Cancer Prevention: What Should You Do?
February 9, 2004
Vitamin D, Calcium, Magnesium, and Cancer
Be sure that your average daily intake of calcium, vitamin D, and magnesium meets the recommended daily allowances for these crucial nutrients.
How Much Will It Help?
My hope is that this will reduce your chances of getting colorectal, and breast or prostate cancer (and probably a number of other common varieties of cancer) by 50% or more. But at a minimum, it should reduce somewhat your chances of developing cancer, and certainly enough to be worth taking care to get the recommended daily allowances of vitamin D, calcium, and magnesium.
The Recommended Daily Allowances of Vitamin D, Calcium, and Magnesium
The recommended daily allowance of vitamin D is:
200 I. U. a day if you're under 30,
400 I. U. a day between 30 and 70, and
600 I. U. a day if you're over 70);
of calcium is:
1,000 mg. a day if you're under 50, and
1,200 mg. a day if you're over 50); and
of magnesium is
400 mg. a day.
(My Nutrition and Vitamin Therapy book suggests that 400 mg. a day is a bit low
for magnesium, and recommends 500 to 600 mg. a day.)
Magnesium has a calming effect. Symptoms of an oversupply of magnesium are drowsiness and stupor. The heart, kidney, and bones contain 66% of the body's magnesium.
You can't go wrong with the above RDA dietary intakes of vitamin D, and they would be particularly important in the
wintertime, when the days are shorter, the sun is lower, and the sky may be
Of course, if you work outside all winter, vitamin D supplementation probably won't be as crucial.
Why This Has Become So Important:
This has always been one of these "you should do's" for bone health, but now, we're learning that this is our best defense against cancer and some other degenerative diseases such as multiple sclerosis.
Sources of Vitamin D, Calcium, and Magnesium
Your total intake of vitamin D comes from three sources: sunlight, diet, and supplements.
Vitamin D, calcium, and magnesium metabolisms are closely intertwined.
Dietary Sources of Vitamin D, Calcium, and Magnesium
Dietary sources of vitamin D typically include milk and fish. Dietary sources of calcium include milk, and these days, other products such as orange juice, cottage cheese, etc.
Salmon typically provide 100 I. U. of vitamin D and 50 mg. of calcium per ounce of salmon, or 400 I. U. of vitamin D and 200 mg. of calcium in a 4-ounce serving.. Usually, in supplements, about 100 I. U. of vitamin D is packaged with every 300 mg. of calcium, so salmon give a much higher level of vitamin D for the amount of calcium they contain (principally in the bones).
Fortified milk contains 100 I. U. of vitamin D and 300 mg. of calcium per cup (about 230 ml.).
Magnesium levels aren't listed in most lists of ingredients. Magnesium is found in whole grains, nuts, green vegetables, milk without supplementary calcium, and seafood.
In 1998, I developed an irregular heartbeat. It turned out that I had a low serum magnesium level.
So it can happen.
Levels of Vitamin D/Calcium Versus Cancer Risks
The estimated daily intake of vitamin D that gives the Japanese low rates of breast and prostate cancer is 1,000 I. U. a day from dietary sources (fish). One study of prostate cancer among men showed that those men who got more than 735 I. U. had the lowest rates of prostate cancer among men.
But... Too High Levels of Vitamin D in the Blood Can Up the Risk of Prostate Cancer
On the other hand, one large and well-regarded Finnish study, appearing in the January, 2004 issue of the International Journal of Cancer, showed that men with the lowest levels of vitamin D had 50% more prostate cancer than those who had an average level of vitamin D in their blood. However, men who had twice the average level of vitamin D in their blood had a 70% higher rate of prostate cancer than those who had an average level. (It's worth noting that there were 622 men with prostate cancer in the study, all from Finland, Sweden, and Norway. This would be an area in which
Hereditary Adaptations Could Make a Difference
People who have evolved in a certain kind of environment... the near-arctic or the tropics... could have genetic adaptations to their environments that would differentiate them from others. For example, the Inuit and the Japanese might have adapted to higher levels of vitamin D than other isolated groups who couldn't handle the amounts of fish that Eskimos and the Japanese might routinely consume as part of their fish diets.
