With industrialisation has come a shift from traditional diets to the modern Western diet. Traditional diets are those eaten prior to complex food processing, and generally they contain high amounts of unprocessed and unrefined foods that maintain their original nutrient content. The typical Western diet in contrast is made up predominantly of processed and refined foods, the final product of which is largely different from the original raw ingredients. The refining and processing steps remove much of the fibre from plant foods as fibre can increase spoilage rates and is seen to detract from taste by the major food manufacturers. In addition, the refining process also removes many of the micronutrients. Addition of sugar and hydrogenated fats to the processing steps adds metabolic poisons to the final product. Refined and processed foods in the Western diet are therefore devoid of fibre and micronutrients, but contain high levels of metabolic poisons and this explains the association between consuming such a diet and the development of Western lifestyle diseases.
Care should be taken when assigning cause and effect from observational studies. However, taking this caveat into consideration, a large number of epidemiological studies have found associations between the consumption of plant foods and disease. For example, in one study1, researchers investigated the association between the consumption of fruits and vegetables and bladder cancer risk. The results showed that total fruit intake, total vegetable intake yellow-orange vegetables and citrus fruits were all associated with a reduced risk of bladder cancer in women. Analysis of the data showed that those women with the highest intakes of α-carotene, β-carotene, β-cryptoxanthin and folate had the lowest risk of bladder cancer. In men, fruits and vegetable intake was protective of bladder cancer amongst smokers. These results are therefore suggestive that the carotenoid content of fruits and vegetables might be particularly beneficial at preventing the development of certain cancers, as has been shown elsewhere.
However, increasing intakes of phytonutrients can be achieved without increasing the intake of fruits and vegetables and certain plant based beverages also contain high amounts of beneficial nutrients. Tea and coffee for example have been extensively researched for their beneficial health effects against cancer and cardiovascular disease. Observational studies have investigated the protective effects of tea and coffee and found that consumption is inversely associated with total mortality2. Each additional cup of coffee or tea per day conferred greater protective effects on mortality. Interestingly, coffee consumption was protective against non-vascular death, while tea was protective against vascular death. This suggests that consuming both coffee and tea would create a synergistic effect and reduce the risk of mortality further. Tea and coffee contain a number of phytonutrients including polyphenols that may have antioxidant effects. However, caffeine may also play a role in the protective effects from disease, particularly against dementia.
Dr Robert Barrington’s Nutritional Recommendation: Plant foods should be a major part of every healthy diet. The evidence that unrefined plant foods in their original plant material form are beneficial to the health is now very strong. In particular plant foods are protective of the Western lifestyle diseases including cardiovascular disease, cancer, obesity and type 2 diabetes.
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