Super Immunity (21 page)

The researchers found that the frequency of colds among people who exercised five or more days a week was up to 46 percent less than that of people who were largely sedentary—that is, who exercised only one day or less per week. These results are stunning—half the number of viral infections for those who were exercising regularly! Furthermore, when these individuals
did
come down with an illness, it was not as severe an illness, and the number of days of being ill was a whopping 41 percent less.
⁶

Exercise not only helps your immune system fight off simple bacterial and viral infections; it also decreases your chances of developing heart disease, osteoporosis, and cancer. The key to the longevity-promoting effects of exercise is maintaining a high degree of exercise tolerance and fitness.

When middle-aged men were followed for twenty-six years, researchers found that those who exercised vigorously lived the longest.
⁷
It truly is survival of the fittest! The same thing is true regarding heart disease prevention.
⁸
In other words, it is not sufficient just to take walks; adding on more exerting exercise, where the heart rate is elevated, and sustaining that elevation for at least five minutes has additional benefits.

I advise you to exercise vigorously, with jogging, jumping in place, and other heart-rate-elevating exercises or activities. Keep your leg muscles and the central muscles in the abdomen and back strong. To achieve maximum benefit, exercise at least three days per week.

That does
not
mean that being involved in competitive triathlons or marathons is lifespan-enhancing.
Extreme
exercise is a major stress on the body and produces excessive free radicals. In most cases, the benefits that vigorous exercise gives us, including the increased functional efficiency in almost all the body's cells, more than compensates for the added physical stress. However, with
extreme
degrees of vigorous exercise, such as extended-length events of competitive running, biking, or cross-country skiing, the stress on the body can exceed the benefits.

First of all, I recommend for most individuals a high-quality multivitamin/multimineral capsule to assure favorable levels of vitamin D, B
₁₂
, zinc, and iodine. Very few of us eat perfectly, and it makes sense to be sure that you ingest adequate amounts of these important substances, especially those nutrients whose levels may be less than ideal even with an excellent diet.

Making sure we have enough iodine is vital, especially because our diet change will limit the amount of salt we ingest. Most grocery store salt has been iodinated, making it the primary source of iodine in most people's diets. Zinc, as discussed earlier, is an essential mineral that can be difficult to ingest in adequate amounts through a healthy diet. For example, zinc does not often reach ideal levels on a vegan or near-vegan diet. Therefore, the right multivitamin can assure adequate iodine and zinc intake to keep our immune systems functioning at an optimal level. However, as you will see, we have to be careful about the other components of the multivitamin.

I have carefully reviewed the studies on every typical multivitamin/multimineral ingredient, and there is clearly a significant risk from supplementing certain nutrients on a regular basis, especially in the dosages found in high-potency vitamin supplements. So even though multivitamins may contain beneficial nutrients, they also contain ingredients that are harmful and may significantly increase one's risk of cancer.

Vitamin and mineral use generally follows a biphasic dose response curve. This means that too little is a problem, a certain middle range is likely ideal, and too much can cause a problem as well. This curve can be clearly observed if we look at the data on vitamin E. Whereas eating foods rich in vitamin E and the various vitamin E fragments is clearly beneficial, taking a
large
dose, such as 200–400 international units (or IU, a standard measure of vitamin potency)—an amount unobtainable from even the richest vitamin E–containing foods—has negative effects.
⁹

Here's what we need to look out for. The riskiest nutrients in a supplement are vitamin A (retinyl acetate or retinyl palmitate) and folic acid. These two nutrients account for the negative aspects of most multivitamins and detract from the overall benefits of taking a typical multi. The strong negative effects of supplemental vitamin A and folic acid may account for why studies on multivitamins are so inconclusive, with some studies showing benefits and others showing none. Overall, there is insufficient evidence to conclude that a multivitamin, as currently constituted, plays a significant role in extending lifespan or reducing the incidence of cancer. However, since science has shown that the negative effects come from only a limited number of supplemental ingredients (discussed below), with the strongest negative effects from folic acid and vitamin A, a study conducted on a properly designed multivitamin, without those ingredients, would probably reveal health benefits.

This potential for a multi, without vitamin A and folic acid, to offer health or lifespan benefits is supported by the evidence that the general use of a multivitamin extends the length of cellular telomeres, which protect chromosomes and help ensure normal DNA replication. Subjects taking a multi were found to have over 5 percent longer telomeres compared to those who did not take a multi on a regular basis. Telemeres shorten with aging, and shorter telomeres are associated with shorter lifespan.
¹⁰

Let's look at some of the potentially troublesome elements of a multivitamin/multimineral in more detail.

Ingesting vitamin A or beta-carotene in isolation—from supplements, instead of from food—may interfere with the absorption of other crucially important carotenoids, such as lutein and lycopene, thus potentially increasing cancer risk.
¹¹
Beta-carotene once was regarded as a safe and beneficial antioxidant and even recommended as an anticancer vitamin, but it has recently been shown to increase the risk of certain cancers when administered as a supplement rather than ingested from food. Scientists now suspect that problems may result when beta-carotene is ingested without other carotenoids that would have been present had it been ingested from real food. Beta-carotene is only one of about five hundred carotenoids that exist. Beta-carotene supplements are poor substitutes for the broad assortment of carotenoid compounds found in plants.

