Rarely do major diseases have a single cause. They are usually the result of a complex interaction between many factors, including genetic, environmental and lifestyle components. Many media reports, however, can lead us to believe that if we gave up something which we might otherwise enjoy, we could completely escape that particular affliction. Clearly, this is not the case. Non-smokers die of lung cancer.
Vegetarians die of cancer of the colon.
Tee-totallers die of liver complaints including cirrhosis. People who never go out in the sun contract skin melanomas. Always, there are other factors at work than the single element being examined in a scientific study. Quite often the alleged benefits of a particular nutritional element are the result not so much of the element itself but of the lifestyle and general diet of the people who consume it most. People who eat lots of healthy foods, including fibre, carrots, broccoli etc.