There are various studies examining cancers effects and preventions through diet and nutrition consisting of correlation studies, case-control studies, prospective cohort studies and meta-analysis studies. However, these various studies provide varied conclusions.
Albeit, the causing factors of cancer are surrounded by bad diet and malnutrition which cause over one third of U.S. cancer deaths. There is a strong link between cancer and to a high BMI due to a high level of energy intake. Mcardle et al (2006) associate a healthy balanced diet with reduced risk of cancer, one which consists of high in fibre, fruit and vegetable intake, low in red and processed meat, saturated fat, salt and alcohol intake. Longnecker (1994) also states that, “alcohol consumption increases endogenous oestrogen levels thus reducing intake of alcohol may reduce breast cancer”.
In opposition, fibre intake studies illustrating a reduction in colon cancer presented by cancer research UK; a large American study conducted by Mai et al (2003) looking at fibre’s relation to preventing colon cancer stated that, “fibre intake is not related to risk of colon cancer in older women at the lower end of the spectrum of intake levels”.
Nonetheless, Ames et al (1994) reiterates the aforementioned consumption of adequate fruit and vegetable intake that is associated with a lower risk of colon cancer, emphasising on the recommended five a day. Nevertheless, the antioxidants contained within fruit and vegetables are all unique, as a result, it is unlikely that all compounds sharing antioxidant properties would have similar effects against all types of cancer.
In addition, McCullough et al (2005) determined Vitamin D and calcium intake reduces the risk of colon cancer which reinforces Lipkins’ (1995) previous findings that “increased calcium antagonizes high-fat-induced proliferation thus reducing the risk of colon cancer”. Even so, Coulter et al (2006) concluded that, “multivitamin intake shows generally disappointing results”. Moreover, a prostate cancer study performed by Lawson et al (2007) concluded that, “the possibility of men taking high levels of multivitamins along with other supplements have increased risk of advanced and fatal cancers and merits further evaluation”.
Chronic infection and inflammation are said to contribute to one third of the world’s cancer. Viruses such as Hepatitis B and C can lead to liver cancer along with things such as asbestos exposure resulting in chronic inflammation and then leading to lung cancer.
Cancer research UK (cancerresearchuk.org.uk) illustrates that the prevalence of cancer cachexia is linked with malnutrition; however treatments come in various forms and if oral nutrition is possible adaptation of food intake along with modular products and sip feeding may be helpful. If this is not possible then tube feeding may take place along with pares oral nutrition.
Physical activity also plays an important role in the prevention of cancer with an evident link to high BMI, obesity and energy intake with little energy expenditure. Most widely studied is colorectal cancer and breast cancer.
Cancer research uk states that, “66-75% of colorectal cases could be avoided by changes of lifestyle”. However, physical inactivity shows otherwise and 50 studies on physical activity and colon cancer showed that there was an 80% decrease in risk in most physically active men and women. However, there was no association between physical activity and rectal cancer.
Another form of preventing colon cancer is to perform moderate physical activity as too much and you are at a greater risk of colon cancer if <4.2 MJ –week¯¹ (AEE) at intensity of 23-27 KJ¯¹.
Breast cancer has strong links to family history, diet, early menarche, late menopause, age at first childbirth, exposure to oestrogen’s and physical inactivity. Longnecker (1994) believes that exercise may lower breast cancer through influencing hormone levels and steadying cumulative oestrogen.
Physical activity also improves your immune function, allows for body fat reduction and releases metabolic hormones such as insulin and IGF-1. On the other hand, physical activity can disrupt the menstrual cycle which is not protective and also releases testosterone which increases the risk of prostate cancer (Ames et al 1994).
In conclusion, cancer incidence tracks patterns of behaviour and lifestyle habits. A healthy diet combined with moderate physical activity is among the biggest factors which should reduce the initiation, promotion and progression of some cancers. However, the contradicting views of many of the aforementioned statements clearly illustrate the need for further understanding.