Tag Archives: science

How do we adapt to high altitude?

When I first moved to Canada, my family decided to settle in Calgary. After a couple of weeks, I constantly felt tired and out of breath. I went to a doctor and she said this was symptoms of hypoxia, a high-altitude sickness; the recovery time should be fast since Calgary don’t have an extreme altitude. After a few weeks, the symptoms of hypoxia were gone, but it took a lot longer until I could feel comfortable to join any strenuous exercise.

City of Calgary

A question arose from my experience, why it took me that long to adapt to the high altitude while the symptoms of hypoxia were gone within a few weeks.

The simplest answer is considering this scenario the same as if you catch the flu. The sense of illness could be gone within days; however, full recovery might take up to weeks.

A detailed explanation of high-altitude adaptation involves separating it into third processes and also taken into the consideration of how much above sea level are we talking about.

When we divide the adaptation process into three sections (figure 1), the first part happens right after entering a high-altitude environment. During this period, an individual will experience symptoms of hypoxia and there will be a significant decrease in fitness level. This is a result of low blood oxygen level, which is caused by decreasing air pressure at higher altitude. Since there is less oxygen in the blood, breath rate and heart rate will increase dramatically even during the resting time in order to maintain body basic functions, this will cause overstress on cardiac muscles.

figure 1: The initial response to high altitude exposure. Image retrieve from https://www2.palomar.edu/anthro/adapt/adapt_3.htm

In the second part (figure 2), an acclimatization process would happen, which means the body will make adjustments to stop the decrease in fitness level. To lower the increased cardiac output, our body would produce more red blood cell in capillaries to carry more oxygen, so that the cardiac muscles were less stressed. Failing of acclimatization with low blood oxygen level would cause tissue hypoxia, decreased cardiac output and decreased red-blood-cell concentration. In this case, this individual couldn’t adapt at this altitude and the doctor would suggest moving back to a lower altitude.

figure 2: Acclimatization process. Image retrieve from https://www2.palomar.edu/anthro/adapt/adapt_3.htm

For the third section (figure 3), the result will vary depending on the altitude. With an altitude below 10000ft, physiological adjustment takes time and eventual fitness level will return back to normal. With even higher altitude (above 12000ft), successful acclimatization rarely happens; even if an individual is able to live on the plateau, strenuous exercise and memorization task still remain difficult.

figure 3: Successful acclimatization. image retrieve from https://www2.palomar.edu/anthro/adapt/adapt_3.htm

The failure to adapt to extremely high altitude is not caused by physiological limitation. A study shown for those populations that living on extreme high altitude, shared sections of unique genetic sequence that reduce hypoxia. One of these genes is EPAS1, which is activated by low blood oxygen level and is responsible for lowing hemoglobin concentration in blood for sufficient delivery of oxygen around the body.

The Tibetan Plateau

In addition, physiological adaptation at high altitude increase cardiovascular strength and this characteristic is used to advantage by some endurance athletes.  (figure 4) Altitude training is a several weeks training at intermediate altitude (preferably over 8,000 ft). At intermediate altitude, there is still approximately 20% oxygen, but the partial pressure of oxygen is reduced. The reduction in oxygen partial pressure forces athletes’ body to acclimate to the lack of oxygen, thus producing more hemoglobin and altering muscle metabolism. The increase in hemoglobin concentration and muscle metabolism will give athletes a competitive advantage that lasts up to 10 ~14 days.

figure 4: Increase in fitness after acclimatization. Image retrieve from https://www2.palomar.edu/anthro/adapt/adapt_3.htm

In conclusion, our body is able to make some physiological adaption to the environment until it reaches some limitation. When traveling to higher altitude area, it is important to check your health condition in order to avoid unnecessary damage to your body. Also, a short-term introduction of intermediate altitude is a common training method for the athlete to increase their body condition and gain competitive advantages.