The Inuit might have survived only because they had fish diets that gave them vitamin D in a region where it's virtually unavailable from sunlight during the winter months.
work outside, or
if you live in an area such as southern California, southern Texas, or southern Florida, where the winters are sunny, and you get a certain amount of exposure to the sun,
you may get enough vitamin D from sunlight that you don't need supplements. A
great advantage of sunlight is that the body automatically limits the amount of
vitamin D it produces so that you don't get too much of it. This suggests that,
during the winter, you might get the recommended daily allowance of vitamin D
through a combination of supplements and diet, and then top it off with some
exposure to sunlight to the point where the body cuts off vitamin D synthesis.
How It Might Have Worked in Prehistoric Times
What I'm going to present here are my own speculations regarding how this might have worked in the distant past.
Insofar as we know today, humanity originated in Africa. In Africa, and particularly, in equatorial Africa, dark skins are mandatory to protect furless humans from skin cancer. Human tribes that spread across the tropics have retained these black skins. Polynesians and Micronesians have black skins, as do the peoples of New Guinea.
Tribes that migrated north into the Middle East and then farther north into Europe and into central and northern Asia had difficulty getting enough sunlight through their black skins to synthesize vitamin D, which we now know to be crucial not only to bone health but also to cancer prevention. These northerners must have adapted by developing lighter skins.
The natives of northern Africa in northern Morocco, Algeria and Tunisia, at northern latitudes in the low 30's, evolved lighter skins than humans native to equatorial Africa.
Something similar must have occurred in South Africa, where, again, latitudes are in the lower 30s.
By the time the hominids spread into the Middle East, and then along the north-shore of the Mediterranean, into countries such as Greece, Spain, Italy, and other southern European countries, the latitudes were approaching the 40s, and skins lightened to the olive complexions we see in southern Europe today.
Moving still farther north, we see lighter and lighter complexions until, in the belt of latitudes that includes the Scandinavian countries, complexions are the fairest of all, and blond hair and blue eyes appear (apparently originating there and nowhere else in the world). The most northerly of these peoples can't tan and have the least protection from the sun, having traded the ability to tan for skins that can best extract the most ultraviolet from the wan sunlight in these sub-arctic zones.
Primitive peoples would have spent much of their days outdoors, exposed to the elements. Furthermore, in the temperate zones, trees would have shed their leaves during the winter, allowing more sunlight to fall upon the hairless humans.
Another source of vitamin D in the winter months would have been the vital organs of the game that these winter hunters would have to have bagged to survive in the snow. (It is claimed that primitive humans, like carnivorous animals, ate the vital organs of their prey before turning to muscle meats.) Calcium and magnesium would have been available in the victims' bones.
Similar evolutionary adaptations must have occurred in other parts of the world, with black skins in equatorial Asia, and light skins in northern Asia (e. g., the Koreas and northern Japan).
How It Works Today
The world is very different today. Many white-skinned people have settled in the tropics, and many dark-skinned equatorial people have settled in temperate and even sub-arctic regions... far from the haunts for which nature designed them.
For palefaces settling in the tropics, this means a higher risk of skin cancer, controlled with clothing and sunscreens.
For equatorial peoples settling in temperate and sub-arctic zones, this dissonance may have more sinister effects, resulting in higher rates of deadly cancers. Prostate cancer rates among African-American health professionals are 1.8 times those of their Caucasian colleagues!
In the meantime, we no longer spend the majority of our winter days outside where the sun can reach us. We're also aware of the risks of skin cancer, and are trying to reduce our exposure to the sun's rays. In addition, we no longer eat much liver, because of its high levels of cholesterol, and we no longer eat the bones of animals (except in canned fish).
Dark-skinned people are at special risk because of their reduced ability to synthesize vitamin D. This can be easily rectified, but most of us are unaware of this risk.
So What Should You Do?
I wish I had a clear-cut answer. Maybe when I learn more about this topic, I will, but right now, the only recommendation I would give would be to make sure that, on the average, I get the recommended daily allowances for calcium and for vitamin D, and that I also get a little sunlight, preferably on parts of my body other than my head and neck (since they've already had a lot of exposure). Fortunately, it doesn't take much sunlight to synthesize enough vitamin D.