Leafy Greens May Boost Men's Bowel Cancer Risk Study Says

A new study warns that eating specific leafy greens might boost your risk of bowel cancer by half, but only for men. Researchers found that gulping down large amounts of nitrites present in rocket and Swiss chard could push those odds up significantly. It has long been accepted that these chemicals fuel the growth of tumors in the gut. The World Health Organisation classifies nitrites as Group 1 carcinogens, placing them right alongside tobacco and asbestos on the danger list. Most attention usually falls on nitrites added to processed meats to keep them pink and fresh longer. Those additives react with meat proteins to create nitrosamines, which then transform healthy bowel cells into cancerous ones. Now scientists claim the food source of these nitrites matters far less than experts once believed. Bowel cancer cases have skyrocketed recently, leaving more than 48,000 victims diagnosed in the UK each year.

Bowel cancer has overtaken other killers to become the leading cause of death for people under 50. Experts are sounding the alarm, warning that a failure to ban nitrites found in bacon and ham could have already cost thousands of lives. A fresh study published in the Journal of the National Cancer Institute sheds light on this crisis. Researchers analyzed the diets of 82,009 middle-aged Swedish adults who filled out food questionnaires back in 1997, 2009, and 2019. Anyone with a prior cancer diagnosis was left out of the study, except for non-melanoma skin cancer cases.

The team combined data from the Swedish Food Agency with their own nitrite measurements taken from hundreds of foods to calculate average daily intake. The numbers reveal that meat products made up just over half of men's nitrite consumption, while processed meats contributed roughly a quarter. Around 20 per cent came from vegetables, cheese, and other dairy goods. Over the twenty-year follow-up, 3,170 participants received a colorectal cancer diagnosis. More cases showed up in men. Those with the highest nitrite intake were 23 per cent more likely to be diagnosed with bowel cancer than those at the low end of the scale. Interestingly, no significant link appeared in women.

After factoring in fibre intake, which helps protect against the disease, as well as age, family history, weight, and smoking status, the researchers concluded that a diet heavy in nitrites raises risk for men regardless of where the food comes from. The association was strongest for cancer affecting the lower part of the bowel. Men consuming the most nitrites faced a 50 per cent increased risk. One theory suggests this section of the organ might be especially vulnerable to harmful compounds formed when nitrites break down during digestion. Previous studies found higher levels of DNA damage linked to these compounds in that specific area. However, the researchers noted more work is needed to confirm this finding.

Right now, up to 90 per cent of bacon sold in the UK contains nitrites, which have been tied not only to bowel cancer but also breast and prostate cancers. NHS guidelines advise limiting processed meat to no more than 70g a day, that's around two rashers of bacon. Red meat has also been flagged by health officials as probably carcinogenic. Yet another twist emerged from the biggest study yet on meat-free diets, published in February. It highlighted a new warning: vegans face a 40 per cent higher risk of bowel cancer than meat-eaters. Researchers from the University of Oxford said these findings underline that cutting out meat brings benefits but is not risk-free because other food sources contain potentially harmful nitrites.

Bowel cancer ranks as the fourth most common cancer in the UK and sits as the second biggest cause of cancer deaths, claiming more than 17,000 lives every year. Symptoms include changes in bowel habits like persistent diarrhoea or constipation, a feeling of incomplete emptying, and blood in the stool. Stomach pain, bloating, unexpected weight loss, and fatigue are other warning signs. This news arrives as a major global analysis across 42 countries found that bowel cancer is the only cancer rising exclusively among under-50s. In England, diagnoses among 25 to 49-year-olds have jumped by more than 50 per cent since the early 1990s. Cancer Research UK estimates that more than half of bowel cancer cases in Britain are preventable. What can we do about it?