While we’re on the subject of folate, let’s look at a few other little known facts about this nutrient and the dance it does with vitamin D in the sunshine.
Sunlight, more specifically the ultraviolet B (UVB) wavelength of sunlight, when absorbed by the skin destroys folate. The same UVB, when absorbed by the skin, stimulates the production of vitamin D. Since we need both folate and vitamin D, natural selection was presented with a real problem in dealing with both.
In Africa – from where we presumably all came – the intense equatorial sun acting through the forces of natural selection produced a race of dark skinned people. The dark skin allowed enough absorption of UVB to produce plenty of vitamin D, but prevented the absorption of enough to destroy the folate. As people migrated out of Africa into cooler, less sun-exposure intense areas, skin color got lighter allowing more absorption of UVB to produce vitamin D. UVB exposure in these areas – Northern Europe, for example – was not enough to destroy folate because the UVB rays weren’t direct as they are at the equator.
Light-skinned people who get a ton of sun exposure can destroy enough folate to cause problems, but are protected because the UVB rays burn them, driving them from the sun. Those who get progressive sun exposure develop a tan that performs the same function as the naturally dark skin of people living in high UVB exposure areas.
You can pretty much tell how much sun exposure any group of people have been exposed to over the past several thousand years by how dark their skin is. Mediterranean people, for example, are light enough to allow enough UVB absorption to make plenty of vitamin D, but dark enough to prevent enough absorption to destroy their folate. One group of people, however, are an exception to this rule: the Inuit of northern Canada. These people are pretty dark skinned, yet they live in an area with very little strong UVB exposure. But they live on a diet that is predominantly fatty fish. Fatty fish are one of the few foods containing enormous amounts of vitamin D. So, the Inuit get their vitamin D in their diets and didn’t have to evolve light skin.
Another interesting aspect to all this is how it impacts cholesterol levels. Vitamin D is made in the skin from cholesterol. People who live in areas where there isn’t much sun exposure tend to run higher cholesterol levels to trap as much of the tiny UVB exposure as they can. For this reason, if you check your cholesterol levels, they will almost always be higher in winter than in the summer.
Vitamin D is an extremely important vitamin involved in bone building, heart protection, clotting, fighting infection, warding off cancer, enhancing cognition, preventing mental illness and a host of other functions. Most of us are deficient in this vitamin because we live in northern areas, spend a lot of time indoors, and, because of the faulty advice from dermatologists, slather on sunscreen when spending much time outdoors. Sunscreens block UVB and totally prevent the formation of vitamin D. We can somewhat compensate by developing higher levels of cholesterol to trap what little UVB we get and convert it to vitamin D, but now whenever we run our cholesterol levels up a little, we are put on statin drugs to get it down.
One other factoid is that the main protein in the blood, albumin, prevents much of the UVB-induced destruction of folate. Albumin is made in the liver, and levels of it are a marker of liver function. When your liver is compromised, you don’t make as much albumin. If you go on a low-protein diet, you don’t make as much albumin.
Given all these disparate, but related, facts, what is the take home lesson?
There are several.
First, if you are a pregnant woman, be careful of too much sun exposure. If you do get a fair amount of sun exposure, make sure you take plenty of folic acid.
Second, if you don’t get much sun exposure, take a vitamin D supplement. The best are vitamin D3. Don’t take anything but vitamin D3. (I’m planning a major post on vitamin D in the near future, so you’ll know everything you need to know about this incredibly important vitamin.) Take at least 1000 units per day. In the winter, 5000 units per day isn’t too much.
Third, if you choose to take a statin, make sure you take vitamin D. If you’re worried that your cholesterol is a little high, get some good sun exposure or take vitamin D3.
Forth, eat plenty of protein so that you will make enough albumin. This albumin will protect your folate from the ravages of the sunshine that you bask in to increase your vitamin D.
Last, if your worried about your folate levels, take the newer kind of folic acid called methylfolate, which is available from most health food stores and natural food grocers. Read my previous post to learn about this supplement.