Dietary restriction and aging in rhesus monkeys<br />By: J.J. Ramseya, R.J. Colmana, N.C. Binkleya,b, J.D. Christensena,T.A. Gresla, J.W. Kemnitza,c, R. Weindrucha<br />Caloric Restriction Extends Life in Monkeys<br />“Eat Less You Will Live Longer”<br />Name: QossayTakroori<br />Professor: Dr.JefferyRothweiler<br />Class: Human Growth and Development<br />
Questions being addressed:<br /><ul><li>The study is about that relationship between diet and life span. In 1989, a longitudinal study was started to determine whether restricted diet is linked to the incensement of life expectancy in monkeys.
Theories: According to previous research, dietary restriction (DR) slows the aging process in laboratory mice and rats based on its ability to oppose the development of a broad spectrum of age-associated diseases and extend maximum lifespan. Moreover, the maximum life span of non-mammals is also increased by dietary restrictions.
Questions being asked: Life expectancy (the average life span) greatly increased during the 20th century in most countries, largely due to improved hygiene, nutrition, and health care. One possible approach to further increase human life span is “caloric restriction.” But does restricted diet have similar action in a primate species? Like Monkeys? Would RD enhance monkeys lives?
Purpose: Advance the development of the rhesus monkey as a model for the study of aging. Second, determine the influence of DR on the rate of aging in this primate species. Could the model “restricted diet” be applied on human in order to increase our life span, and improve the quality of our lives?</li></li></ul><li>The Methods Used:<br /><ul><li>Operationalized: The study took around 25 years, which means it’s a longitudinal study. The initial study began in 1989 to investigate the effects of a 30% DR in 30 adult male rhesus monkeys. In 1994, an additional 30 females and 16 males were added to the study. The independent variable is diet or dietary restriction and the dependent variable is life span.
Preparation and operation: </li></ul>Environment:<br />They had extensive visual and auditory contact with other monkeys. The animals were allowed continuous access to water, and the animal rooms were maintained at 21±26C with, 50±65% relative humidity. Artificial room light is automatically controlled to provide 12-h light and dark period. <br /> <br />2. Health Care Routine:<br /> <br />The monkeys were test daily for health problems, injuries or any other complications. Among the 12 controls in Group 1, three animals became pre-diabetic versus none in the DR group.<br /> <br />3. Diet:<br />All animals are fed a semi-purified diet which contains 15% lactalbumin, 10% corn oil and approximately 65% carbohydrate in the form of sucrose and corn starch The composition of the restricted and control diets is similar, but the restricted diet is supplemented with an additional 30% of the vitamin and mineral content to ensure that the groups, on average, consume a similar amount of micronutrients. Food intake is measured for each animal daily. All animals are fed in the morning and, at approximately 4 PM, any food remaining in each cage is removed and weighed. Intakes for individual animals are averaged weekly and summarized over a six-month period. The research team reduced the RD group by 30 percent over the past three months, but 30% percent diet reduction was too much for two of the animals because their body fat decreased to 3% followed by pale face, illness, and hair lost. The team decided in 1996 to increase the daily food intake to these animals in order to increase their body fat to 5% to maintain healthy body. <br /> <br />
The Methods Used:<br /><ul><li> Measurements and calculations:</li></ul> <br />Most measurements are completed annually within a single, six-week assessment period. During Week 1, blood samples are collected for CBC (Complete Blood Count), chemistry panels, endocrine measurements and measurement of skeletal parameters. DXA measurements of body composition are also completed during Week 1. Urine collections are completed during Week 4 and indirect respiration calorimetrymeasurements of energy expenditure are completed in Week 5. Finally, during Week 6 of the assessment period, a frequently sampled intravenous glucose tolerance test<br />(FSIGT) is done.<br />
Summery and Results<br /><ul><li> A 20-year study found that Rhesus monkeys fed a nutritious, low-calorie diet have fewer age-related diseases than counterparts on a normal diet, also, results show that calorie restriction helps preserve primates’ bodies and brains, says Luigi Fontana, of Washington University in St. Louis.. Calorie restriction has already been shown to extend the lifespan of mice and dogs, as well as yeast, fruit flies and worms. Life span of Rhesus monkeys is 40 years, but with the RD experiment, some of the monkeys like Owen 19 years old slowed his aging process significantly.
Since the study began, 21 of 38 control monkeys and 14 of 38 calorie-restricted monkeys have died. Of the control monkeys, 14 died of age-related causes, such as cancer, heart disease or diabetes. In the calorie-restricted group, only five died from aging-associated diseases, and none have developed symptoms of diabetes.
As excepted the RD groups showed significant difference in body weight compared to the control group. They also were at much lower risk of developing bone disease, because osteoblast was stimulated to produce more bone making bone much denser and stronger.
It has also been proposed that aging is the result of accumulated damage caused by oxygen free radicals</li></ul>produced during aerobic metabolism. The DR group was more active and had higher energy than the control group, this would help minimize the free radicals that slows that aging process. RD helped the monkeys to walk, behave, and think much effectively than control group after they closely monitored after and before the meals. Bad cholesterol was reduced during the experiencement which results in healthier heart, and less chances of heart diseases. <br /> <br /> <br />.<br />
Critique: <br /><ul><li>I think the study is great to give us a better understanding of human development and aging. Once we establish this understanding, we will be able to better educate people about the benefits of RD in order to enhance the quality of our lives, and to reduce the risk of deadly diseases such as heart disease, diabetes and cancer. The study finding could be replicated on other animals to see whether RD would expend live span as it did in Spiders, fish and non-mammals. However, the methods might be different because of the different nature of the animals.
In terms of internal validity, the groups were selected randomly, meaning there was no bias. But two of the threats were “Instrument change and mortality”. Some of the monkeys died other has sever health complications.
According to the study, RD monkeys had better health, energy and motivation. So, we as a community can take the results from this study and apply parts of it on our daily life to see whether our life will improve, or not.
It will be very hard, I don’t think that we can resist not eating enough food especially rich food, and also it will be difficult to monitor people for years and years. Scientists were able to control the monkeys because they put them in cages, and restricted what they eat and do. </li>