Yesterday, I offered a timely reminder on the importance of your cardiorespiratory fitness in slashing your stroke risk — and your risk of any form of heart disease in general.
The stroke reduction benefit is impressive, even by my standards. But according to another recent study, exercise may not be your only way to get it. And a healthier heart could literally be waiting right outside your door…
Get fit with a daily dose of sunshine
Simply put, cardiorespiratory fitness determines how efficiently your heart, lungs, and blood vessels can supply oxygen to fuel your muscles during exercise. And it’s usually measured by VO2 max — the peak amount of oxygen you take in during a workout.
People with higher levels of cardiorespiratory fitness are just plain healthier. But research shows that exercise may just be only one way to get there. And that another path is supplementing with vitamin D.
This study looked at a cross-section of Americans between the ages of 20 and 49. Using data from the National Health and Nutrition Survey (NHANES) in 2001-2004, researchers assessed the serum vitamin D and VO2 max levels of nearly 2,000 men and women.
They then separated subjects into quartiles according to their D levels, where some striking differences arose.
For one thing, subjects with the highest vitamin D levels had cardiorespiratory fitness levels that were more than four times higher than subjects with the lowest levels. And even after accounting for major factors like age, BMI, smoking, high blood pressure, and diabetes, high levels of D still tripled cardiorespiratory fitness.
In fact, every unit increase in serum vitamin D delivered a statistically significant boost in VO2 max — suggesting a clear dose-dependent response. This is one case where more isn’t just better — it’s absolutely necessary.
Why longer days still need a boost of D
You could fill a book with all the ways that vitamin D boosts your health and longevity. It boosts your bone strength, lifts your mood, and wards off every chronic condition from obesity to cancer, just to name a few.
That’s why it’ll always have a place on my list of “must-have” supplement recommendations. And why I always feel the need to remind you that, yes, you still need to be taking it — even in the summer, and even if you’re active outdoors.
It’s true that sunshine is your best source of vitamin D. And you can definitely supplement with lower doses of D during the warmer months IF you get full mid-day sun exposure over most of your body. Without sunscreen. For 20 minutes per day. Every day.
But in order to stop supplementing altogether, you’d also have to live in South Florida or the very Southern part of Texas. If you don’t, you absolutely must take your vitamin D.
That’s because a level of 30 ng/ml — which most doctors consider to be perfectly adequate — still isn’t anywhere near optimal. You really need to aim closer to 80 ng/ml instead. And as usual, most people are going to need a lot more than the recommended daily allowance (RDA) of D3 daily to get there.
I generally recommend a minimum of 2,000 to 5,000 IU daily, year-round. And if you don’t get outside much, you may need as much as 10,000 IU. (Which is perfectly safe with regular monitoring.) You won’t know for sure until you get tested. So if you haven’t had your levels measured lately, ask your doctor to check them today!
P.S. – I talk more about the benefits of vitamin D and how you can increase your intake in the July 2017 issue of my Logical Health Alternatives newsletter (“The completely natural, pill-free way to slash your risk of heart attack”). The health benefits of vitamin D go way beyond heart health!
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“Vitamin D levels in the blood linked to cardiorespiratory fitness.” Science Daily, 10/30/2018. (sciencedaily.com/releases/2018/10/181030091449.htm)