Information attribute from:
Altitude training. (2018, October 14). Retrieved October 21, 2018, from https://en.wikipedia.org/wiki/Altitude_training
Duffin, J. (2014). Faculty of 1000 evaluation for Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA. F1000 – Post-publication Peer Review of the Biomedical Literature. doi:10.3410/f.718477234.793496726
O’Neil, D. (n.d.). Human Biological Adaptability: Adapting to High Altitude. Retrieved from
https://www2.palomar.edu/anthro/adapt/adapt_3.htm

 

5 ways to eat eggs bad for your health

Why people need to eat eggs

Eggs are one of the healthiest and the most commonly consumed food in the world. 

They have a high nutritional value because they contain various trace elements and kinds of essential vitamins needed by the human body, such as protein, vitamin D, B vitamins, minerals, and so on. 

 

Recent news about eating eggs

With the improvement of living conditions, people’s requirements on diet have been gradually improved. In today’s society, people are more and more about their health. As part of a balanced diet, people like to eat eggs to supplement nutrition. However, recent news on newspapers shows eats eggs can cause heart disease because of the high protein. Therefore, whether eating eggs bad or good to human health has caused concern.

High protein in eggs

The protein required for people is 0.8g per kilogram of body weight.

According to the dietary reference intake for protein, we can find:

  1. 56g protein required by the average sedentary man per day
  2. 46g protein required by the average sedentary woman per day

One large egg can provide about 6g protein, which makes up over 10% of the average sedentary man required per day and 12.5% of the average sedentary woman required per day.

To prevent side effects of eating eggs, people should pay attention to the following ways of eating eggs.

1. Eating raw eggs

Some people think that if food is cooked, it would lose its nutritional value. Therefore, many people like to eat raw vegetables and seafood, and they think that raw eggs have a higher nutritional value than cooked eggs.

However, eating raw eggs are more likely to carry bacteria, such as coli into the stomach, which can cause gastrointestinal discomfort and Diarrhea. In addition, the raw egg white contains Avidin, which only can be destroyed by high temperature. The Avidin can affect the absorption of the biotin in food, and cause many unpleasant symptoms, such as inappetence, muscle ache, skin inflammation, eyebrow fell off, and so on.

2. Cooking eggs for a long time

Some people think that more time used to cook eggs, it is better for human health. However, it is also wrong because if the egg is cooked for a long time, the ferrous ions in the yolk would combine with the sulfur ions in the egg white to form the insoluble ferrous sulfide, which is difficult to be absorbed. 

Also, fried eggs would be too old and the edges would be scorched when they are cooked for a long time. The polymer-protein in the egg white can form low molecular amino acid, which could form harmful chemicals to human health under high temperature.

3. Eating too many eggs in a day

If people eat too many eggs, the metabolites and the burden on the kidneys would increase, which can cause kidney failure symptoms. 

Here are a few effective tips:

For the elderly people, they can eat 1~2 eggs per day.

For the young and middle-aged people who engage in mental work or light manual labor, they can eat 2 eggs per day.

For people who engage in heavy manual labor, they need to consume more nutrition. So they can eat 2~3 eggs per day.

For young children, they can eat 2~3 eggs per day because of their fast metabolism.

For Pregnant women, lying-in women, breastfeeding women, individuals with weak immune systems and the patient that undertakes postoperative convalescence, they can eat 3 ~ 4 eggs per day because they need to get enough protein.

4. Eating eggs with sugar or soy milk

Many people like to cook eggs with sugar, but eggs can react with sugar under high temperature, and produce a substance called Glycolysis, which can destroy the amino acids in eggs. It is important to note that glycolysis has side effects on blood coagulation, which can harm human health. Therefore, people should leave eggs cool down before adding sugar.

In addition, many people like to have an egg, a bread, and a cup of soy milk for breakfast. In fact, the Trypsin in soy can combine with the egg pine protein in the egg white, which can cause nutrient loss and reduce their nutritional value.

5. Eating excess eggs on an empty stomach

If people consume excessive food with high protein, such as milk, soy milk, eggs and meat, the protein would be conversed forcedly into energy consumption, which cannot provide nutrition to people.

What’s more, when human body accumulates excess protein in a short period, the protein decomposition process can produce a variety of harmful substances that can bad for human health, such as urea, ammonia compounds, and so on.

