Is tea beneficial for cancer prevention?

Tea - Questions and Answers ABOUT FOODS AND CANCER PREVENTION AND SURVIVAL

QUESTION: Is tea beneficial for cancer prevention?

ANSWER: Perhaps. A recent study followed 69,000 Chinese women ages
forty to seventy and found that the more green tea consumed, the lower
the risk of developing colorectal cancer.33 The same effect has not been
found for oral cancer, gastric cancer, and perhaps for cancer in general.

However, it appears that there is a lower mortality rate among consumers
of regular green tea. Some have suggested that the health benefits
of green tea stem from the antioxidant properties of polyphenolic compounds,
or catechins, which are especially high in green tea due to its
unique preparation. Catechins can be found in many different types of
teas, not just green tea; however, the concentrations are inconsistent and
variable.

Catechins make up 30 percent of the weight of the dried green tea
leaves. It is known that antioxidant levels increase in the blood after green
tea consumption, but the implications of this for health are unclear. More
research is needed to understand green tea and its antioxidant activity in
the human body. However, some clinical trials investigating green tea consumption
by cancer patients found potential benefits that may prove
promising.34,35

Does drinking coffee or other caffeinated beverages increase cancer risk?

Caffeine - Questions and Answers ABOUT FOODS AND CANCER PREVENTION AND SURVIVAL

Caffeine

QUESTION: Does drinking coffee or other caffeinated beverages increase cancer risk?

ANSWER: Probably not. Interest in this topic persists because coffee is such
a popular beverage. In early 2006, a study suggested that coffee is responsible
for as much as one-third of daily consumption of the cancer-causing
chemical acrylamide, possibly as a result of the roasting of coffee beans.
Earlier studies linked coffee consumption to increased risks of bladder and
pancreatic cancers and a decreased risk of colon cancer.3 Subsequent studies
have not supported the link to pancreatic cancer. In addition, cigarettes
may be the real culprit in the link between coffee consumption and bladder
cancer, since smokers generally drink more coffee compared to the
average consumer.4 Studies on colon cancer, while mixed, lean toward a
possible protective effect from coffee.5

Regarding breast cancer, there is no evidence linking coffee consumption
to an increased risk. However, caffeine may increase symptoms of
fibrocystic breast disease, a common but benign breast condition.

According to a 2007 report by the American Institute for Cancer
Research, a part of the World Cancer Research Fund global network,
“Most evidence on coffee suggests that coffee drinking has no relationship
with cancer risk.”6

For bone health, heavy coffee use may be a problem. Excess caffeine
consumption causes calcium to be leached from bones and excreted in the
urine. Caffeine can also increase the heart rate, a concern in individuals
with certain types of cardiac arrhythmias.

How much alcohol is safe to consume?

Alcohol - Questions and Answers ABOUT FOODS AND CANCER PREVENTION AND SURVIVAL

Alcohol

QUESTION: How much alcohol is safe to consume?

ANSWER: Although we occasionally hear of the reputed benefits of moderate

alcohol consumption for reducing heart disease risk, even one drink per

day, if consumed every day, increases breast cancer risk.1 A recent review

of alcohol consumption and cancer risk also showed increased risk for

liver and colorectal cancer.2

Possible mechanisms by which alcohol may exert its cancer-causing

effects include the toxic effect of alcohol metabolites, the production of free

radicals, and disruption of folic acid’s protective mechanisms. Polycyclic

aromatic hydrocarbons, which are known carcinogens, have also been

found in alcoholic beverages. In addition, alcohol consumption may lead to

nutritional deficiencies, affecting the absorption of cancer-fighting nutrients.

Even one alcoholic drink per day, if consumed every day, increases breast cancer risk.