Years ago scientists noted that populations with high levels of beta-carotene in their bloodstream had exceedingly low rates of cancer. Now we understand that the reason these people were protected against cancer was the hundreds of
other
carotenoids and phytochemicals in the fruits and vegetables they were consuming. Beta-carotene served as a flag or marker for those populations with a high fruit and vegetable intake. Unfortunately, many people confused the flag for the ship.

In Finnish trials, people using beta-carotene supplements not only failed to prevent lung cancer; there was actually an increase in cancer in those who took the supplement.
¹²
This study was halted when the researchers (physicians) discovered that the death rate from lung cancer was 28 percent higher among participants who had taken the high amounts of beta-carotene and vitamin A. Furthermore, the death rate from heart disease was 17 percent higher in those who had taken the supplements compared to those given a placebo.

Since beta-carotene gets converted into vitamin A by your body, there is no reason why a person eating a reasonably healthy diet would require any extra vitamin A. The ingestion of extra vitamin A is even riskier than the ingestion of supplemental beta-carotene. In humans, excess vitamin A is potentially a problem, even in ranges not normally considered toxic. A Cochrane review of sixty-eight randomized trials of vitamin A supplementation (with a mean dose of 20,000 IU) showed an average of 16 percent increase mortality risk (mean three years).
¹³
This means that excess vitamin A is a risk for cancer, and that risk is significant.

There is also a major concern that supplemental vitamin A induces calcium loss in the urine, contributing to osteoporosis. Even though too much vitamin A is known to be toxic to the liver, the most common effect of toxic doses of vitamin A in animals is spontaneous fracture. Apparently, excess vitamin A is potentially a problem for human bones too
¹⁴
—one study showed a doubling of the hip fracture rate comparing vitamin A intake in the .5 milligram range to the 1.5 milligram range.
¹⁵
This is the 1,500 IU to 4,500 IU range, the typical amount found in most vitamin supplements. Vitamin A has also been linked to birth defects.

First, please note that
folate
is not the same thing as
folic acid,
though many people use these terms interchangeably. Folate is a member of the B vitamin family and is found naturally in plant foods, especially green vegetables. It is involved with DNA methylation, which essentially turns genes on and off. This critical role makes folate important in fetal development and nerve tissue health as well as cancer initiation and progression.

Due to folate's important role in DNA processing and human development, women are told to take folic acid in a prenatal supplement during pregnancy to prevent neural-tube birth defects. The problem is that folic acid is not the same as the folate found in real food. Folic acid is not found in natural foods at all; it is the synthetic form of folate that is used as an ingredient in vitamin supplements. Folic acid is also added to most enriched, refined grain products like bread, rice, and pasta in the United State and Canada, in an attempt to replace the nutrients lost during the processing of whole grains.

Because folic acid is added to so many refined grain products, it is very easy for a typical diet combined with a multivitamin to end up with high levels of folic acid. Too much folate obtained naturally from food is not a concern; only the synthetic form is suspect. Scientists do not yet know the implications of circulating synthetic folic acid, but more and more evidence suggests that supplementing with folic acid increases the occurrence of certain cancers.

Folate is abundant in all green vegetables. We do
not
need synthetic folic acid supplements to meet our daily folate requirements. Listed below are a few examples of folate-rich foods. (As a reference point, the U.S. RDI for folate is 400 micrograms.)

Recent studies have demonstrated significant concerns about folic acid:

• Women who took extra folic acid during pregnancy were followed by researchers for thirty years, and they were found to be twice as likely to die from breast cancer as women who had no folic acid supplementation.
¹⁶

• Another study following women for ten years concluded that those who took multivitamins containing folic acid increased their breast cancer risk by 20 to 30 percent.
¹⁷

• Folic acid supplementation by pregnant women has been associated with a higher incidence (in their offspring) of childhood asthma, infant respiratory tract infections, and cardiac birth defects.
¹⁸

• Men who took folic acid supplements for more than three years had a 35 percent increase in colorectal cancer risk, with increasing precancerous colorectal adenomas, according to a meta-analysis of several randomized controlled trials.
¹⁹

• In a ten-year study, folic acid supplementation was associated with more than double the risk of prostate cancer compared to placebos.
²⁰

• In two trials comparing folic acid supplements to placebos, overall cancer incidence and all-cause mortality were increased in the folic acid group over the nine-year study period.
²¹

• Recently, in Norway, where they do not fortify their flour with folic acid, researchers conducted a six-year study on the homocysteine-lowering effects of B vitamins for patients with heart disease. Unexpectedly, they found that those whose supplements contained folic acid were 43 percent more likely to die from cancer.
²²