Vitamin D: The Strong-Bone, Anticancer Vitamin
There are some pairings where you can't imagine one without the other: Bonnie and Clyde, Abbott and Costello, Charlie Brown and Snoopy. The same is true for calcium and its vital partner, vitamin D.
Vitamin D is essential for proper absorption of calcium. Vitamin D helps strengthen bones and prevents the joint deterioration that accompanies arthritis. Vitamin D and its metabolites appear beneficial in reducing certain kinds of breast, colon, prostate, and lung cancers. No one is exactly sure why it works as an anticarcinogen, but both animal studies and one major epidemiologic study on humans showed this to be true. One of the most important vitamins in your Age Reduction Plan might be vitamin D.
Vitamin D may also help protect the body from the onset and ageing effects of arthritis itself, but this finding is still somewhat speculative. Osteoarthritis is a disease that afflicts more than 10 percent of the population sixty-five or older. It is painful, disabling, and ageing. Recent studies from Framingham, Massachusetts, and elsewhere have shown that taking calcium, vitamin C, and particularly vitamin D can retard the progression of arthritis and perhaps even prevent it. These studies found that those who had high levels of vitamin D in their bodies had less joint deterioration and fewer of the painful bone spurs and growths that can accompany arthritis as it worsens. Arthritis patients with low levels of vitamin D and calcium were reported to be three times more likely to suffer the rapid progression of the disease than those who had high levels of these nutrients in their bodies. Arthritis caused them to age faster.
Importantly, vitamin D seems to help prevent cancers. Although no one knows exactly why, and confirming studies are yet to be done, three primary theories try to explain how vitamin D works as a deterrent to cancer. All three have some validity, as evidenced by both animal and test-tube studies, but we still lack confirmation from studies on humans.
The first theory speculates that the D3 form of the vitamin kills cells which contain DNA mutations. Somehow, vitamin D3 is directiy lethal to mutated, possibly cancerous, cells. The second theory suggests that vitamin D3 promotes the death of cancerous cells. The body has an internal mechanism by which it is able to recognize mutated cells, and vitamin D3 is an essential component used in the body's attempt to rid itself of these cells. The final theory proposes that vitamin D3 promotes protein transcription; that is, it helps make proteins from the P53 gene, a gene that is one of the body's cancer watchdogs. Vitamin D appears to be vital for the proper functioning of the P53 gene. This gene helps prevent cancer by regulating the protein production of specific oncogenes—genes that, when mutated, can cause cancers. Indeed, vitamin D not only helps in the proper functioning of the gene but also appears actually to help safeguard the P53 gene from genetic damage.
Although studies still need to be done to confirm the link between vitamin D and cancer prevention, it is very possible that vitamin D does double duty by helping to prevent ageing of not only the skeletal system but also the immune system. When I think of vitamin D, I think of 'defense.' Vitamin D helps you defend yourself.
Most American adults do not get enough vitamin D. Estimates are that 30 to 40 percent of adults are vitamin D-deficient. You get vitamin D from two and only two sources: first, the sun; and second, food and supplements. Let me explain how our bodies produce vitamin D from sunlight.
Vitamin D production is a three-stage process. In the first stage, the body takes in food that contains a kind of cholesterol that is the precursor to vitamin D. Our bodies can't use this cholesterol form of the vitamin without first converting it. Only a few foods, such as cod liver oil and certain fatty fishes (tuna; salmon; sardines; and, to a lesser extent, cod itself) naturally contain vitamin D in the form that can be used by our bodies. For conversion, the second stage, we need sun. Solar radiation is necessary to create the right chemical reaction in our bodies to turn these cholesterols into vitamin D. In the final stage of the process, the liver and kidneys convert that vitamin D into yet another form of the vitamin, vitamin D3, the active form that our bodies can use. As mentioned in the section on sun exposure (see Chapter 5), you need just ten to twenty minutes of sunlight a day to ensure that your body is producing enough vitamin D. Most of us do not get enough sun, particularly in northern climates. In Boston or Seattle, for example, it is almost impossible to produce the necessary levels of vitamin D from sunlight alone from November through February. After we reach our seventies, the precursor to vitamin D generally found in our skin diminishes three or fourfold, making it increasingly difficult for us to produce vitamin D naturally.
The second and less risky way of getting enough vitamin D is through food and supplements. Some foods, mainly fish and shellfish, contain vitamin D naturally. Such foods as milk (the major source of vitamin D in food) and most breakfast cereals contain vitamin D as an additive. These additions, which help prevent rickets (a vitamin D-deficiency disease) in children, are synthetic. When it comes to getting vitamin D, it is no better for us to drink milk than to take a pill. When you drink milk—you get the added benefits of calcium and protein. As I mentioned earlier, most adults do not drink milk in sufficient quantities to get their vitamin D from diet alone.
So how much vitamin D do you need to get the maximum antiageing protection? The RDA of 55 IU only ensures a level of vitamin D that prevents a deficiency disease, such as rickets. I recommend that you consume at least 400 IU of vitamin D a day in a vitamin supplement if you are under seventy years old, and 600 IU if you are older than seventy, unless you are absolutely sure that you are getting enough from your diet. This amount is what I consider the RAO. That means four glasses of milk a day (for 400 IU). Vitamin D overdoses are exceedingly rare among adults. To develop toxic levels of vitamin D in your blood, you would have to consume more than 2,000 IU a day for more than six months.
In addition to the supplement, I recommend getting some sunlight. Ten to twenty minutes a day outside without sunscreen should provide sufficient vitamin D protection, although the farther north you live, the less likely it is that you can produce all the D you need this way. If you are going to be in the sun for more than twenty minutes, put on sunscreen. Note that an SPF 8 sunscreen reduces your vitamin D production by 95 percent, and SPF 30 cuts it to zero. The risk of skin cancer from a little bit of sunlight is probably less than the benefits you gain from having healthy vitamin D levels, especially the older your calendar age. Finally, if you are worried about vitamin D deficiency, you can ask your doctor to test your blood levels. The test will quickly determine whether you are getting enough vitamin D.
Vitamins E and C work as a team. Calcium and vitamin D work as a team. Now let's look at a vitamin that works all on its own—folate, a member of the vitamin B family.