Soymilk, rice milk, almond milk, and oat milk - More Healthful Beverages

More Healthful Beverages - How Foods Fight Cancer

There is no shortage of better beverages. Soymilk, rice milk, almond milk,
and oat milk come in a wide variety of flavors and work very well on cereal
or for drinking. They are available in calcium-enriched and regular versions,
and many have additional vitamin fortification. Because a number of
these products require no refrigeration until they are opened (if they are
packaged in aseptic cartons), grocery stores sometimes stock them on the
dry goods shelves rather than in the refrigerated section.

milk’s fat & lactose content increase the risk cancer

Other Cancers - How Foods Fight Cancer

Researchers at Harvard University and elsewhere have also studied the links
between milk consumption and ovarian cancer, but with mixed results. The
hypotheses under scrutiny have related not only to milk’s fat content, but
also to its sugar, lactose.

Lactose is actually made of two smaller sugar molecules called galactose
and glucose. When these two sugars are split apart—either by the
bacteria used to produce yogurt or by digestive enzymes in your intestinal
tract—galactose and glucose enter the blood. Galactose may be the problem.

In large concentrations, galactose may be toxic to the ovaries,
encouraging infertility and possibly cancer. A recent analysis of studies
examining a relationship between dairy product consumption (skim, lowfat,
and whole milk, yogurt, cheese, and lactose) and ovarian cancer risk
found that for every 10 grams of lactose consumed (the amount in one glass
of milk), ovarian cancer risk increased by 13 percent among the prospective
cohort studies.9

Women with higher levels of IGF-1 in their blood have a greater risk
of premenopausal breast cancer. The Harvard Nurses’ Health Study found
that women with higher IGF-1 levels had more than double the risk compared
to women with lower IGF-1 levels.6 Other researchers have made
similar findings.10 As we’ve seen, milk drinking raises IGF-1 levels.

Other studies seeking to nail down the links between dairy consumption
and breast cancer risk have yielded mixed results, with some finding
higher risk of breast cancer among milk drinkers and others finding no
such association.

Foods that are high in calcium appear to reduce colon cancer risk.
However, people seeking ways to use calcium-rich foods to reduce colon
cancer risk would do well to get their calcium from green leafy vegetables
and beans rather than from dairy products. Prostate and breast cancer are
more common than colon cancer. Using dairy products to try to reduce
colon cancer risk may increase the risk of other, more common cancers.

Milk and Cancer Risk

Milk and Cancer Risk - How Foods Fight Cancer

Milk drinkers have more IGF-1 in their bloodstreams. IGF-1 is a powerful
stimulus for cancer cell growth.

To understand why dairy products might play a role in cancer, it helps to
remember their biological purpose. Milk is produced by mothers to support
the rapid growth of their newborns. It contains plenty of protein, fat,
and sugar (lactose), as well as dozens of hormones and other natural
chemical substances that direct infants’ growth and development. Milk
differs from species to species—cow’s milk is quite different in its nutrient
profile from human milk—but all mammals’ milk is designed to encourage
rapid growth.

After the age of weaning, of course, all mammals stop drinking their
mothers’ milk. A few thousand years ago, however, humans began to
domesticate animals and to consume milk taken from cows and a few
other mammals.

When humans drink cow’s milk, it causes some worrisome biological
changes in the body, one of which is a rise in the amount of insulin-like
growth factor 1 (IGF-1) in the bloodstream.3,4 IGF-1 is a powerful stimulus
for cancer cell growth. When breast cancer cells are mixed with IGF-1
in a test tube, for example, they grow rapidly.

Researchers have known for many years that men and women with higher levels of IGF-
1 in their blood are at higher risk for prostate and premenopausal breast cancer, respectively,
compared to those with lower levels.5,6 So one way that milk may influence cancer risk
is by increasing the amount of IGF-1 in the blood. Individuals who have been diagnosed
with cancer may be quite right to be concerned that milk drinking boosts IGF-1 levels in their
bloodstreams, given that IGF-1, in turn, can encourage cancer cell growth.

Milk causes other chemical changes in the body as well, some of which
relate to specific types of cancer. Generally speaking, these mechanisms relate
not only to the likelihood that cancer will strike, but also to how rapidly it
will grow and spread once it has occurred.