Vitamin D: How Much Is Enough? – Your Guide To The Best Sources

It’s still winter. It’s still cold, and rather dark, and sometimes rather wet. And I’m still feeling funky. With the sun disappearing during the cool, Pacific winters, I suffer from lack of vitamin D! I know my body produces it with the sun, and I can get it in my diet. But how much do I need to get out of this funk? I’ve done some digging, to find out just how much vitamin D I need every day – and how I’m gonna get it.

What Exactly Is Vitamin D?

There are two noticeable forms of vitamin D: vitamin D2 and vitamin D3. Vitamin D2 is produced by invertebrates (slugs, snails etc) fungus and plants in response to UV irradiation. It is not produces by us vertebrates.

The form I want to focus on is vitamin D3, which is made in our skin when it reacts with UVB rays. It’s possible to get this vitamin from dietary and supplement sources, and the most powerful source is from the sun!

Vitamin D Requirements: Are You Getting Enough?

Sufficient Vitamin D to maintain bone health and normal calcium metabolism in healthy people looks like this:

Adequate Intakes (AIs) for Vitamin D [4]

Age	Children	Men	Women	Pregnancy	Lactation
Birth to 13 years	5 mcg (200 IU)
14-18 years		5 mcg (200 IU "font-size:small;">)	5 mcg (200 IU)	5 mcg (200 IU)	5 mcg (200 IU)
19-50 years		5 mcg (200 IU)	5 mcg (200 IU)	5 mcg (200 IU)	5 mcg (200 IU)
51-70 years		10 mcg (400 IU)	10 e="font-size:small;">mcg (400 IU)
71+ years		15 mcg (600 IU)	15 mcg (600 IU)

Age Children Men Women Pregnancy Lactation

Birth to 13 years 5 mcg
(200 IU)

14-18 years 5 mcg
(200 IU "font-size:small;">) 5 mcg
(200 IU) 5 mcg
(200 IU) 5 mcg
(200 IU)

19-50 years 5 mcg
(200 IU) 5 mcg
(200 IU) 5 mcg
(200 IU) 5 mcg
(200 IU)

51-70 years 10 mcg
(400 IU) 10 e="font-size:small;">mcg
(400 IU)

71+ years 15 mcg
(600 IU) 15 mcg
(600 IU)

That said, the safest maximum amount to take is 2,000 IU for adults, and 1,000 for children. The amount varies by individual need, based on climate, diet, and deficiency.

How Do You Know If You’re Deficient?

Try upping your protected sun exposure, and foods rich in vitamin D. And ask your doctor for a blood test – your deficiencies will show up!

Vitamin D Deficiencies

A deficiency in any vitamin can produce a variety of health problems. Some serious ailments we know of, caused by a lack of vitamin D, include:

Depression
Obesity
Colorectal, breast and prostate cancers
Autoimmune diseases
High blood pressure
Cardiovascular diseases

Loads of folks are deficient in vitamin D, most especially individuals who are over 60, live at northern latitudes, have darker skin, or are rarely outdoors. According to UC Berkeley’s W
ellness Alerts: “… in Northern US and Canada, blood levels drop markedly in the winter, when days are shorter, the sun is weaker, and we wear more clothes and spend less time outside. Many young people also have low blood levels of D, according to some recent studies. Obesity is associated with reduced blood levels.”

The Most Powerful Source: The Sun

According to many, UV exposure is the most powerful source of vitamin D. Sun exposure needed to produce enough vitamin D depends on time of year, latitude, skin color and age. In a sunny location such as Hawaii, five to 10 minutes of midday sunlight on the arms and face or legs two to three times a week can produce adequate vitamin D in people with light skin. Those with dark skin can require 10 to 50 times the sunlight exposure to produce the same amount of vitamin D. An SPF 8 sunscreen reduces the production of vitamin D by more than 95 percent but helps prevent skin damage, so getting adequate vitamin D in the diet might be the safest approach.The healthiest way to source Vitamin D by sun exposure, is to know your UV index.

UV Index – What It Is And What It Tells Us

The UV index is an international measurement created by Canadian scientists and standardized by the World Health Organization. It tells the general public how strong UV radiation is, to help educate us so that we know how strong the sun may be on a particular day and in a particular place, and we can protect our skin and eyes. As most people know, over-exposure to UV rays can cause skin burns, damage, photo-aging and cancer, and eye damage and cataracts. In general, the higher the UV index, the greater the need for protection – ie. sunscreen, hat, sleeves etc.

UV Index Chart

2 or less: Low

A UV Index reading of 2 or less means low danger from the sun’s UV rays for the average person:

Wear sunglasses on bright days. In winter, reflection off snow can nearly double UV strength.

If you burn easily, cover up and use sunscreen.

Look Out Below

Snow and water can reflect the sun’s rays. Skiers and swimmers should take special care. Wear sunglasses or goggles, and apply sunscreen with an SPF of at least 15. Remember to protect areas that could be exposed to UV rays by the sun’s reflection, including under the chin and nose.

3
- 5: Moderate

A UV Index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure.

Take precautions, such as covering up, if you will be outside.

Stay in shade near midday when the sun is strongest.

Me and My Shadow

An easy way to tell how much UV exposure you are getting is to look for your shadow:

If your shadow is taller than you are (in the early morning and late afternoon), your UV exposure is likely to be low.

