Takeaways from content we’ve enjoyed & other timely topics
Shorter Days, Bigger Need: Time to Boost Your Vitamin D? ☀️
As the Fall days get shorter, our exposure to sunlight decreases, and it becomes harder for our bodies to produce enough Vitamin D, nature’s “sunshine vitamin.” While most people know vitamin D supports bone health, its benefits are far-reaching. Once absorbed, vitamin D acts as a steroid hormone – it enters the cells and directly influences nearly 1,000 genes, or about 5% of our genome. It not only bolsters bone strength, but also immune defense, brain health, and even mood through serotonin synthesis. Low vitamin D has been linked to fractures, infections, cognitive decline, and higher overall mortality.
When Vitamin D Supplementation Becomes Important
Our skin produces vitamin D when exposed to UVB light, but several factors limit our ability to produce enough of it. These include darker skin pigmentation, limited time outdoors or use of sunscreen, genetics, obesity, and age. At age 70, for example, you produce about 20% of what you did at age 20. In northern latitudes as in Canada, UVB radiation is not high enough for four to five months of the year for us to produce enough vitamin D, making supplementation essential for most people.
Optimal Levels and Supplementation
Optimal blood levels are thought to be around 75 to 150 nmol/L; below 25 nmol/L is considered deficient, and above 250 nmol/L is toxic. Staying in the optimal range is linked to lower risk of fractures, respiratory illness, and even all-cause mortality. Health Canada recommends **400 IU daily for most adults,** with an upper non-prescription limit of **2,500 IU per day**. Research suggests many adults need relatively high doses to reach optimal levels. For example, a daily routine of 1,000 IU Vitamin D3 may raise blood levels by about 10-15 nmol/L. Testing your Vitamin D is the most reliable way to tailor your supplementation. Pairing Vitamin D3 with K2 helps ensure calcium is directed to bones rather than arteries. Foods rich in Vitamin D3 are fairly limited, but include fatty fish, cod liver oil, and egg yolks. Some foods are fortified with Vitamin D, but these typically contain Vitamin D2, which is less potent than D3.
What Vitamin D Can Do for You
Vitamin D helps your body absorb calcium and direct it to your bones, lowering the risk of osteoporosis-related fractures. It also supports muscle strength, which can help prevent falls. Supplementation has also been shown to reduce the risk of respiratory infections. Studies suggest vitamin D may modestly lower the risk of death, particularly in older adults or those who are deficient. Observational research links low vitamin D to dementia risk, and vitamin D plays a role in regulating serotonin, the brain chemical that influences mood and wellbeing.
Testing Matters
In Ontario, OHIP covers vitamin D testing only for specific conditions including osteoporosis and kidney disease, but demand for testing among clinicians and health-conscious consumers remains high. Vitamin D needs are highly individualized, shaped by skin tone, latitude, body composition, and lifestyle. Testing offers a cost-effective way to tailor supplementation, and may help prevent deficiency as well as over-correction.
Bottom Line
Vitamin D is not just a vitamin, it is a hormone that regulates thousands of genes, strengthens bones, fine-tunes the immune system, and may even influence brain health. Because production is inconsistent and food sources are limited, supplementation with D3, ideally paired with K2, is often necessary. Aim for optimal, not minimal levels, guided by individualized testing where possible.
📚 To dive deeper into this topic, check out Rhonda Patrick’s resources on Found My Fitness, delving into vitamin D research and implications. Specifically, check out episodes on vitamin D supplementation, vitamin D’s role in longevity, and a talk with Dr. Bruce Ames on the importance of maintaining optimal vitamin D levels.
