaining hormonal balance and a healthy immune system.
• is involved in insulin secretion (7).
• helps maintain healthy blood vessels and heart muscle cells to prevent heart disease, hardening of the arteries and hypertension (8-10).

So you  see now why it is so important that we understand all the Vitamin D facts. The benefits of Vitamin D are important for much aspects of your well being.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin. It is a hormone that targets over 2000 genes (equating to about 10%) in the human body. The skin provides the greatest natural production of Vitamin D when the skin is exposed to ultraviolet rays from sunlight. Vitamin D is also naturally present in a small number of foods, is sometimes added to some foods, and is available as a dietary supplement.

The term “Vitamin D” covers several forms of this vitamin, including two which are important in humans. Vitamin D₃ (cholecalciferol) can be synthesized by humans in the skin upon exposure to ultraviolet-B (UVB) radiation from sunlight, or can be obtained from the diet. Plants synthesize ergosterol, which is converted to vitamin D₂ (ergocalciferol) by ultraviolet light. Vitamin D₂ is less active in birds than vitamin D₃ and may also be less active in humans. When exposure to UVB radiation is insufficient for adequate production of vitamin D₃ in the skin, Vitamin D supplements are essential for maintaining good health (11).

Vitamin D itself is biologically inactive, and must be metabolized into its biologically active forms. After it is consumed in the diet or synthesized in the skin, Vitamin D is transported to the liver. In the liver, Vitamin D3 undergoes a chemical reaction with the addition of a hydroxyl (hydroxylated) to form 25-hydroxyvitamin D [25(OH)D]. This is also known as calcodiol and is the major form of Vitamin D. Increased exposure to sunlight or increased dietary intake of Vitamin D increases serum levels of 25(OH)D – this is why concentrations of the serum 25(OH)D are such a useful indicator of Vitamin D nutritional status. In the kidney, a second hydroxylation of 25(OH)D forms 1alpha,25-dihydroxyvitamin D [1,25(OH)₂D]. This is also known as calcitriol and is the most potent form of Vitamin D. Most of the physiological effects of Vitamin D in the body are related to the activity of 1,25(OH)₂D (12).  Calcitriol has powerful anti-cancer properties.

Do we get enough Vitamin D?

The simple answer is NO. Dr. M Holick, Professor of medicine, physiology, and biophysics, and Director of the General Clinical Research Center at Boston University School of Medicine and Director of the Bone Healthcare Clinic at Boston Medical Center, has been estimated that 1 billion people world-wide have insufficient levels of Vitamin D or are Vitamin D deficient (13). Vitamin D is only stored in your blood for a few weeks and in your fat for just a few months so regular Vitamin D production is essential. Vitamin D production fluctuates with the seasons. Low winter/springtime Vitamin D levels has been linked with the development of a number of autoimmune diseases, such as autism and type 1 diabetes, as well as schizophrenia and cancer.

Am I likely to be Vitamin D deficient?

Actual percentages vary between research studies. However, there is a general consensus that a large proportion of American children, teenagers and adults have Vitamin D deficiency and results from other countries show similar patterns of deficiency.

• A recent study by researchers at Albert Einstein College of Medicine of Yeshiva University of over 6,000 US children found that 70% had low levels of Vitamin D (14).
• Up to 50% of American adults have Vitamin D deficiency and this may be higher in older adults. A study in China found that 94% of over 3000 people aged 50-70 years had less than acceptable Vitamin D levels (69% were Vitamin D deficient and 24% were Vitamin D insufficient;15).
• People in higher latitudes (Alaska, Canada and northern Europe) where the sun is too weak to power Vitamin D production.
• Deficiency is higher in winter when people spend less time outside and there are fewer hours of daylight. For example, in Boston there is insufficient sunlight on average for Vitamin D production from November through to February.
• People with dark skins take more sun to synthesise Vitamin D.
• Older people are more at risk because they tend to get less sun exposure and the skins production of Vitamin D decreases with age.  Their kidneys also have a reduced ability for the kidney to convert Vitamin D into its active hormone form. At least half the cases of hip fractures in older Americans are thought to be related to Vitamin D deficiency.
• Obese people are less efficient at producing Vitamin D in response to sunlight. Vitamin D gets trapped in fat cells.

Is Vitamin D deficiency a problem?

The over riding answer is YES. Vitamin D is critical to our health. The symptoms of Vitamin D deficiency are often subtle. Low Vitamin D levels in the blood can lead to many diseases and health issues (4), including.

• Rickets
• Osteomalacia
• Osteoporosis
• Muscle weakness and pain
• Cardiovascular disease and related health issues
• Multiple sclerosis
• Cancer
• Tuberculosis
• Diabetes
• Susceptibility to cardiovascular disease and diabetes.

What is an adequate intake of Vitamin D?

In 1997 the Food and Nutrition Board of the Institute of Medicine produced a table to provide adequate intake (AI) levels required assuming that no Vitamin D is being synthesized in the skin through exposure to sunlight.

Many experts now feel these levels are too low and should be increased (16-18). Recently the American Academy of Pediatrics increased their Vitamin D intake recommendation to 400 IU/day for all infants, children, and adolescents (19). Dr M. Holick believes the current recommended Adequate Intakes for Vitamin D need to be increased to 800 — 1000 IU Vitamin D3 per day (12) and the Linus Pauling Institute Micronutrient Information Center, Oregon State University, have recommended 2,000 IU (50 mcg) of Vitamin D per day for older adults because of their reduced capacity to produce Vitamin D via sun exposure to the skin (20).

