The Effect of Sunshine and Winter on Vitamin D
Today, many people are aware of the importance of vitamin D for optimal health. Vitamin D, a fat-soluble vitamin, is actually a hormone. So why is vitamin D crucial for your health? Let’s take a look at some of its many benefits. 

Benefits of Vitamin D

Research now shows that vitamin D has beneficial influences on:  

  • Flu and colds
  • Osteoporosis
  • Depression 
  • Diabetes 
  • Muscle strength 
  • Gum and dental health 
  • Prostate cancer 
  • Colon cancer 
  • Lung cancer 
  • Breast cancer 
  • Lymphoma 
  • PMS 
  • Kidney disease 
  • Heart disease 
  • Multiple sclerosis 
  • Arthritis 
  • Pain 
  • Preeclampsia 
  • Anaphylaxis 
  • Obesity 

Vitamin D is essential for a healthy immune system. It boosts the immune system and enhances the body’s ability to kill bacteria or viruses. Research shows that sunlight and vitamin D do lessen the rate of major internal cancers. There is even a correlation between low vitamin D levels and hearing loss, insomnia, macular degeneration, eczema, psoriasis, kidney disease, pre-eclampsia, fertility, near-sightedness, epilepsy and anemia. (1)

Sources of Vitamin D

How do you get vitamin D? 

  • Sunlight exposure is the most natural way to get adequate vitamin D, however a large area of skin must be exposed, not just the face and arms (while NOT wearing sunscreen, which blocks vitamin D production) 
  • Some fish (such as cod liver oil, wild-caught salmon, mackerel, and tuna fish)
  • Foods (such as eggs) and Foods Fortified with Vitamin D
  • Vitamin D3 Supplements (not D2, which is considered less effective, and D2 is not produced naturally in the body) 

Sunlight and Vitamin D

You many have heard vitamin D referred to as “the sunshine vitamin,” and for a good reason! Vitamin D production is stimulated by sunlight. Sunlight gives off three types of ultraviolet light, UVA, UVB and UVC, however only UVB light can penetrate and stimulate your skin to produce vitamin D. Sunshine exposure has been shown to be good for your health.

Many ancient people were sunbathers – they knew many years ago about the beneficial effects of the sun. The Egyptians, Babylonians and Assyrians had sun gardens and gave the sun the status of a god. Hippocrates, the Greek physician known as the “father of medicine,” recommended sunbathing for health and had his own large solarium. (1)   

In the early 19th century, scientists experimented with sunlight as a remedy. Many doctors used heliotherapy with success. In 1877, two scientists discovered that sunlight was bactericidal. It was shown that sunlight killed TB bacteria. When children with tuberculosis (TB) were exposed to sunlight, it hastened their recovery. One doctor went to the Swiss countryside to practice medicine, but he discovered that the people were seldom sick because they had adequate sunlight exposure. (1)

How does the vitamin D system work?  

  1. The skin contains cholesterol, and when UVB light contacts the skin, some of the cholesterol converts to vitamin D3. D3 also enters the blood through food or supplements. 
  2. D3 is transported to the liver where it is further converted to calcidiol. 
  3. Calcidiol is then changed to calcitriol in the kidneys and other tissues. 
  4. Calcitriol then binds to the vitamin D receptor of the various tissues, where it performs its remarkable functions in enhancing human health. It is important to understand that calcitriol is the ONLY form that produces benefits. The stored form of vitamin D has no effect until it is converted to calcitriol. 
  5. Calcitriol works in concert with the parathyroid hormone (PTH) to regulate calcium absorption and control serum calcium levels. PTH levels rise when vitamin D is insufficient, and cause loss of calcium from the bone. 

Why So Many People are Vitamin D Deficient Today

It has been estimated that over one billion people have either vitamin D insufficiency or deficiency. (3)

To get enough vitamin D, you need regular exposure to sunlight. There are many reasons that people don’t get enough sun to produce vitamin D:

  • Winter months
  • Living in high latitudes
  • Living inside homes
  • Working inside offices
  • When outside, people usually cover themselves with clothing and sunscreen 

By the way, did you know that sunscreens block up to 99% of vitamin D production by the skin? 

Low concentrations of vitamin D is a general challenge for most people during the winter, especially among people living in in high latitudes. Vitamin D varies through the year, and has its lowest point in spring. Many of the negative health effects during wintertime may therefore be related, in part, to this reduction in vitamin D. (2)

If you live in the north, then you definitely aren’t getting enough sunshine year-round. People with darker skin also tend to have low vitamin D levels. The elderly produce far less vitamin D in response to sunlight, plus they spend less time in the sun and consume less vitamins. 

The seasons influence UVB light, which as we know stimulates the skin to produce vitamin D. But if the sunlight is not sufficiently direct, or if it has been filtered extensively by the atmosphere, UVB will not be present in sunlight, and vitamin D will not be produced. Our planet rotates on its axis, but that axis is not parallel to the sun. It is tilted at a 23.5% angle, the tilt that causes the change in seasons. Earth tilts towards the sun during summer in the northern hemisphere (the sunlight is more direct and less filtered than in the winter) and away from the sun during the winter. The exact opposite is true for the southern hemisphere. (1)  

The sunlight does not always contain the quantity of UVB light necessary to produce vitamin D. UVB light is filtered by the atmosphere, and that filtration is much greater in winter than in summer. For instance, in Boston, there is insufficient UVB available to produce vitamin D from November through February. In Edmonton Alberta, Canada, the “vitamin D winter” extends from October through March. (1) 

Another factor is time of day. At dawn, the sunlight comes to Earth at an almost horizontal angle and passes through miles of filtering atmosphere. All UVB is filtered out, even on summer’s first day. At midday, however, the sun is directly overhead and passes through little atmosphere, so much more UVB reaches the Earth. (1)

Seasonal Affective Disorder (SAD)

You may be familiar with a condition called Seasonal Affective Disorder (SAD), when people experience depressed moods in the winter months when there is less sunshine.

Seasonal affective disorder is a form of depression that usually begins in the fall, continuing throughout the winter months. It affects up to 10% of the U.S. population. Symptoms include feeling sad or anxious, fatigue, concentration problems, irritability and feelings of guilt and hopelessness. Numerous studies have suggested the condition may be triggered by lack of sunlight. SAD is more common among people who live at high latitudes or areas with lots of clouds. (4)

Vitamin D also plays a part in the synthesis of both dopamine and serotonin, noting that past research has associated low levels of these neurotransmitters with depression. (4)

Test Your Vitamin D Level

Be sure to have a doctor check your vitamin D level so that he or she can recommend the correct dosage to get you to your optimal level. The best assessment of vitamin D is by a serum 25-hyroxyvitamin D (25-OH D) level. (3)

Order Your Vitamin D3 Supplements Today!

Are you ready to optimize your vitamin D level? Order Vitamin D3 today, or call 281-646-1659 and speak with one of our Certified Holistic Nutritionists and Vitamin Consultants. It will be our privilege to serve you!