The World Health Organization observed in 2015 that the average lifespan of the global population is 71.4 years. That number of years can be reduced by several factors, such as diet, exercise, sleeping patterns, and lifestyle habits. According to a recent trial, manipulating the metabolism can slow down the aging process and can prevent age-related diseases.

Slower Metabolism for Longer Life

Metabolism is composed of chemical processes that occur in a living organism to maintain life. There three main purposes of metabolism in living organisms which are conversion of food to energy, conversion of food to essential compounds, and removal of wastes made of nitrogen compounds.

1. Conversion of food to energy: Living organisms hunt or gather food or fuel in order to live. The food or fuel is converted by the organism to generate energy. The energy is used by cells to perform processes, such as repair and reproduction. Most animals eat food to gain energy while plants gather sunlight through photosynthesis to get energy.

2. Conversion of food to essential compounds: The food or fuel obtained by living organisms can also be broken down by enzymes to produce essential compounds, such as proteins and lipids. These essential compounds are used to nourish cells, tissues, and organs.

3. Removal of nitrogenous wastes: The food or fuel obtained by living organisms contain nitrogen, and any excess is eliminated from the body. Living organisms excrete the excess nitrogen as waste such as creatinine or urea. In most animals, the excretion of wastes is done with urination or defecation.

In relation to the aging process, previous research found that a slower metabolic rate can slow down aging. A faster metabolism leads to rapid burning of energy or calories, the unit of measurement of energy provided by food or fuel, which results in quick weight loss. Conversely, a slower metabolism leads to gradual burning of energy and sluggish weight loss. The idea of having a fast metabolism seems to be a great thing for those struggling with weight loss, but the trait has a huge downside – shorter life expectancy.

The Comprehensive Assessment of the Long-Term Effects of Reducing Intake of Energy or CALERIE is the first randomized controlled trial which examines the effects of calorie restriction in metabolism among non-obese people. In the second phase of the trial, the researchers enrolled 53 healthy, non-obese men and women, aged 21 to 50, who were instructed to cut their calorie intake by 15 percent for two years. The researchers measured their metabolism and oxidative stress for over two years to get accurate readings.

Results found that the participants who cut their calorie intake lost nearly nine kilograms on average, even though they did not follow any specific diet and the study's focus was not about weight loss. The researchers noted that no participant has suffered from adverse reactions, such as anemia, excessive bone loss or issues with the menstrual cycle. In fact, the trial led to positive effects, such as improved health-related quality of life and better moods. The slow aging effect of calorie restriction could be derived from factors that influence metabolism, such as diet and antioxidants.

"The CALERIE trial rejuvenates support for two of the longest-standing theories of human aging: the slow metabolism 'rate of living' theory and the oxidative damage theory," said Leanne Redman, the lead author of the study and an associate professor of Clinical Sciences at Pennington Biomedical Research.

Even though the study has been small in scale, the participants were still able to gain benefits from the calorie restriction. So, the researchers decided to push the study that will involve the establishment of robust biomarkers of human aging and the connection of calorie restriction with antioxidant-producing foods.

Antioxidants and Oxidative Stress in Metabolism

Oxidative stress is an imbalance between the production of free radicals and the counteract mechanism of the body to eliminate them. Free radicals are molecules of oxygen that contain one or more unpaired electrons. These unpaired electrons are highly reactive with other molecules in cells that may cause cellular damage. Most common free radicals include hydrogen peroxide, organic hydroperoxide, superoxide anion, and hypochlorous acid.

Oxidative stress can lead to several diseases such as:

- Neurological disorders including Alzheimer's disease and Parkinson's disease.

- Cardiovascular diseases including atherosclerosis and heart failure.

- Metabolic diseases including diabetes and hypothyroidism.

- Abnormal growth and mutations that often lead to cancer.

Antioxidants are molecules found in cells that prevent the effects of oxidative stress. Cells donate these molecules to free radicals to stabilize them and become low reactive to other cells. Diet, exercise, sleeping patterns, and lifestyle habits can affect the balance between antioxidants and free radicals. For instance, an individual who only eats meat and smokes heavily is more prone to free radicals from the toxic chemicals of cigarettes and the lack of essential nutrients. The abundance of free radicals in the body can overrun cells with antioxidants that can result in disorders and diseases. Eating a healthy diet and living an active and positive lifestyle can help increase antioxidants and reduce free radicals.

[메디컬리포트=Ralph Chen 기자]

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