Positive and negative properties of caffeine

Author: Mikhail Ziborov - author of the site makefitness.pro.
2020-03-25

Have you seen the memes with the phrase "The morning doesn’t start with coffee"? Well, for many, it actually does start with it, and for some even with WORKOUT. This article will discuss the benefits and drawbacks of caffeine. So sit back and get comfortable.

What is caffeine and how does it affect humans?

Caffeine is an alkaloid, a substance with a range of both positive and negative effects. You can obtain it directly from coffee, all types of tea, cocoa, from supplements like caffeine tablets, guarana, or ginseng, or in the form of certain types of sports nutrition like pre-workout complexes and fat burners (stimulants).

Caffeine content in various coffee varieties ranges from 0.6% to 2.7% of the total composition. After drinking a cup of coffee or taking tablet/capsule caffeine, it is absorbed in the intestines and enters the bloodstream. From there, it travels to the liver, where it begins to exert various effects on our body. Its maximum effectiveness occurs 40-60 minutes after consumption, although the first signs of its action start after about 20 minutes.

To date, over 19,000 studies have been conducted on coffee and caffeine: it is the second most researched sports supplement after creatine.

Positive aspects of caffeine

For everyone

1. Reduces fatigue. Caffeine blocks adenosine, sharing a similar structure: it attaches to adenosine receptors, preventing the adenosine itself from binding. As a result, fatigue is reduced (it sets in later). By drinking 4-5 cups of espresso, you can block about 50% of adenosine receptors, which is quite a significant result. Therefore, caffeine doesn’t wake you up; it simply blocks the neurotransmitter responsible for fatigue.

2. Increases concentration and alertness. This can be useful in sports (to better feel the working muscle group, for example) or during mental tasks. This is achieved by stimulating greater production of hormones like adrenaline. Adrenaline, in turn, increases the production of dopamine and norepinephrine—the pleasure hormone and the hormone responsible for transmitting nerve impulses, respectively. These hormones excite the nervous system while imposing their other effects. Reference: “Caffeine in foods: A Comprehensive Review on Consumption, Functionality, Safety, and Regulatory Matters, 2010.”

3. Reduces mortality from all causes (cancer, stroke, and other internal organ diseases) compared to those who do not drink coffee at all. This information can be found in the article “Coffee: Harm, Benefit and... Enjoyment” by Boris Tsatsulin on cmtscience.ru, where two large studies conducted in Europe and the USA are mentioned. The mortality rate for coffee drinkers was 12% lower compared to those who do not consume coffee or caffeine (the difference grew to 18% for those drinking more than 3-4 cups).

4. Scientists from different countries have found that coffee improves cognitive functions of the brain (reducing the risk of developing corresponding diseases, such as Alzheimer's or Parkinson's). This is confirmed by the first three studies mentioned in the Telegram channel of Andrey Skoromny in the article "Caffeine (Expanded Review)."

5. Reduces depression. People who consume caffeine suffer 13% less from depression than those who do not. Reference: “Coffee, tea, caffeine and risk of depression: A systematic review and dose-response meta-analysis of observational studies, 2015.”

For athletes

1. Suppresses (not too strongly, but still) appetite and increases calorie expenditure by the body (due to a slight metabolic boost). However, experiments were conducted on mice: the study “Caffeine inhibits hypothalamic A1R to excite oxytocin neuron and ameliorate dietary obesity in mice” is presented in the journal Nature Communications.

2. Increases the rate of fat burning (by 13%) through the thermal effect and energy expenditure (by 79 kcal per day).

3. Increases the volume of glycogen that muscles can use (availability) and delays the onset of exhaustion.

4. Improves endurance (by 5%) when using a dosage of 5 mg of caffeine per kg of body weight and taken an hour before training.

5. Enhances physical qualities such as strength, endurance, and speed during weight training. This is particularly relevant in sports like CrossFit or when performing complex exercises with short rest periods between sets.

To learn more and verify the research on the last four points, you can check the same Telegram channel of Andrey Skoromny in the article on the expanded review of caffeine.

Negative aspects of caffeine

Caffeine can raise blood cholesterol levels. Studies have shown that it increases plasma cholesterol concentration by 8-10% in both women and men when consumed regularly. However, instant coffee contains significantly less of the substance that leads to such results, meaning it doesn’t elevate cholesterol levels as much (article “Coffee: Harm, Benefit, and… Enjoyment” on cmtscience.ru).

It affects calcium excretion from the body, so it is not recommended for elderly individuals with osteoporosis (who already have lower calcium levels) and for growing children, as their bones may become soft due to a higher proportion of connective proteins than solid calcium structures.

It impacts the fetus in pregnant women. American and Danish scientists found that children born to women who drank 1-2 cups of coffee a day during pregnancy had a lower birth weight (about 20% less than normal). However, this is more a concern related to coffee as a whole rather than caffeine specifically. Heart defects and cleft lips in children are consequences of pregnant mothers consuming more than 200 mg of caffeine per day.

Fatigue can hit even harder than before. Remember how caffeine occupies adenosine's place on receptors? While caffeine binds to these receptors, adenosine doesn’t go away; it accumulates. Once the caffeine clears, all that accumulated adenosine floods back to those receptors. In simpler terms, coffee/caffeine postpones fatigue, but it will come back with greater intensity.

It can lead to dependence: you might find it hard to wake up without coffee and perform adequately. Therefore, caffeine isn’t a drug (there are no withdrawal symptoms, just a lack of energy), but it’s easy to get used to. Why would your body exert extra effort when you're providing it with energy for free? The same applies to workouts: if you get used to consuming it before exercising, whether in pure form or in pre-workout complexes, you will eventually need larger doses.

The number of adenosine receptors increases. With daily caffeine intake of around 300 mg, the number of these receptors rises. Now, imagine you skip coffee or drink significantly less than usual. There are now more spots (receptors) available for adenosine (the neurotransmitter of fatigue). What do you think the outcome will be? An overwhelming fatigue that you didn’t recognize before. After stopping caffeine or coffee, the volume of receptors decreases, and everything quickly normalizes.

Myths about caffeine/coffee

Caffeine does not negatively affect the heart. While caffeine increases heart rate, it does not affect heart health (physical activity also increases heart rate—so what?). The result has even been the opposite: a meta-analysis by a Chinese scientist involving 228,000 people showed that coffee drinkers had a 6% lower incidence of atrial fibrillation.

It does not dilate blood vessels. Many textbooks state that caffeine dilates blood vessels. However, recent findings (thank you, Harvard School of Public Health) indicate that blood vessels only slightly dilate, and this dilation has no significant impact. If we talk about blood pressure, it increases due to a rise in the frequency and strength of heart muscle contractions. Dilation is more associated with theobromine than caffeine.

Interesting point

I came across a post by Fyodor Serkov on Instagram about caffeine from November 23, 2019. You can find out more about him yourself. The guy noted that caffeine tablets can lose their stimulating effect over time despite their expiration dates. Keep that in mind.

Sources

For more detailed information about caffeine and coffee, you can read the articles “For the Hundredth Time About Coffee” and “About Caffeine” on cmtscience.ru.

Telegram channel “Skoromny.”

For research, simply copy the titles and paste them into a search engine.

Conclusion

In summary, caffeine has its positive and negative aspects. The takeaway is simple: consume it in moderation and take breaks if you're using tablet caffeine or supplements/sports nutrition, or don’t overdo it with caffeinated beverages. This way, you’ll experience only the benefits of this compound while minimizing side effects.