Adding Vitamin D for the Winter Months – Guest Post – Kelli Jennings

Regular readers know that I am a nearly daily bike rider here in Chicago. As such I read some cycling blogs, too. One of my faves is Loving the Bike.

And, one of that blog’s regular contributors is Kelli Jennings, an Expert Sports Nutritionist who writes Ask the Sports Nutritionist.

Kelli is not only a world class athlete, but also a first rate nutritionist who writes clearly and accurately about her healthy and intelligent eating.

She recently wrote an item Adding Vitamin D for the Winter Months that I thought would interest you. Most importantly, you do not have to be a cyclist to benefit from Kelli’s information. I have written about Vitamin D as beneficial to every person. These ideas should benefit you, too, whether you ride a bike or not.
If you are out on your bike most days, you likely believe you get plenty enough sunshine to make plenty enough Vitamin D.  I get it.  I’m lucky enough to live in a state that boosts more than 300 days a year of sunshine.  So, how come so many of us are Vitamin D deficient?


If you’ve never had your Vitamin D levels checked, you may be in for a surprise.  And, if you find your motivation and mood wavering and eventually diminishing each year in the cold-weather months, you may just find out why.

In fact, it’s not only an issue for athletes, but it’s estimated that at least 25-50% of adults in the United States are deficient in Vitamin D; which is a bit ironic, as it is the only vitamin that our bodies are able to produce (with adequate sunlight).  However, it may be this ability to produce it that gives us a false sense of optimism and a lack of urgency in eating Vitamin D food sources and supplementing.  There are many reasons why we become deficient, and even more reasons to make sure you’re not.

So, what are the implications for cyclists and how can you get enough?

It’s long been known that Vitamin D is important for the absorption of calcium, and therefore, for bone health.  In fact, it was historically thought that the main benefit of Vitamin D was to reduce risk of rickets.  In the last two decades, however, more and more research is finding that Vitamin D’s reach goes far beyond bones.  In fact, it has significant implications on overall health and wellness, respiratory infections, athletic performance, and mood.

Here’s what every cyclist needs to know:
Vitamin D for Athletic Performance:

Reduces Inflammation: After intense exercise, elevated levels of pro-inflammatory cytokines circulate throughout athletes’ bodies.  Vitamin D, along with omega-3 fats from fish oil, reduce the production of cytokines, while increasing the production of anti-inflammatory components.  This can improve recovery, reduce fatigue, and improve overall health.
Improves Immune Function: In studies, Vitamin D deficiency has been correlated with colds, influenza, and respiratory infections. On the other hand, adequate levels of Vitamin D trigger our immune system macrophage cells to release antibacterial peptides, which play a role in infection prevention.  If you want to stay well this Winter, get your Vitamin D.
Prevents Muscle Weakness and Fat Accumulation in Muscles:  Vitamin D deficiency is associated with elevated fat accumulation in muscles, which in turn reduces muscle strength and performance.  In at least one study, the deficiency and loss of muscle strength was demonstrated independent of muscle mass…muscle was actually displaced with fat AND weaker than it should be.  What’s more, there is evidence that supplementation of Vitamin D in deficient persons increases fast twitch muscle fibers in number and size, and reduces injuries (in athletes) and falls (in elderly).
Improves Overall Performance: Studies have shown a steady decline in performance in low-sunlight months, improved performance when athletes are exposed to UV rays (1950s), and peak performance when blood levels of 25 (OH) D are at or above 50 ng/mL.  What’s more, maximum oxygen uptake, or VO2 Max, drops in athletes in months when less UV rays reach the Earth, such as in late Fall months.
Vitamin D for Overall Wellness:
In addition to athletic performance, Vitamin D’s also important for:

Regulating Blood Pressure
Normalizing Blood Sugars and Insulin
Preventing Cancer, especially bladder cancer, breast cancer, colon cancer, ovarian cancer, prostate, and rectal cancer
Steady Moods and Prevention of Depression

Now that we know how important Vitamin D is, it’s no wonder that many experts believe the recommended amounts, and  “normal ranges” for lab values should be much higher than previously established.  But what other factors contribute to our seemingly inadequate intake and levels?
1. We simply live, work, and even workout indoors too much.  Think about the Winter months…how many times have you complained that you get to work and leave work in the dark?  It’s during these short-day months that you must proactively get out and get some sunlight – take advantage of lunch breaks or any daytime opportunity to get outside.
2. There aren’t many good food sources for Vitamin D, and of those there are, we’re not eating enough.  You can find vitamin D in: Herring (1613 IU in 3.5 oz.), Wild Salmon (981 IU in 3.5 oz.), Tuna canned in Oil (200 IU in 3.5 oz.), Milk (100 IU in 8 oz.), Eggs (18 IU in 1 large), Cheese (12 IU in 1 oz.).  Many of our foods are also now lower in Vitamin D – farm-raised fish contain lower amounts than wild fish and caged hens produce less in eggs than those that are not caged.
3. Vitamin D synthesis works best in healthy cells.  Cells in adults who are obese or even overweight, who are not in good health,  or who are elderly may not make as much Vitamin D as they should.   In many cases, those who need the benefits of Vitamin D the most make the least.  Furthermore, those with darker skin pigmentation make less Vitamin D than those with lighter skin pigmentation.
4. While sunscreen is obviously needed to reduce risk of skin cancer and harm to skin, it also reduces Vitamin D production.
How to Increase Your Vitamin D:
1. Get some sun (within reason).  It only takes 10-30 minutes of midday of exposure in Spring/Summer to maximize your body’s Vitamin D synthesis at the equivalent of 10,000 IU (depending on skin tone, health, and age).
2. For maintenance, supplement with D3 at these levels: 1000 IU to 2000 IU in Spring/Summer if you don’t get out in mid-day sun; and, supplement with 2000 IU to 3000 IU in Fall/Winter if you live in a latitude north of Atlanta, Georgia (it’s not possible to produce adequate Vitamin D in the winter months at these latitudes because the sun never gets high enough in the sky for its ultraviolet B rays to penetrate the atmosphere).
3. If you are concerned about a deficiency, get your level checked.  Ask for a for total 25(OH)D, not 1, 25(OH)D.  Vitamin D deficiency is usually identified as

Vitamin D is crucially important to us as cyclists and humans.  If you are not deficient, it’s important to continue to maintain good levels throughout the Fall and Winter.  If you are deficient, it’s important to take the steps above to improve your levels in a efficient manner.

You can make a huge difference in your immune function and overall health this year.  We’re heading into cold-weather, distant-sun months.  Take care with your Vitamin D status.

I would just like to add that there are several other posts on Vitamin D worth checking: How Good is Vitamin D for you? Calcium and Vitamin D Help Hormones Help Bones,Vitamin D and Your Body – Harvard, Can a Vitamin Help Reduce My Waistline?


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Filed under biking, bones, sunlight, Vitamin D

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