Diet is strongly related to cancer

Specific components of the diet, as well as overall dietary patterns, play an important role in the development of cancer. There are hardly any studies that give us any clear answers to the role of diet/ nutrition in causing or preventing cancer. However, I have tried to analyze various studies and come up to this conclusion. The knowledge shared is purely based on the present evidence available.

1.     Dietary fat —

a.      The most extensively studied component of the diet is dietary fat. In the largest trial to examine this issue, the prospective Women's Health Initiative Dietary Modification Trial involving 48,835  women showed no difference in the incidence of colorectal cancer during 8.1 years of follow-up.

b.     A diet high in animal fat may be an important factor in the development of prostate cancer. In particular, the intake of large amounts of alpha-linoleic acid and low amounts of linoleic acid appears to increase risk; this combination is common in red meat and some dairy products

2.    Red meat —

a.     High intake of red meat has been associated with an increased risk of colon cancer. There have been studies identify carcinogenicity for processed meat.

b.     Red meat consumption has been associated with an increase in cancer  specific mortality.

c.     The mechanisms for this increased risk have not been determined, but several factors have been suggested including heme content in the meat, animal fat, and carcinogens produced when the meat is cooked at high temperatures.

3.    Fruits and vegetables —

a.     Though it might have been thought that a high intake of fruit and vegetables is associated with a significant reduction in cancer, numerous studies have found less consistent results. however, there is evidence to say that tomato products have some protective action in prostate cancer. Lycopene which is present in tomato is associated with a reduced incidence of prostate cancer.

b.     Increased flavonoids found in tomatoes, green peppers, berries, and citrus fruits have been associated with a modest decrease in breast cancer risk in Western populations.

4.     Dairy —

a.     There have been three prospective cohort studies did demonstrate an     increased risk of ovarian cancer with high intake of dairy foods. In Nurses Health study involving 88,000 women showed an inverse association between breast cancer risk and the intake of low-fat dairy products, calcium (mainly dairy intake), and vitamin D (mainly non-dairy intake) in premenopausal but not postmenopausal women

b.     Calcium intake is associated with decreased total cancer risk.

5.     Fiber —

a.     Fiber intake is associated with a reduction in the risk of heart disease and diabetes but its effect on cancer risk reduction is less certain. Though there is some role in Colon cancer prevention

b.     Several large cohort studies from the United States have not shown an   association between the development of colorectal adenomas or cancer risk and either fiber intake in general or cereal fiber in particular

6.     Glycemic load —

a.     Insulin and insulin-like growth factors promote cell proliferation, and it is hypothesized that hyperinsulinemia may promote certain cancers.

b.     Patients with diabetes have a twofold or greater risk of cancers of

c.     the liver

d.     pancreas

e.     endometrium

f.      colon

g.      breast

h.     bladder

However, the risk of prostate cancer is decreased in patients with diabetes

7.     Omega-3 fatty acids and dietary fish —

a.     Various prospective studies reveal no association between omega-3 fatty acids and cancer risk for 11 different types of cancer.However, there have been few observational studies showing fish consumption and a decreased incidence of colorectal cancer

8.     Caffeine —

California court ordered that caffeine to be labeled as a carcinogen in 2018, but till date, there is no data to suggest that coffee causes cancer, however, there is some thought process that the antioxidant property in tea and coffee actually prevent cancer.

a)    Breast cancer — The relationship between caffeine consumption and breast cancer is uncertain.

b)    Lung cancer — Meta-analyses suggest that caffeinated coffee is associated with an increased risk for lung cancer while decaffeinated coffee and green tea are associated with a decreased risk.

c)    Gastrointestinal cancer —

a.     Decreased risk of gastrointestinal cancers, particularly oropharyngeal and hepatic cancer

b.    Hepatocellular carcinoma –protective factor against liver cancer, including hepatocellular carcinoma.

d)    Endometrial cancer —

a.    No clear data

e)    Ovarian cancer — No clear data

f)      Bladder cancer — Previous studies examining caffeine consumption and     urinary tract cancers found a small increase in bladder cancer risk among   coffee drinkers

g)    Prostate cancer — Both coffee and green tea consumption are associated with a dose-dependent reduction in the risk of prostate cancer

9.    Dietary patterns —

a.    High intake of fruits, vegetables, nuts, legumes, whole wheat bread, fish, and olive oil was associated with a lower risk of cancer. There have been studies that show a lower percentage of patients with a vegetarian diet than for non-vegetarians to have cancer.

b.    "Western" diet including processed food, packaged snacks, frozen meals, sodas, instant soups, processed meats  were associated with greater than 10 percent increases in the risk of all-cancer and breast cancer

10. Vitamins and Micronutrients

A 2006 National Institutes of Health (NIH) consensus conference panel concluded that "present evidence is insufficient to recommend either for or against the use of multivitamin supplements by the American public to prevent chronic disease"

a.     Vitamin D — Overall, it does not appear that vitamin D supplements should be prescribed to decrease cancer risk

b.     Calcium — Increased calcium intake has been linked to a reduced risk of colorectal cancer but may be associated with an increased risk of prostate cancer. There may be a minimum level of calcium intake, around 700 mg/day, that confers protection against colorectal cancer without significantly increasing prostate cancer risk.

c.     Selenium — No beneficial effect of selenium on overall cancer mortality or incidence

d.     Vitamin E — May be harmful as per a few reports

e.     Folate and other B vitamins —

i.     Folate has been associated with a decreased risk for colon and other cancers, especially in individuals who consume alcohol, in observational studies. However, some randomized trials have suggested the possibility that folic acid may increase the risk for cancer.

f.      Iron — Observational studies suggest that increased iron stores or dietary iron may be associated with increased risk for cancer

11.  Alcohol

Excess alcohol consumption increases the risk of multiple cancers.

i.     10 g/day of alcohol (one drink) increased the risk for cancers

1.     Oropharynx

2.     Esophagus

3.      Larynx

4.     Rectum

5.      Liver

6.     breast

7.

The overall risk for cancer was increased 6 percent (95% CI 4 to 7 percent) for each 10 g/day of alcohol (of any type) consumed. The increased risk for cancers involving the upper respiratory and digestive tract was seen only in current smokers.