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  1.   The two main omega-3 fatty acids are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). It has been generally accepted that fish and sea foods are the best sources of omega-3 fatty acids and should be consumed 2-3 times a week, as these compounds have been suggested to reduce the risk of cardiovascular disease.[1] The main source of these omega-3 fatty acids is oily fish such as salmon, mackerel and sardines. Olive oil and some seeds and nuts such as flax seeds, chia seeds, walnuts and pumpkin seeds are also rich in alpha-linolenic acid (ALA), another omega-3 fatty acid, which the body can then convert to DHA or EPA however to a limited extent of 2-10%.[2] The perceived benefits of omega-3 fatty acids originated from the observation of Japanese and Mediterranean populations. Japanese and Mediterranean consumption of fish is high while Mediterranean diet also encourages the use of olive oil. These populations have a lower incidence of cardiovascular disease and consequently a tendency to live longer.[3]  In addition to being associated with healthier cardiac function, studies have shown omega-3 fatty acids also play a role in healthy ageing and foetal development.[2] In fact studies have demonstrated that the many beneficial attributes of omega-3 fatty acids include reduced incidence of atherosclerosis and reduced inflammation in both overweight sedentary adults and healthy older adults.[4] [5] Furthermore animal studies have also demonstrated that an increase in omega-3 fatty acid intake can reduce the risks of Alzheimer’s disease.[6] Omega-3 supplements have also been linked to a reduction of the risk of prostate cancer. [7] Despite these potentially obvious positive effects, recent evidence has emerged that questions the benefits of omega-3 fatty acids obtained from either consumption of fish or supplements.[1] Recent studies have highlighted that increased omega-3 fatty acid consumption in people already at risk of heart disease does not reduce the incidence of stroke, heart attack or death.[8] Another study also demonstrated that omega-3 fatty acids have no discernible impact on overall mortality or the incidence of cardiovascular disease or cancer.[9]  Furthermore, contrary to some studies, high levels of omega-3 fatty acids in the blood have actually been correlated with an increased risk of prostate cancer.[10] These recent findings have led some to believe that omega-3 fatty acid supplementation may actually be harmful to the body during several medical conditions. This theory comes from the fact that, like all fatty acids, omega-3 fatty acids are prone to lipid peroxidation. Lipid peroxidation is oxidative degradation of lipids, mostly of unsaturated fatty acids making up triglycerides and phospholipids. Consumption of oxidised lipids can result in increased oxidative stress, which is associated with many adverse health effects. Indeed prolonged high levels of oxidised lipids in the blood can lead to atherosclerosis.[11] [12]  Oily fish may also contain persistent organic pollutants or metals, the latter of which may facilitate the lipid peroxidation described above.[1] Furthermore, it has also been suggested that, as omega-3 supplements lack the range of nutrients such as proteins, vitamins and minerals present in whole fish, their efficacy and function may be compromised.[13] When speaking about omega-3 fatty acids consumption the issue of omega-3 to omega-6 fatty acids ratio has to be also taken into account. With the evolution and development of agriculture this ratio has shifted from 1:1 to about 1:15 which is thought to be one of the reasons for increased incidence of heart diseases and obesity. However the optimal ratio is not yet defined according to the UK Food Standards Agency and it is advised to increase the intake of omega-3 rather than focuse on decreasing the amount of omega-6 fatty acids in your diet.[14]   Omega-3 fatty acids are essential fatty acids that play a crucial role in maintaining good health. As our bodies cannot produce them, we need to obtain them from dietary sources such as oily fish and plant oils. Given the potential for reduced efficacy when eaten in its pure form, omega-3 consumption through the diet is preferable to taking omega-3 nutritional supplements. Remember to use mild temperature ways of cooking for omega-3 rich foods to avoid lipid oxidation and preserve the benefit of omega-3. Whilst some of the health benefits previously attributed to omega fatty acids may now be under scrutiny, it is apparent it may be more to do with omega-3 to omega-6 ratios than doubting omega-3 benefits and so it is still a key part of a healthy diet and potential benefits appear to outweigh the potential risks.    [1] Maehre H, et al. (2016). ω-3 Fattyω-3 Fatty Acids and Cardiovascular Diseases: Effects, Mechanisms and Dietary Relevance Acids and Cardiovascular Diseases: Effects, Mechanisms and Dietary Relevance. International Journal of Molecular Sciences, 16(9), 22636- 22661. https://dx.doi.org/10.3390%2Fijms160922636 [2]  Swanson, D. (2012). Omega-3 fatty acids EPA and DHA: health benefits throughout life. Advances in Nutrition, 3(1), 1-7. https://doi.org/10.3945/an.111.000893 [3] Tokudome, S., et al (2004). The Mediterranean vs the Japanese diet. European Journal Of Clinical Nutrition, 58, 1323. http://dx.doi.org/10.1038/sj.ejcn.1601970 [4] Sekikawa A, et al. (2008). Marine-derived n-3 fatty acids and atherosclerosis in Japanese, Japanese Americans, and Whites: a cross-sectional study. Journal of the American College of Cardiology, 52(6), 417-424. https://doi.org/10.1016/j.jacc.2008.03.047 [5] Kiecolt-glaser, J.K. (2012). Omega-3 Supplementation Lowers Inflammation in Healthy Middle-Aged and Older Adults: A Randomized Controlled Trial. Brain, Behavior, and Immunity, 26(6), 998-995. https://doi.org/10.1016/j.bbi.2012.05.011 [6] Lim G.P, et al. (2005). A diet enriched with the omega-3 fatty acid docosahexaenoic acid reduces amyloid burden in an aged Alzheimer mouse model. The Journal of Neuroscience, 25(12), 3032-3040. https://doi.org/10.1523/JNEUROSCI.4225-04.2005 [7] Augustsson K, et al.