The major role of vitamin D is to maintain normal blood levels of calcium and phosphorus and keep them in balance to support and maintain healthy bones.
Two new studies tested vitamin D at or above the Recommended Dietary Allowance (RDA) of 600 IU daily up to age 70 and 800 IU daily over age 70. Results show that vitamin D plays an important role in insulin sensitivity and artery stiffness. NutritionAction.com has published the findings in their May 23, 2018 newsletter.
An extreme and prolonged deficiency of vitamin D causes rickets, resulting in soft bones and bowed legs in children. Low levels of vitamin D are associated with increased loss of muscle strength and mass as we age, increased risk for cancers, lower immunity, high blood pressure, development of neurological disorders, and development of diabetes.
Vitamin D comes in two forms:
Vitamin D2 – ergocalciferol, and Vitamin D3 – cholecalciferol.
Vitamin D2 is produced by plants and mushrooms exposed to sunlight. Vitamin D3 is synthesized in the skin of humans and animals — earning the moniker “The Sunshine Vitamin.”
Global Deficiency of Vitamin D?
The VitaminCouncil.org reports that prior to the 20th-century humans obtained approximately 95% of vitamin D3 through sun/skin synthesis. Since the middle-late part of the 20th century, research shows that it could be as low as only 15-25%.
Health experts report that vitamin D deficiency is a “global health problem.” As reported in the International Journal of Health Sciences (January 2010), “Over a billion people worldwide are vitamin D deficient or insufficient”. A study published in the journal Food and Nutrition Bulletin (March 2013) examined the data and found that throughout Latin and Central America vitamin D deficiency may be a public health problem, despite the abundance of sunshine.
- Certain medical conditions including Crohn’s disease, cystic fibrosis, and celiac disease increase risk of vitamin D deficiency: these can affect the intestine’s ability to absorb vitamin D from foods.
- Obese and overweight people may have a more difficult time maintaining optimal limits of D; since vitamin D is a fat-soluble vitamin, subcutaneous fat may sequester the vitamin. A May 22, 2018 study concludes that higher levels of abdominal fat may predict vitamin D deficiency.
- Vegans may be at increased risk since they avoid the most bioavailable dietary sources of vitamin D3, including fish and fish oils, egg yolks, fortified milk, and liver. They need to be sure to eat fortified foods and/or take dietary supplements.
- Some medications can decrease the activity of vitamin D in the body including anticonvulsants, bile acid sequestrants, gastroesophageal reflux disease (GERD) medications, corticosteroids, and heparin.
- Seniors may be at high risk for deficiency, due both to the decrease in time in the sun/sun exposure, but also because a person over 70 produces about 30% less vitamin D than a younger person with the same sun exposure. As people age, they’re less able to convert vitamin D to its active form.
- Because of the awareness of potential dangers of skin cancer, many people use UVB-blocking sunscreen, blocking the skin’s ability to manufacture D3.
Vitamin D For Optimal Health
All vitamin D supplements are not equal in terms of how your body can use the vitamin. Research shows that vitamin D3 supplements are twice as effective as vitamin D2. But how much is enough? When does too much become dangerous? And is supplementation necessary or effective for everyone?
Vitamin D is a fat-soluble vitamin, which means it can dissolve in fats and oils and are absorbed with fats in the diet, and stored in the body’s fatty tissue (other fat-soluble vitamins are A, E, and K).
According to WebMD.com, “Guidelines from the Institute of Medicine increased the recommended dietary allowance (RDA) of vitamin D to 600 international units (IU) for everyone ages 1-70, and raised it to 800 IU for adults older than age 70 to optimize bone health.”
The safe upper limit was also raised to 4,000 IU.
How Much Is Too Much?
Studies show that people with the highest levels of vitamin D have more bone fractures, fall more frequently, get less sleep, and have a higher mortality rate compared to those with lower, but sufficient, levels. Signs of vitamin D toxicity include chronic constipation, nausea, confusion, kidney stones, and abnormal heart rhythm.
