In this monologue Dr. David Perlmutter explains why vitamin D deficiency is a common problem and why it matters far beyond bone health. He notes that vitamin D activates more than 900 genes, influencing cancer risk, inflammation, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Typical laboratory “normal” ranges (30‑100 ng/mL) are insufficient; he advocates an optimal serum level of roughly 70‑80 ng/mL. Modern lifestyle factors—clothing that blocks sunlight and widespread cholesterol‑lowering efforts that reduce the precursor needed for skin‑based vitamin D synthesis—contribute to low levels. He recommends a personalized supplementation approach: start most patients on about 5,000 IU daily, re‑measure serum vitamin D after about two months, and adjust the dose to reach the target optimal range.
Chapters
One of the biggest deficiencies that we see when we do blood analysis of our patients in terms of vitamins is vitamin D. Vitamin D is well beyond simply being important for strong bones. In fact, vitamin D activates more than 900 genes, 900 parts of our DNA, reducing our risk for things like cancer, inflammation. Low vitamin D levels are associated with cognitive issues like Alzheimer's disease and even Parkinson's disease. So vitamin D turns out to be a big player. We oftentimes don't have enough vitamin D. When, again, when we see people, typically their vitamin D levels are suboptimal. Now the normal range of vitamin D is, let's say, between 30 and 100. So some people will go to their doctor and he or she will say, well, your level is 31. That's great, you're in the so-called normal range. The Grain Brain program is not about getting into the normal range, it's about getting into the optimal range. You want to ask your doctor to help you get to a vitamin D level of around 70 or 80. That's what seems to be best. Why do we have such low levels of vitamin D? Well, most of us these days wear clothes. In our hunter-gatherer days, we would go around naked. And as such, our skin would get ultraviolet radiation from the sun, and we would turn a specific chemical in our body into vitamin D. Now it turns out that these days everybody is doing their best to get rid of that precursor chemical that makes vitamin D. That chemical is cholesterol. So with all these great efforts to lower cholesterol, we're actually lowering the very chemical that our body needs to make vitamin D. It's difficult for me to prescribe to a patient how much vitamin D he or she may need. It's all about the blood test. Typically, a patient might need 5,000 units a day. You might need 5,000 units a day, but again, what we normally do is give a patient, an individual, a dosage of 5,000 units and then recheck the vitamin D level in about 2 months and adjust the dosage.