If your shadow is shorter than you are (around midday), you are being exposed to high levels of UV radiation. Seek shade and protect your skin and eyes.

6 – 7: High

A UV Index reading of 6 to 7 means high risk of harm from unprotected sun exposure. Apply a sunscreen with a SPF of at least 15. Wear a wide-brim hat and sunglasses to protect your eyes.

Protection against sunburn is needed.

Reduce time in the sun between 10 a.m. and 4 p.m.

Cover up, wear a hat and sunglasses, and use sunscreen.

Made in the Shades

Wearing sunglasses protects the lids of your eyes as well as the lens.

8 – 10: Very High

A UV Index reading of 8 to 10 means very high risk of harm from unprotected sun exposure. Minimize sun exposure during midday hours, from 10 a.m. to 4 p.m. Protect yourself by liberally applying a sunscreen with an SPF of at least 15. Wear protective clothing and sunglasses to protect the eyes.

Take extra precautions. Unprotected skin will be damaged and can burn quickly.

Minimize sun exposure between 10 a.m. and 4 p.m. Otherwise, seek shade, cover up, wear a hat and sunglasses, and use sunscreen.

Stay in the Game

Be careful during routine outdoor activities such as gardening or playing sports. Remember that UV exposure is especially strong if you are working or playing between the peak hours of 10 a.m. and 4 p.m. Don’t forget that spectators, as well as participants, need to wear sunscreen and eye protection to avoid too much sun.

11+: Extreme

A UV Index reading of 11 or higher means extreme risk of harm from unprotected sun exposure. Try to avoid sun exposure during midday hours, from 10 a.m. to 4 p.m. Apply sunscreen with an SPF of at least 15 liberally every 2 hours.

Take all precautions. Unprotected skin can burn in minutes. Beachgoers should know that white sand and other bright surfaces reflect UV and will increase UV exposure.

Try to avoid sun exposure between 10 a.m. and 4 p.m.

Seek shade, cover up, wear a hat and sunglasses, and use sunscreen.

Beat the Heat

It is possible to go outside when the UV Index is 11 or higher. Make sure you always seek shade, wear a hat, cover up, wear 99-100% UV-blocking sunglasses, and use sunscreen. Or you can opt to stay indoors and take the opportunity to relax with a good book rather than risk dangerous levels of sun exposure.

(Courtesy of the US Environmental Protection Agency)

To find out the UV index forecast in your area, click HERE.

The Sun: Friend Or Foe?

But hold on, according to the American Dermatology Association in its 2008 Annual Report To Members, while the sun is a source of vitamin D, “it is also a source of harmful ultraviolet radiation resulting in thousands of skin cancers each year.”.

Also, the ability of the skin to make vitamin D declines with age. At that point food sources of the vitamin become more important. However, there is cause for concern that supplementing with Vitamin D can cause toxicity.

According to the Office Of Dietary Supplements, “Excessive sun exposure does not result in vitamin D toxicity because the sustained heat on the skin is thought to photodegrade previtamin D3 and vitamin D3 as it is formed. High intakes of dietary vitamin D are very unlikely to result in toxicity unless large amounts of cod liver oil are consumed; toxicity is more likely to occur from high intakes of supplements.”

Vitamin D toxicity can cause nonspecific symptoms like:

nausea
vomiting
poor appetite
constipation
weakness
weight loss
raise blood levels of calcium, causing mental status: confusion and heart rhythm abnormalities

Eat Your Vitamin D!

Incorporating Vitamin D into the diet can be a great way to get enough, especially in cooler climates.

Dietary Sources Of Vitamin D – IUs per serving*/Percent DV**

Cod liver oil, 1 tablespoon 1,360/340
Salmon (sockeye), cooked, 3 ounces 794/199
Mushrooms that have been exposed to ultraviolet light to increase vitamin D, 3 ounces (not yet commonly available) 400/100
Mackerel, cooked, 3 ounces 388/97
Tuna fish, canned in water, drained, 3 ounces 154/39
Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup 115-124/29-31
Orange juice fortified with vitamin D, 1 cup (check product labels, as amount of added vitamin D varies) 100 /25
Yogurt, fortified with 20% of the DV for vitamin D, 6 ounces (more heavily fortified yogurts provide more of the DV) 80/20
Margarine, fortified, 1 tablespoon 60/15
Sardines, canned in oil, drained, 2 sardines 46/12
Liver, beef, cooked, 3.5 ounces 46/12
Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV) 40/10
Egg, 1 whole (vitamin D is found in yolk) 25/6
Cheese, Swiss, 1 ounce 6/2

*IUs = International Units.

**DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents of products within the context of a total diet. The DV for vitamin D is 400 IU for adults and children age 4 and older. Food labels, however, are not required to list vitamin D content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.

Great Links! For more info on Vitamin D, check out these links:

Dietary Supplement Fact Sheet

http://www.nal.usda.gov/fnic/foodcomp/search/

To summarize then:

Careful sun exposure is the best source of vitamin D, but difficult to find in northern, colder climates.
Dietary sources are then preferred, being careful not to consume large amounts of cod liver oil.
Lastly, supplementing with vitamin D can be beneficial, but must be regulated. Individuals supplementing must also take into consideration amount of dietary vitamin D consumed, as well as sun exposure.