There’s a very important message here. If a little is good, more is not necessarily better. And self-medicating with potentially toxic doses of any vitamin or mineral can have potentially dangerous results. Don’t do it. Doctors may prescribe more than 4,000 IU to correct a vitamin D deficiency.
How To Increase Your Vitamin D3 Naturally
- Food sources of vitamin D3 include oily fish and fish oil, egg yolk, butter, and supplements. Plant sources of vitamin D2 include mushrooms exposed to sunlight or UV light, fortified foods, and dietary supplements. Formerly it was advised that since vitamin D is a fat-soluble vitamin you should take your D3 with your largest meal of the day. However, the VitaminDCouncil.org cites studies that show that absorption is not significantly different whether you take vitamin D with food, in pill form, or in a powder. The takeaway about diet and vitamin D is that it’s unlikely that you’re consuming adequate vitamin D from diet alone, which is why you need some …
- Sunlight! For lighter skin, 15-30 minutes of mid-day sun daily. For darker skin, 30 minutes. Your body will not make more D3 than it needs; however, overexposure to the sun holds its own hazards. Since in Cuenca we live much closer to the sun, you may need less exposure than what’s recommended for the general public. You just never want your skin to burn so ten cuidado. And of course, the American Cancer Society advises steering clear from any type of tanning bed.
- Vitamin D3 supplements are generally manufactured from lanolin in sheep’s wool or from fish oil and are shown to be more effective at raising blood levels, however, vitamin D2, sourced from plants, can certainly help. PrecisionNutrition.com reports that daily vitamin D2 supplements are as good for preventing deficiency and protecting vitamin D status as animal-based vitamin D3.
How to tell if you have enough D?
Vitamin D lab tests generally assess the total volume of 25-Hydroxyvitamin D (25(OH)D), which is the form of vitamin D circulating in blood. They may also provide information levels vitamin D2 and D3.
Serum 25(OH)D greater or equal 20 ng/mL (nanograms per milliliter) or 50 nmol/L (nanomoles per liter) is generally considered the minimum adequate level for bone and overall health in healthy individuals.
A concentration below 20 ng/mL is generally considered inadequate, requiring supplemental treatment.
Consider getting tested to see if your vitamin D level is within normal limits. Speak to your doctor about taking a vitamin D supplement, particularly if you have risk factors for vitamin D deficiency, like age, medications, poor diet, and/or any of the diseases mentioned above that may prevent you from absorbing vitamin D. By the way, your body needs vitamin D to absorb calcium, which is why calcium supplements are often combined with vitamin D. However, they do not need to be taken at the same time.
Finally, reduce excess stored fat so that the vitamin D you do eat is more easily absorbed and metabolized. Getting to a healthy weight can also reduce your risk for type 2 diabetes, heart disease, arthritis, some cancers, and more.
Susan Burke March, a Cuenca expat, is a Registered and Licensed Dietitian, a Certified Diabetes Educator who specializes in smart solutions for weight loss and diabetes-related weight management. She is the author of Making Weight Control Second Nature: Living Thin Naturally—a fun and informative book intended to liberate serial dieters and make healthy living and weight control both possible and instinctual over the long term. Do you have a food, nutrition or health question? Write to her – SusanTheDietitian@gmail.com
European Congress of Endocrinology. Higher levels of abdominal fat may predict vitamin D deficiency.
National Institute on Aging: Vitamins & Minerals.
MedicalNewsToday.com. Vitamin D guidelines may be changed following new study.
Medscape.com. (Registration required) Vitamin D: A Rapid Review.
NutritionAction.com. The latest on vitamin D.
PrecisionNutrition.com. All About Vitamins & Minerals.
PrecisionNutrition.com. Vitamin D supplements: Are yours helping or hurting you?
VitaminDCouncil.org. How much vitamin D comes from food, and how much vitamin D comes from sunlight? WebMD.com. Vitamin D Deficiency.