In honour of Junk Free June, which is being supported by the Cancer Society, it seems timely to talk about the relationship between the food we eat, the cancers we get, and what can be done to reduce the cancer burden in our society.
What is the relationship between food and cancer?
It is estimated that 30% of cancers in the developed world are due to lifestyle issues (so what we eat, drink, how fat we are and how much we exercise), and are therefore preventable.
What does this 30% ‘preventable cancer’ figure mean in terms of cancer in NZ?[box type=”alert” size=”large”]If we all ate a bit better, got more exercise and were able to maintain a healthy weight, then each year 6946 fewer people would get cancer (that’s the entire population of Te Puke – the heart of kiwifruit country!).[/box]
In New Zealand in 2011 (the latest data we have), there were 21,050 new cases of cancer diagnosed. Cancer is our number one cause of death (in 2011, 8891 people died from cancer).
The most common cancer is New Zealand is colorectal cancer, the next are breast and melanoma. The cancer that causes the most deaths in NZ is lung cancer (mainly because there are no signs or symptoms of this cancer until it is quite advanced so it is hard to treat), followed by colorectal cancer (this causes a lot of deaths because a lot of people get it).
While clearly smoking is a big factor in lung cancer (50% of people who smoke will get lung cancer), colorectal cancer (cancers found anywhere on the lower intestinal track) has a particularly strong relationship with our lifestyle and what we eat and drink.
Let’s talk Sausage
While there was a lot of talk for years from scientists about the relationship between eating red meat and colorectal cancer, more recently the relationship found between meat and cancer is thought to be a more specific one. It is the relationship between eating processed meats and cancer that is concerning. Processed meat is meat that has been cured or salted or preserved. We are talking here about salami, bacon, sausage, black pudding, chorizo, pastrami etc but NOT fresh red meat like mince. A recent high quality European trial has shown that those that eat a large amount of processed meats (those that eat 160gms of the stuff a day – that is a cup of chopped salami!) have an 11% increased risk of death from cancer. The research went on to estimate that 3.3% of deaths could be prevented if all participants had eaten less than 20grams a day of processed meat (a rasher of bacon or a slice of ham)
Why is it that the processed meats are so bad?
The current thinking is (although this has yet to be proven) that the nitrates that are used in the processing of these meats go through a process in our bodies which turns them into a cancer causing (carcinogenic) substance.
The World Cancer Research Fund advises avoiding processed meat altogether. Yet for many who eat western diets this is a challenge (I LOVE a really good bit of ham personally). So the no risk approach is to go cold turkey (no pun here!), however if you can’t, only eating a small amount of it significantly reduces your risk.. Let’s face it, processed meats are a salty fatty food and lots of that is never going to be good, so cutting down on that where you can is a positive thing.
Fruit & Veges
Fruit and vegetables are often talked about in the context of cancer. In the early days of the 5 plus campaign (you know – eat two fruit and three vege a day), the focus was on the protective effect that the micronutrients (especially antioxidants) in fruit and vege have against cancer – they are cancer fighters. However, more recently the focus is on their role in obesity prevention. Eating lots fruit and vegetables and other ‘whole foods’ (those foods that are in their ‘as they were made state’, have a lot of fibre and nothing else added to them) help maintain a healthy body weight when they replace other foods high in sugar, fat and energy.
Alcohol is also strongly linked to cancer development, some of that relationship is due specifically to the ethanol in alcohol.
This from the Cancer Society “our body breaks ethanol down into smaller substances that are absorbed into our blood stream. One of these substances is called acetaldehyde. Acetaldehyde can bond with our DNA (the genetic information in every cell) to increase the risk of cell mutations (damage to cells) and disrupts normal cell replication (how cells normally copy themselves) which may increase the risk of cancer.”
Importantly however, alcoholic drinks are very ‘calorie rich’ and ‘nutrient free’, so consuming booze frequently and/or in large amounts also contributes to too much body fat (which we will talk about in the next blog). So what is a low risk approach to booze?
The Health Promotion Agency’s (HPA) advises that low risk drinking is no more than:
- two standard drinks a day for women and no more than 10 standard drinks per week.
- three standard drinks a day for men and no more than 15 standard drinks per week.
A standard unit depends on the alcohol content of what you are drinking, wine is about 100ml, beer 350ml, and spirits 30 ml.
A couple of alcohol free days a week is also a good idea.
The Other Nasties (and some Goodies too)
There are other groups of foods that MAY increase or decrease a person’s risk of certain cancers
- Too much salt may increase your risk of stomach cancer
- A diet high in saturated fat may increase your risk of Breast cancer.
- High fish consumption may lower bowel cancer risk, as will a high fibre diet.
And if you are interested is other food controversies and cancer, have a read of the trustworthy Cancer Research UK’s take on the evidence relating to things like acrylamides, artificial sweeteners, green tea, superfoods and more.
However, all this is really a diversion from the BIG problem with cancer and food. It is less about the specific foods we eat and more with how much we eat and how fat we get from it. We will talk about this in the next blog.