|LE Magazine January 2001 |
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Warding off cancer
More easily said than done, the ideal way to get all the essential nutrients would be to consume five to nine daily servings of fruits and vegetables, complemented by grains, low-fat foods and avoidance of animal source foods (i.e. meat).
More easily said than done, the ideal way to get all the essential nutrients would be to consume, as the American Cancer Society recommends, five to nine daily servings of fruits and vegetables, complemented by grains, low-fat foods and avoidance of animal source foods (i.e. meat). Since research is increasingly suggesting that predisposing factors to cancer development, whether environmental, dietary or otherwise, can set in early in life, it make sense to heed this advice starting in childhood. Findings that were recently presented at the American Institute of Cancer Research Annual Conference 2000 suggest, for example, that one's childhood diet may predict breast cancer risk later on in life more strongly than diet during adulthood. While still unclear, the evidence suggests that higher consumption of estrogenic foods in childhood lower one's breast cancer risk, perhaps by altering something in hormone receptors.
As for fruits and vegetables, their merit seems to lie in the fact that they pack a number of vitamins and minerals that may ward off cancer development by reducing oxidative damage in various body tissues. For example, there's strong evidence to recommend vitamin C as part of a preventive nutritional stance against esophageal, oral, stomach and pancreatic cancer, as well as mounting evidence that it protects against cervical, rectal and breast cancer.(16) Other research suggests that a higher intake of vitamins A, C and E and carotenoids in combination offers a protective effect against lung cancer.(17) Likewise, folic acid supplementation has been linked to a 50% decreased risk of colon cancer, possibly because of folate's ability to repair damaged DNA.(18) Cancer prevention is only one reason to ensure proper nutrient intake.
Meanwhile, research that has been examining how nutrition may affect the development of brain tumors in young children—the leading cause of death from childhood cancer—has found a strong link to maternal diet. One study, for example, found that high vegetable intake (and their respective nutrients) and vitamin and mineral supplementation during pregnancy significantly lowered the risk of tumor development.(19) In particular, those expectant mothers who consumed the most vegetables, fruits and fruit juices, vitamin A, vitamin C, nitrate (from vegetables) and folate had the greatest amount of protection for their unborn child. As well, taking iron, calcium and vitamin C supplements anytime during pregnancy and early multivitamin use (during the first six weeks) also were related to a decreased risk. Other research from the National Cancer Institute shows that women who took vitamins A, C, E and folate throughout their pregnancy cut in half the risk of having a child who developed a brain tumor before the age of 5. In fact, the study showed that the risk reduction was proportional to how long the women took the supplements.(20)
Numerous other studies likewise revealed an inverse correlation between prenatal multivitamin use and reduced risk of pediatric brain tumors. The dietary substance to be most incriminated for posing a possible risk of brain tumor development in young children has been nitrosamines and their precursors, nitrites and nitrates, which are found in cured meats. If their role is indeed to promote cancer growth, that might equally explain the preventive function of nutrients such as vitamins C and E, which are known to inhibit nitrosamines. The significance of this protective effect of nutrients in utero against tumors during infancy and early childhood suggests that it may be worthwhile to look at how nutrition throughout childhood may prevent other forms of cancer that strike in adulthood.
Building better immunity
Adequate nutrient intake from a well-rounded diet and supplementation forms a front-line defense against infectious diseases by fortifying the body's immune response system. The most well-touted nutrients include the antioxidants, vitamins, A, C, E and beta carotene, as well as minerals such as iron, zinc, folic acid and calcium. Research has shown that deficiencies in micronutrients such as zinc and vitamins A and D reduce natural killer cell function, whereas supplemental zinc and vitamin C enhance their activity.(21) A 1992 groundbreaking Canadian study, which looked at the effects of a 12-month daily multivitamin regimen on infection-related illness, uncovered that subjects taking the supplement showed “higher numbers of T-cell subsets and natural killer cells, enhanced proliferation response to mitogen, increased interleukin-2 production, and higher antibody response and natural killer cell activity.”(22) The supplement users were also sick less often with colds and flu—23 days of the year compared to 48 days among the controls.
