According to a World Health Organization (WHO) report, processed meats – such as bacon, hot dogs, sausages and ham – do cause cancer.
The WHO’s report said 50g of processed meat a day – less than two slices of bacon – increased the chance of developing colorectal cancer by 18%.
Meanwhile, the health agency said red meats were “probably carcinogenic” but there was limited evidence.
The WHO did stress that meat also had health benefits.
Processed meat is meat that has been modified to increase its shelf-life or alter its taste – such as by smoking, curing or adding salt or preservatives.
It is these additions which could be increasing the risk of cancer. High temperature cooking, such as on a barbeque, can also create carcinogenic chemicals.
The WHO has come to the conclusion on the advice of its International Agency for Research on Cancer, which assesses the best available scientific evidence.
The International Agency for Research has now placed processed meat in the same category as plutonium, but also alcohol as they definitely do cause cancer.
However, this does not mean they are equally dangerous. A bacon sandwich is not as bad as smoking.
“For an individual, the risk of developing colorectal [bowel] cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed,” Dr. Kurt Straif from the WHO said.
Estimates suggest 34,000 deaths from cancer every year could be down to diets high in processed meat.
That is in contrast to one million deaths from cancer caused by smoking and 600,000 attributed to alcohol each year.
Red meat does have nutritional value too and is a major source of iron, zinc and vitamin B12.
However, the WHO said there was limited evidence that 100g of red meat a day increased the risk of cancer by 17%.
The WHO said its findings were important for helping countries give balanced dietary advice.
A new study suggests that teenage obesity is linked to a greater risk of bowel cancer later in life.
The study, published in the journal Gut, followed 239,658 Swedish men for 35 years. The young men were conscripted into the military aged 16 to 20 years old.
The analysis, led by Orebro University Hospital in Sweden and Harvard University, showed overweight teenagers went on to have twice the risk of bowel cancer. The figures were even higher in obese teens.
Teenage boys who become very obese may double their risk of getting bowel cancer by the time they are in their 50s.
The study and researchers were funded by the National Cancer Institute, Harvard School of Public Health, Örebro University and the UK Economic and Social Research Council (ESRC).
The World Cancer Research Fund said the link between obesity and cancer was “strong”.
Bowel cancer is the third most common cancer in the world, with nearly 1.4 million new cases each year.
Processed red meat and abdominal fat have been linked to the disease.
The overwhelming majority of participants were a normal weight, but 6.5% were overweight and 1% were obese.
There were 855 cases of colorectal cancer in the study.
However, the results showed not all weights were affected equally.
Those who were obese were 2.38 times more likely to have developed a bowel tumor.
The study said: “Late adolescence marks the transition from childhood to adulthood and is a period of accelerated growth, especially among men, thus this period may represent a critical window.
“It is important that we understand the role of exposures in childhood and adolescence in the development of colorectal cancer.
“In fact, the strong association observed between adolescent obesity and early-to-mid-life colorectal cancer [CRC], coupled with the increasing prevalence of adolescent obesity, may shed light on the increase in colorectal cancer incidence among young adults.”
Being obese and having long-lasting (chronic) signs of inflammation in the body as an adult have been linked to increased bowel cancer risk. Adolescents with “high” levels of inflammation were more likely to develop bowel cancer than those with “low” levels.
The marker (or sign) of inflammation the researchers had information on was the erythrocyte (red blood cell) sedimentation rate, or ESR. This measurement increases when there is inflammation.
However, few of the studies have assessed the effect of obesity in adolescence specifically, and none have been said to look at the impact of inflammation in adolescence.
The researchers concluded that, “late-adolescent BMI and inflammation, as measured by ESR, may be independently associated with future CRC risk”.