(2003). A Prospective Study of Intake of Fish and Marine Fatty Acids and Prostate Cancer. American Association for Cancer Research, 12(1), 64-67. http://cebp.aacrjournals.org/content/12/1/64 [8]  The risk and prevention study collaborative group. (2013). N–3 Fatty Acids in Patients with Multiple Cardiovascular Risk Factors. The New England Journal of Medicine, 368(1), 1800-1808. https://doi.org/10.1056/NEJMoa1205409 [9] Hooper, L. et al. (2006). Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ, 332(752) https://doi.org/10.1136/bmj.38755.366331.2F [10] Brasky, TM. et al. (2013). Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial. Journal of the National Cancer Institute, 105(15), 1132-1141. https://doi.org/10.1093/jnci/djt174 [11]  Awada M, et al. (2012). Dietary oxidized n-3 PUFA induce oxidative stress and inflammation: role of intestinal absorption of 4-HHE and reactivity in intestinal cells. Journal of Lipid Research, 53(10), 2069-2080. https://doi.org/10.1194/jlr.M026179 [12] Lobo V, et al. (2010). Free radicals, antioxidants and functional foods: Impact on human health. Pharmacognosy Review, 4(8), 118-126. https://doi.org/10.4103/0973-7847.70902 [13]  He, K. (2009). Fish, Long-Chain Omega-3 Polyunsaturated Fatty Acids and Prevention of Cardiovascular Disease—Eat Fish or Take Fish Oil Supplement? Progress in Cardiovascular Diseases, 52(2), 95-114. https://doi.org/10.1016/j.pcad.2009.06.003 [14] Stanley, J., Elsom, R., Calder, P., Griffin, B., Harris, W., & Jebb, S. et al. (2007). UK Food Standards Agency Workshop Report: the effects of the dietary n-6:n-3 fatty acid ratio on cardiovascular health. British Journal Of Nutrition, 98(06). http://dx.doi.org/10.1017/s000711450784284x
  2. Drug interactions occur when the effect of a drug is altered if taken in conjunction with another drug, supplement, food, or alcohol. Drugs can interact with dietary supplements either directly or indirectly, increasing or decreasing the drug’s desired effects. Indirect effects can result from changes in excretion,  metabolism or, occasionally, absorption of the substance, which can result in reduced or increased pharmacological activity of the drug. This can trigger unexpected and potentially harmful side effects. These interactions can occur in numerous ways, from the way different substances react with each other in the stomach, to the mechanism of metabolism in the body. Such interactions can vary between subjects, as everyone’s body is different in terms of its ability to absorb, metabolise, distribute and excrete drugs and their metabolites. There are several factors that can lead to these differences, including genetic variation, body weight (hence why some drugs are dosed according to this), age, gender (often due to hormone levels), drug tolerance and even diet. An example of the latter is the reduced response to bronchodilators associated with a high-fat diet.[1] Because of these variations, drug interactions can be difficult to predict, even when their reactions are well-known.  Western populations consume an ever-increasing amount of dietary supplements, including vitamins, minerals, herbs and many other products. These can come in many forms, such as pills, capsules, powders, drinks and energy bars. Adverse reactions between supplements and prescribed medications are well documented: warfarin, insulin and aspirin, for instance, have a high record of adverse interactions with dietary or herbal supplements.[2] Mixing warfarin and fish oil, for example, can lead to uncontrolled bleeding, while insulin combined with chromium can induce hypoglycaemia in diabetics.[2] The increasing number of dietary supplements available, coupled with the fact that they are not as well-regulated as medicinal products, means the potential for adverse interactions is escalating. Consumers tend to assume that because dietary supplements are so readily available, they must be safe – a belief enhanced by the liberal use of the word ‘natural’ in association with these products. However, their safety is not necessarily assured, and their combined use with certain drugs can result in serious adverse reactions. Commonly used supplements such as vitamin E, ginseng and gingko biloba have all been touted for their ability to boost certain health aspects, but they also interact with various widely prescribed drugs, causing life-threatening reactions such as reduced blood clotting, psychosis, hypoglycaemia and even coma.[2] It is not just adverse reactions that are of concern when combining supplements and drugs. Interactions can also reduce a drug’s effectiveness, such as the interaction seen between St. John’s wort and oral contraceptive pills.[3] Consumers should always think carefully when choosing dietary supplements, especially those who are taking medications. The combination could potentially be lethal – a far cry from the aim of trying to improve your health. Always consult your doctor before taking a supplement or changing your medication regimen.   [1] Wood LG, Garg ML, Gibson PG (2011). A high-fat challenge increases airway inflammation and impairs bronchodilator recovery in asthma. J Allergy Clin Immunol. 127(5). 1133-40. [2] Gardiner P, Phillips R, Shaughnessy AF (2008). Herbal and dietary supplement-drug interactions in patients with chronic illnesses. Am Fam Physician. 77(1). 73-8. [3] Murphy PA, Kern SE, Stanczyk FZ, Westhoff CL (2005). Interaction of St. John's Wort with oral contraceptives: effects on the pharmacokinetics of norethindrone and ethinyl estradiol, ovarian activity and breakthrough bleeding. Contraception. 71(6). 402-8.