Vitamin A, in particular, helps build resistance to respiratory infections. In fact, studies from countries where vitamin A deficiency is common have shown that levels of the nutrient greatly affect the outcome of infectious diseases such as measles and pneumonia. A study involving 180 children (median age 30 months) with measles in rural Tanzania found a reduction in mortality among children who received vitamin A supplementation in addition to routine treatment.(23) A South African study of children with severe measles complicated by pneumonia found that vitamin A helped them to recover more quickly than controls from pneumonia (6.3 days versus 12.4 days), and diarrhea (5.6 days versus 8.5 days). Children treated with vitamin A had less croup (13 versus 27 cases) and spent fewer days hospitalized (10.6 days versus14.8 days).(24)
Vitamin C, which is also known for immune-enhancing effects, has been shown to limit the symptoms of respiratory disorders such as asthma. In an Italian study of 18,737 children, ages six to seven, a higher intake of vitamin-C rich citrus and kiwi fruit diminished wheezing, shortness of breath, chronic and nocturnal cough, and non-coryzal rhinitis.(25)
Zinc is also known to be a key player in the immune system, as it aids in the development and function of neutrophils and natural killer cells. Zinc deficiency impedes the activity of macrophages, which compromise the roles played by cytokines and phagocytes.(26) According to a number of studies, zinc supplementation can increase resistance to infectious diseases such as pneumonia, diarrhea and malaria.(27)
Getting heart smart
Since heart disease takes years to develop, experts now suggest nutrition may be an integral part of early life intervention. After researchers examined the left heart coronary arteries from 760 autopsied men and women ages 15 to 34 (cause of death was an accident, homicide or suicide), they found that high blood cholesterol levels related to 2.5 times higher likelihood of advanced plaque blockages in their heart arteries compared to people with normal LDL levels.(28) Such findings, explained the investigators, provide “strong support to the idea that nutritional guidelines for the prevention of heart disease should be recommended for children as well as adults.”
For example, supplementation with folic acid, vitamins B6 and B12, can normalize homocysteine levels, found a University of Pennsylvania study. It suggested that “treatment with vitamin supplementation should be considered in all patients at risk for vascular disease.”(29) High blood levels of homocysteine are a predisposing factor for heart disease, and are present in about 20 million people in the US.(30) Folate intake has also been related to a drop in blood pressure readings. A study of urban minority adolescents at risk for hypertension found that mean diastolic blood pressure was significantly higher among youth with low-folate intake compared to those with a high intake.(31) The readings were about 8% higher among boys and 4% higher among girls with low-folate intake than in the controls. In addition, researchers found that the low-folate group also had significantly lower intakes of potassium, calcium, magnesium, beta carotene, cholecaciferol (vitamin D3), vitamin E and all B vitamins than the high-intake adolescents. The authors conclude that a diet rich in a combination of these lacking nutrients might contribute to primary prevention of hypertension when instituted at an early age.
Other heart-healthy nutrients are vitamins E and C, which studies have already shown to be beneficial for adults in reducing heart disease risk. For example, a large trial of 2002 patients showed that vitamin E could reduce non-fatal heart-attack risk by 77%.(32) A more recent study demonstrates that vitamin E might help to control, in children, the arterial damage that gradually leads to heart disease in adulthood.(33) California researchers gave subjects, ages 6 to 21, with an inherited tendency towards high blood lipid levels, 800 international units (IU) of natural vitamin E daily, plus 1000 milligrams of vitamin C daily, for six weeks. The combined regimen of vitamins E and C significantly increased blood vessel dilation, consequently improving endothelial function.
Meanwhile, L-carnitine, which has helped to treat cardiac failure patients, is now proving effective for treating cardiomyopathy in children.(34) Cardiomyopathy has many metabolic causes, and it can also result from carnitine deficiency. One study reported that serum-free carnitine levels in 24 children with heart failure were nearly 50% lower than those of 30 healthy controls.(35) Administering oral L-carnitine to the children with heart failure significantly improved their condition in less time than heart failure subjects who didn't receive oral L-carnitine.
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