287 Virgin Olive Oil Benefits Although their lifestyle (climate, physical activity, etc.) and their very specific and limited diet (based mainly on meat, fish, seal, and whale fat -usually raw-) are not directly comparable to those of Western populations, this observation led to the hypothesis that these fats could exert beneficial effects on the health of these Western populations. Since then, research has explored their potential protective role, particularly in cardiovascular health, as well as in cancer, hypertension, diabetes, and inflammatory bowel disease. Regarding cardiovascular health, research has focused primarily on long-chain omega-3 polyunsaturated lipids (ω-3). In this regard, epidemiological studies consistently report a reduction in cardiovascular events associated with the consumption of fish and fish oils rich in EPA and DHA. However, the results from clinical trials and their meta-analyses are contradictory. In addition, there is clear evidence of a dose-dependent beneficial effect of long-chain omega-3 polyunsaturated fatty acids (ω-3) on hypertriglyceridaemia (elevated blood triglyceride levels), a modest blood pressure-lowering effect, and possible positive effects on heart rhythm. On the other hand, neither dietary intake nor supplementation with ω-3 polyunsaturated fats appears to protect against the risk or development of diabetes. The effects of ω-3 lipids on cancer have been extensively studied. Overall, omega-3 polyunsaturated fats (ω-3) are considered to exert beneficial effects, particularly on types of cancer commonly found in Western countries, such as breast, colon, and prostate cancer. These fatty acids have shown anti-tumour properties in both “in vitro” (cell cultures) and animal models. Some studies suggest that their effects may be explained by changes in membrane phospholipid composition, which affect membrane fluidity, alterations in eicosanoid metabolism, the promotion of tumour cell death by apoptosis, and the reduction of metastasis. However, evidence in humans is not always so clear. Most of the available data comes from epidemiological studies, and not all of these have shown significant associations between the intake of long-chain omega-3 fatty acids (ω-3) or fish consumption and reduced risk of breast, prostate, or colorectal cancer. Nevertheless, when these studies involve large populations or are included in meta-analyses that combine multiple studies, clear benefits of omega-3 (ω-3) fats emerge. One such example is the EPIC study (“European Prospective Investigation into Cancer and Nutrition”), coordinated by the WHO’s International Agency for Research on Cancer. With 519,978 participants (of whom 366,521 were women), it is the largest multicentre prospective epidemiological study carried out to date. It found that higher consumption of oily fish was associated with a lower risk of breast cancer, and that adherence to the Mediterranean diet was protective against both breast and colorectal cancer. Nonetheless, both the EPIC study and the global review conducted by the “World Cancer Research Fund (WCRF)” concluded that total fat consumption, when excessive, shows the strongest association with overall cancer risk. As with other diseases, the potential health benefits of these fats are only seen when consumed in moderation. As previously mentioned, fats are the most energy-dense nutrients (9 kilocalories per gram), and cancer cells are extremely active, with very high energy requirements. For this reason, any type of fat consumed in excess may provide the energy supply that fuels tumour development. Conversely, caloric restriction has been
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