In brief, if people pay attention to ways to eat eggs, eating eggs can help people meet their demand for protein, and it can bring many advantages to human health.

Information Attribute from:

Denise Hill: https://www.lifehack.org/488728/10-foods-to-eat-and-avoid-on-an-empty-stomach-for-better-digestive-health

Estherjane13: http://www.thewholesomefork.com/2017/02/23/how-many-eggs-is-it-safe-to-eat-per-day/

Haley Hernandez: https://www.click2houston.com/health/is-eating-eggs-good-or-bad-for-you-

Healthline: https://www.healthline.com/nutrition/eating-raw-eggs#section3

Healthline: https://www.healthline.com/nutrition/eating-healthy-eggs

GirlsTalkinSmack: http://women.girlstalkinsmack.com/Food/foods-you-should-not-eat-with-eggs.aspx

Jayne Leonard: https://www.medicalnewstoday.com/articles/323251.php

 

 

Zhou LU

What are Telomeres?

Telomeres are like the plastic tips at the end of the shoelaces; they are the caps at the end of each strand of DNA and they protect our DNA from becoming damaged.

Telomeres were first distinguished in 1933 by Dr. Barbara McClintock. Recent research lead Dr. Carol Greider, and Dr. Jack Szostak to be awarded the 2009 Nobel Prize in Physiology or Medicine for the discovery of how chromosomes are protected by the enzyme telomerase and telomeres.

Diagram of Chromosome Showing Telomeres in Green Credit: Beauty Black Book

Telomeres Shorten as We Age

Each cell in our bodies replicates DNA and divides. DNA polymerase is the enzyme in charge of DNA replication, but it is incapable of replicating the entire chromosome strand.  Telomeres serve as a “scape goat” of dispensable DNA not needed for vital functions, so when DNA polymerase is ready to fall off the chromosome some of this dispensable DNA is lost.

How Much Telomeres Do We Lose in a Lifetime?

To put it in perspective, we are born with about 11 kb of telomeres, that’s 11,000 base pairs of DNA. By old age, we have approximately 4 kb or 4,000 base pairs.

This significant decrease in telomeres suggests that each cell has a maximum number of cell divisions before it must induce its own cell death. Dr. Leonard Hayflick extensively studied this phenomenon and concluded that each cell can only divide up to 60 times. The maximum number of cell divisions is now known as The Hayflick Limit.

Diagram Showing Decrease of Telomere Length with Age Credit: Defytime

Promising Study on Progeria Cells

Scientist are in hot pursuit to find the fountain of youth. Dr. John Cook and his team conducted an experiment with promising results and with the intentions of helping children with progeria, a rare genetic condition which speeds up aging.

In the study, the participants, aged 1 to 14 years-old, had telomeres lengths of a 69-year-old. Telomeres length was significantly increased in progeria cells as measured by expression of telomerase.

Video on Study on Progeria Cells by Dr. John Cook Credit:  Vimeo

Although this study is very promising, other scientists believe delaying the natural decline of telomere length could be harmful. Dr. Peter Lansdorp from the University of British Columbia explains that telomere shortening is a defense mechanism built within our cells to decrease the chances of developing cancers. Shortening telomere length of cancerous cells causes them to die. Halting this mechanism would allow cancer cells to continue to divide to create tumors.

What Speeds Up and Slows Down Aging?

Studies have shown that following a healthy diet, regular exercise, managing stress, and increase sleep is associated with longer telomeres, whereas higher body mass index, high stress, and smoking are associated with shorter telomeres.

Table of Factors that Affect Telomere Length Credit:  Indian Journal of Medical Research

https://soundcloud.com/sciencetoday/telomere

Podcast on Telomeres as Marker of Aging Credit: US Science Today SOUNDCLOUD

Stress Less Live longer!

Studies suggest that any type of stress will have an effect on your telomeres and will in turn speed-up the aging process. It also shows that taking good care of yourself will  delay the aging process. So next time you feel stressed out, take a second to breath. Your biological clock will thank you.

Video of The Science of Aging Credit: ASAP Science YouTube

Maria-Fernanda Arcila