New Under the Sun:
Volume 3, Issue 7
We are now entering the second half of the year. This is a good point to pause and reflect on where you are and what you need to do in order to optimize health and well being. Is your diet adequate in antioxidant-rich fruits and vegetables? Are you including tree nuts such as walnuts and almonds? Are you getting enough exercise through walking and swimming? Are you sleeping 8 – 10 hours each night? Are you getting enough vitamin D? If not, it is time to make the necessary modifications. If you are doing well, congratulations, and keep up the good work!
Safe Fish Consumption: As has been mentioned frequently in AnthroHealth News, fish should be an important component of your diet. However, there is concern related to the build up of toxins in certain varieties of fish, particularly the fatty, oily types. Since these types of fish provide needed omega 3 fatty acids along with large quantities of vitamin D, it is especially important to balance the healthful benefits with the potential toxic harm. Recent research from Britain details the best, safest fish to eat, and appropriate quantities of fish to eat for different groups such as pregnant women.
The overall recommendation of the Scientific Advisory Committee on Nutrition (SACN) is that the average person can eat and needs to eat more servings of fish each week. Currently, the average in Britain is about 1/3 serving of fish each week. The SACN recommends at least two servings per week. Although white fish provide a quality, low fat source of protein, the real benefits from eating fish come from the fatty acids in fatty fish such as salmon, sardines, mackerel, trout, and herring. These fatty acids have been shown to improve heart health and play an important role in the neurological development of the fetus and infant. In addition, fatty fish are the best food source of vitamin D. Therefore, it is not enough to simply eat more fish. The increased consumption needs to include more servings of fatty fish.
However, as mentioned, toxins are a concern. Methylmercury builds up in the tissues of all types of fish, white or oily. The amount of this toxin in particular species of fish is related to their position in the food chain. Those at the low end have the lowest levels while those at the high end, the predatory species, have the highest levels of methylmercury. Given this, the SACN recommends that pregnant women or women planning to become pregnant avoid eating large fish such as shark, swordfish, and marlin. Since this toxin adversely affects development, they also recommend that children under 16 avoid eating these fish. Everyone else can eat up to one serving each week. Although tuna is a large fish, the level of methylmercury in tuna is lower than in the fish listed above. Therefore, SACN considers it safe for pregnant women to eat two tuna steaks or four medium-sized cans of tuna each week. The amount of tuna other adults and children can eat is unrestricted.
Dioxins are a particular problem for fatty fish since they accumulate in the fatty tissues. They also accumulate in the fatty tissues of humans who eat the fish. The long half-life of dioxins is the reason they present concerns to human health. The main problems with dioxins seem to be: 1) negative impact on male reproductive development caused by the mother’s high levels of dioxins during gestation; 2) increased cancer risk. Despite these problems, dioxins are less of a health concern than is methylmercury. Therefore, even girls and women during their reproductive years can eat (based on their body weight) up to two servings of fatty fish each week while everyone else can eat up to four servings.
Much more information on this topic can be found at the SACN website of their report on fish consumption: http://www.food.gov.uk The site includes a chart that summarizes the main conclusions concerning oily fish consumption: http://www.food.gov.uk/news/newsarchive/2004/jun/fishportionslifestagechart
Fifty Years of Smoking: Once again we turn to Britain for news, this time of the results of a landmark study on smoking begun in 1951 which followed the lives and health of over 34,000 male physicians through 2001. The initial results on smoking and health were published in 1954. The most recent results on the original study subjects have just been published this year. One of the authors of the original report, Richard Doll, is still alive and is a co-author of the current report. Given the results of this report, it is probable that Dr. Doll either was never a smoker, or quit smoking quite some time ago.
In 1951, smoking was quite common, especially among veterans of World War II who had received cigarettes as part of their rations. There was concern that smoking had an adverse effect on health, particularly increased rates of lung cancer, but this study would be the first major prospective study to look at the effects of smoking over a long period of time on a large number of individuals. Physicians were chosen as the study population primarily because licensing requirements would make it easy for the research team to find and contact the individuals or obtain their death certificates during the intervening fifty years. Interim studies published in 1957, 1966, 1971, 1978, and 1991 found that although smoking was associated with increased rates of lung cancer, less than 50% of the higher mortality rates of smokers compared to nonsmokers resulted from lung cancer. Heart disease and other diseases were factors in the majority of excess mortality cases.
Number of years one smokes and number of cigarettes smoked each day are significantly and linearly associated with risk of premature death. That is, those who smoke the most and the longest have the most years (an average of ten years) cut from their life expectancy. The earlier in life one ceases to smoke, the fewer the years cut from one’s life expectancy. If an individual quits smoking at age 30, there is no reduction in life expectancy. An individual you quits smoking at age 60 reduces his life expectancy by seven years. Heavy smokers have about three times the probability of early mortality over non-smokers.
The authors conclude that if current worldwide smoking rates continue, the 21st century will come to a close with about one billion individuals having died prematurely from smoking-related causes. Richard Doll, Richard Peto, Jillian Boreham, Isabelle Sutherland. Mortality in relation to smoking: 50 years' observations on male British doctors. BMJ 2004;328:1519 (26 June), doi:10.1136/bmj.38142.554479.AE (published 22 June 2004)
Comment: The finding from this study that increased rates of heart disease are associated with smoking provides additional support for the study presented in the May, 2004 issue of AnthroHealth tying a drop in deaths from heart attacks to the institution of a city-wide smoking ban.
Frequent Dieting and the Immune System: Obesity is a major risk factor to optimal health since it is associated with increased heart disease and type 2 diabetes. Weight loss can lead to significant improvements in health. However, inappropriate weight loss and/or frequent episodes of weight loss and regain, can also have a negative impact on health. Major changes and stressors can depress the immune system. Weight loss can be both an important change in body mass and a stressor, therefore it should not be surprising that it could have an impact on the immune system. In order to clarify the connection, researchers examined immune system function in 114 postmenopausal women who were overweight and sedentary, but who were basically healthy. Information on prior episodes of dieting and weight loss were obtained from questionnaires. Upon analysis, it was found that women who had lost ten or more pounds during a dieting bout, and/or who dieted frequently, had depressed immune systems relative to those whose weight had remained stable over time. However, the researchers make it clear that they are not suggesting that those who are overweight or obese should not lose the excess weight. What the study does indicate is that weight loss should be relatively slow, steady, and permanent if the immune system is to maintain optimal functionality. Shade ED, Ulrich CM, Wener MH, Wood B, Yasui Y, Lacroix K, Potter JD, McTiernan A. Frequent intentional weight loss is associated with lower natural killer cell cytotoxicity in postmenopausal women: possible long-term immune effects. J Am Diet Assoc. 2004 Jun;104(6):903-12.
AnthroHealth Tip of the Month: In accord with this month’s Greeting, this month’s Tip is to pause and reflect on optimizing your health by re-reading and practicing the Tips from prior issues of AnthroHealth News.
© 2001-2009 Kathleen E. Fuller, PhD. All rights reserved.