The recommended Vitamin D dosage varies widely depending on who you talk to or which research you’ve read. Through our research we found this to be true and also extremely frustrating. We felt the recommended dosage levels were generally too low and not current with the cutting edge research coming out.

To find out how much Vitamin D you need to take please check out our Vitamin D Dosage page. Table

Vitamin D Facts – How can I get more Vitamin D?

• Take daily Vitamin D supplements (at least 1000IU per day)
• Sun. Have 5 to 15 minutes of exposure (for Caucasian skinned people) to the sun at least 2 or 3 times per week in the spring, summer and autumn between the hours of 10am and 3pm. People with darker skins will need to spend longer outside. Expose your arms and legs, but always put sun cream on your face, neck and upper torso.
• Food. The required daily intake of Vitamin D cannot be acquired through food. Oily fish such as salmon, tuna and mackerel provide the best sources of Vitamin D.

Thanks for taking time to read up on Vitamin D facts. So you can now see why Vitamin D is called the “sunshine vitamin”. Throughout our lives Vitamin D has a major influence on key biological functions that are vital for our health and well-being. Many major diseases and illnesses are linked to low levels of Vitamin D.

The most important thing you can do is make sure you are getting an adequate intake of Vitamin D. Supplements and exposure to the sun are the best combintion for achieving this. Supplements become increasingly important for getting enough Vitamin D as you get older.

Vitamin D – the “sunshine vitamin” is your ticket to long-term health and well being.

Make sure you check out our more detailed information on Vitamin D facts below:

Vitamin D facts and heart disease

Vitamin D facts related to moods

Vitamin D facts in children

Vitamin D facts every man should know

Vitamin D facts for women over 50

Vitamin D facts and menopause

You may also be interested in learning more on sources of Vitamin D and Vitamin D Supplements.

Here’s to your long-term health!

Claire

Articles cited:

1. Holick MF. Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr. 2004;79(3):362-371.

2.  DeLuca HF. Overview of general physiologic features and functions of vitamin D. Am J Clin Nutr. 2004;80(6 Suppl):1689S-1696S.

3.  Wharton B, Bishop N. Rickets. Lancet. 2003;362(9393):1389-1400.

4. http://www.vitamindhealth.org Dr M Holick website

5.  Hayes CE, Nashold FE, Spach KM, Pedersen LB. The immunological functions of the vitamin D endocrine system. Cell Mol Biol. 2003;49(2):277-300.

6.  Griffin MD, Xing N, Kumar R. Vitamin D and its analogs as regulators of immune activation and antigen presentation. Annu Rev Nutr. 2003;23:117-145.

7.  Borissova AM, Tankova T, Kirilov G, Dakovska L, Kovacheva R. The effect of vitamin D3 on insulin secretion and peripheral insulin sensitivity in type 2 diabetic patients. Int J Clin Pract. 2003;57(4):258-261.

8.  Zittermann A. Vitamin D in preventive medicine: are we ignoring the evidence? Br J Nutr. 2003;89(5):552-572.

9. Massachusetts General Hospital (2009, September 22). Insufficient Levels Of Vitamin D Puts Elderly At Increased Risk Of Dying From Heart Disease. ScienceDaily. Retrieved November 1, 2009, from http://www.sciencedaily.com­ /releases/2009/09/090921134654.htm

10. American Heart Association (2008, January 8). Lack Of Vitamin D May Increase Heart Disease Risk. ScienceDaily. Retrieved November 1, 2009, from http://www.sciencedaily.com­ /releases/2008/01/080107181600.htm

11. Armas LA, Hollis BW, Heaney RP. Vitamin D₂ is much less effective than vitamin D₃ in humans. J Clin Endocrinol Metab. 2004;89(11):5387-5391.

12. Holick MF. Vitamin D: A millenium perspective. J Cell Biochem. 2003;88(2):296-307.

13. 24. Boston University (2007, July 19). Vitamin D Deficiency: Common And Problematic Yet Preventable. ScienceDaily. Retrieved November. http://www.sciencedaily.com/releases/2007/07/070719011417.htm

14. Michal L. Melamed, Juhi Kumar, Paul Muntner, Frederick J. Kaskel, and Susan M. Hailpern. Prevalence and Associations of 25-Hydroxyvitamin D Deficiency in Children and Adolescents in the United States: Results from NHANES 2001-2004. Pediatrics, August 3, 2009

15. Lu L, Pan AN, Hu FB et al. Plasma 25-hydroxyvitamin D Concentration and Metabolic Syndrome among Middle-aged and Elderly Chinese. Diabetes Care 2009.

16.  Heaney RP. Vitamin D: how much do we need, and how much is too much? Osteoporos Int. 2000;11(7):553-555.

17.  Hollis BW. Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D. J Nutr. 2005;135(2):317-322.

18.  Vieth R. Why the optimal requirement for Vitamin D3 is probably much higher than what is officially recommended for adults. J Steroid Biochem Mol Biol. 2004;89-90(1-5):575-579.

19.  Wagner CL, Greer FR, and the Section on Breastfeeding and Committee on Nutrition. Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. American Academy of Pediatrics. 2008;122(5):1142-1152.  Available at: http://www.aap.org/new/VitaminDreport.pdf .

20. http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/