 the best way to optimize your vitamin D. Well, interestingly enough, it's been shown that cultures that get adequate sun exposure tend to live longer. In fact, four out of the five blue zones are actually in high sun exposure areas, including my former blue zone, Loma Linda, California. But Okinawa is actually in the subtropical region of Japan, but Okinawa winters tend to be actually kind of dark and rainy and cloudy, so they are probably the exception to the blue zones enjoying great sunlight. Well, it's important to get vitamin D levels adequate. Now, you can get adequate vitamin D levels with sun exposure. In fact, a very famous professor from Boston University, Dr. Hollick, who is a dermatologist, became notorious a number of years ago by recommending that people spend 15 to 20 minutes a day exposing themselves to sunlight. And I won't go into all the mischief he got into by saying that, but he's subsequently been proven correct that sunlight exposure is very important. Now, when you expose your skin to sunlight, you will make the active form of vitamin D, which is vitamin D3. And that's important because the good news is, swallow the same vitamin D3 as a supplement without having to expose yourself to the sun. Vitamin D is a critical vitamin. It's actually a hormone, more than a vitamin, that is critical for our immune system functioning. It's critical for our brain functioning. In fact, depression has been linked to low levels of vitamin D. It's incredibly important during pregnancy. A study out of South Carolina reported that gestational age was influenced by a mother's vitamin D status and that infants that were born prematurely were in moms who were vitamin D deficient. So if you're thinking about getting pregnant, if you're pregnant, make sure you're getting adequate amounts of vitamin D and we'll talk about that in a moment. Vitamin D deficiency also increases the risk for muscle weakness and frailty. Vitamin D is essential to actually keep our gut wall intact. There's very fascinating studies that vitamin D promotes stem cell proliferation in the wall of our gut. And if you've been following the excitement about stem cell research, you know that having activated stem cells is probably a pretty good idea. We also know that people who have the highest levels of vitamin D tend to live the longest, not only live the longest, but live the healthiest as they age. So a lot of good reasons to keep our vitamin D levels high. Now, there's a fallacy out there that because vitamin D is a fat-soluble vitamin that you have to eat fat when you swallow vitamin D to absorb it. And in fact, Professor Hollick in Boston showed in human experiments that there's no need to have fat in your diet to absorb vitamin D. In fact, you can actually find powdered vitamin D capsules with no fat, and they're perfectly acceptable, although most vitamin D capsules do are in a fat capsule. But the point is you do not have to eat a fatty meal. You don't have to have an avocado when you swallow your vitamin D capsule to make it absorbable. Yes, it is a fat-soluble vitamin, but that doesn't mean you will not absorb it without having fat in your diet. It's one of the great vitamin D myths. All right, how do you know if you're getting enough vitamin D? Well, sun exposure is one way of basically assuming you're getting a baseline level. But it takes a significant amount of sun exposure to get an adequate level. Most people can achieve a vitamin D level of 50 to 60 nanograms per deciliter with about an hour of sun exposure per day. But remember, that's 365 days a year, and I can guarantee you most people aren't getting that much sun exposure unless you're Joseph Mercola. On the other hand, many people unfortunately don't have the right vitamin D receptors on their cells so that even some people who get a lot of sun exposure don't have adequate levels of vitamin D. So first of all, get your vitamin D level measured. It's a simple test. It's cheap. Any doctor can order it for you. Now, the federal government's levels are incredibly low. They say that 30 is normal and that only in the 20s are you deficient. In my practice, I want people to have vitamin D levels around 100 to 150. If you have a Quest Lab or a Cleveland Clinic Heart Lab, they will tell you that a normal vitamin D level is up to 150. The University of California, San Diego, has done extensive research into vitamin D levels in humans, and they have not found vitamin D toxicity up to people taking 40,000 international units of vitamin D3 a day, 40,000 a day, and that they've calculated that the average American should be taking 9,600 international units a day of vitamin D3 to have an adequate level. That's a lot of vitamin D. Now, I think bare minimum, you should be taking 5,000 international units of vitamin D. All my patients during the COVID epidemic, I doubled their vitamin D3 levels. There are now 19, actually there was a new one last week out of Israel, that show the higher your vitamin D level, the safer you are from COVID, and if you catch COVID, it will be a mild illness, and that's certainly my experience in my two clinics. Interestingly enough, there was a recent study published saying that vitamin D has no effect on preventing colds, flu, or COVID. Additionally, that study looked at the recommended dose of vitamin D, which is only 400 to 800 international units of vitamin D, and of course at that level, it's not going to have any effect, because that level I've never seen anyone achieve a normal vitamin D level taking the recommended daily dose of vitamin D. So do yourself a favor, boost your vitamin D. Now, when you're taking higher doses of vitamin D, I highly recommend that you take vitamin K2. Vitamin K2 escorts calcium out of your blood vessels and into your bones, where of course you'd want it, and it really assists vitamin D in bringing calcium where it belongs, which is in your bones, and you don't need much vitamin K2. 100 micrograms of vitamin K2 is really all you need for adequate levels of vitamin K2. A lot of times you can find a combo pill with vitamin D3 and K2, and that's an easy way to get it. How to get more vitamin D other than a supplement? It's actually really hard to do. Mushrooms are an interesting source of vitamin D, but they're not adequate enough to get enough vitamin D in your life, but don't forget mushrooms have many other beneficial effects than just vitamin D. Last but not least on vitamin D. I have yet to see vitamin D toxicity. Can it exist? I suppose it can. There are reports of people taking massive amounts of vitamin D, a million international units a day developing kidney failure or kidney stones. I've seen a couple of women, and I do emphasize a couple of women, who think, and I believe them, that they get more palpitations when their vitamin D levels go up and when they back off on vitamin D, palpitations get better. Hey, if that's your experience, trust your experience. Even if your vitamin D level is normal or in the range that I want it, and you're getting palpitations and you're pretty sure it's your vitamin D, please experiment. Drop it out for a few days, see if it goes away. But in general, I really have not seen vitamin D toxicity, I've been measuring people's vitamin D levels for 25 years now, and you would think I would have seen it if it could happen. And as many of you know, I'll use a lot of vitamin D in my autoimmune patients. Get some vitamin D in your life. Listen to the University of California, San Diego. Most of us ought to have a pretty close to 10,000 international units a day for good health. I think you're going to love this next one. The University of Orange Juice has as much sugar as a candy bar or a can of soda.