Reasons You May Need a Vitamin D Supplement This Winter and How to Choose One

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What I wouldn’t give for a bright, summer day right now! Blue skies, the sun warming your skin, getting a nice tan, the synthesis of vitamin D… Okay, maybe you’re not thinking about making vitamin D when you’re sunbathing but it’s a nice perk! 🙂 What is vitamin D? Vitamin D is a fat-soluble vitamin that we make by exposing our skin to the sun or through dietary intake; but the sun’s rays aren’t always strong enough to produce vitamin D and few foods naturally contain it. So, a supplement may be needed. First, let’s look at what foods contain vitamin D and its important roles in the body.

Food Sources of Vitamin D

Vitamin D is provided as D3 (one of two forms of vitamin D) in food. Food sources of vitamin D include:

• Fatty fish (salmon, tuna, swordfish, and sardines)- largest dietary source
• Egg yolks
• Red meat
• Liver
• Some mushrooms

Fortified sources (vitamin D was added to foods that don’t naturally contain it):

• Milk
• Yogurt
• Cheese
• Butter
• Margarine
• Some orange juices
• Some cereals and breads

Roles of Vitamin D

Why do we need vitamin D? Vitamin D is so important and has roles including:

• Calcium and phosphorus regulation (maintaining and building healthy bones)
• Ensures calcium and phosphorus are at optimal levels for all tissues like muscles, nerves, and glands
• Cell growth and development
• Muscle functioning
• LOW vitamin D is associated with increased risk of hypertension, cardiovascular disease, type 2 diabetes, certain cancers, and autoimmune disorders

Okay, so you know where vitamin D comes from (exposure to the sun, fatty fish and fortified sources) and that optimal levels of vitamin D are vital to human life. Even though sun exposure is the most efficient way to obtain vitamin D, there are many environmental factors that influence this production. A 15-30 minute exposure of the skin between 10am-3pm during the summer produces about 10,000- 20,000 IU (international units) of D3, which is up to 35 times the necessary daily amount. Don’t worry, the human body is amazing and has regulations in place to avoid synthesizing too much vitamin D from the sun. The point is, that during certain months and above certain latitudes, you can produce adequate vitamin D but you may not get enough during the winter months.

Factors that Influence Vitamin D Production

These environmental factors decrease the efficiency of synthesizing vitamin D:

1. Sun exposure in the early morning or in the evening (not from 10am-3pm)
2. Living above 35 degrees North or below 35 degrees South latitude (fewer UVB rays reach the earth’s surface due to the angle of the sun, decreasing the skin’s ability to produce vitamin D)
3. Older age (older adults can produce 75% less vitamin D)
4. Darker skin color (higher melanin content means longer sun exposure is needed)
5. Sunscreen
6. Clothing
7. Windows (exposure to sunlight through glass will not result in vitamin D production)
8. Pollution

35 degrees N latitude crosses the U.S. from California to North Carolina

Alright, what’s the take away from all these influences on producing vitamin D? The ideal situation for producing vitamin D in the skin is exposing the arms and legs to direct sunlight for 15-30 minutes without sunscreen, sometime between 10am-3pm during the summer months (May-August in the U.S.) in a low polluted area. Gesh, why can’t it ever be simple? Hint, hint- nothing is ever simple in the human body. What I’m getting at is a vitamin D supplement may be necessary in certain areas and time of the year.

Recommended Amount of Vitamin D

The RDA (recommended daily allowance), or much vitamin D you need per day is:

• 1 year- 70 years = 600IU (15ug)
• Older adults >70 years = 800IU (20ug)

However, even the RDA may too low and taking more than this, even up to 10,000 IUs, has been found to be safe in many studies.

My final recommendation is to soak up the sun when you can! Expose your arms and legs to direct sunlight, without sunscreen, for 15-30 minutes at least 3 times/week during the summer months. Consume fatty fish like salmon, tuna, and sardines at least twice per month; they have way more nutritional benefits than vitamin D! During the fall, winter, and spring months take a vitamin D3 supplement (D3 is more efficiently absorbed than D2) containing at least 600IU. If you’re an older adult take a vitamin D supplement year round. Finally, make sure your supplements are always third party tested, meaning they are tested to ensure you’re getting what’s on the label. Look for these major third party tester symbols on your supplement’s label:

This is the vitamin D supplement I take during the winter months from Nature Made: (This is an affiliate link and I will earn a commission on any purchases made through this link)

To learn more from health professionals, including myself, check out the most common health mistakes people make as told by 80 health professionals!

Please comment on this post or contact me directly with questions! Are you getting enough vitamin D?