We ingest antioxidants as if they were a magic elixir that could prolong our life. However, at best, they are simply ineffective, and at worst, they can shorten our earthly path. BBC Future columnist explains why.
Linus Pauling made a serious mistake when he decided to change a few things in his traditional breakfast.
In 1964, at the age of 65, he began adding vitamin C to orange juice, which he drank in the morning.
It was like adding sugar to Coca-Cola, but he sincerely and even too zealously believed that it was useful.
Before that, his breakfasts were hardly unusual. The only thing that deserves special mention is that he had breakfast early in the morning before heading to work at Caltech, even on weekends.
He was tireless, and his work was exceptionally fruitful.
At the age of 30, for example, he proposed a third fundamental law of the interaction of atoms in molecules, based on the principles of chemistry and quantum mechanics.
Twenty years later, his work on the structure of proteins (the building blocks of all life) helped Francis Crick and James Watson decipher the structure of DNA (which encodes this material) in 1953.
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The following year, Pauling was awarded the Nobel Prize in Chemistry for his research on the nature of chemical bonds.
Nick Lane, a biochemist at University College London, wrote about him in his 2001 book Oxygen: "Pauling … was a colossus of 20th century science whose work laid the foundations of modern chemistry."
But then the "age of vitamin C" began. In his 1970 bestseller, How to Live Longer and Feel Better, Pauling stated that supplementation with this vitamin can help fight colds.
He was taking 18,000 mg (18 g) of this substance per day, which, by the way, is 50 times higher than the recommended daily value.
In the second edition of this book, flu was added to the list of diseases that vitamin C effectively fights against.
In the 1980s, when HIV began to spread in the United States, Pauling stated that vitamin C could cure the virus as well.
In 1992, Time magazine wrote about his ideas, on the cover of which the headline "The Real Power of Vitamins" flaunted. They have been touted as a cure for cardiovascular disease, cataracts, and even cancer.
“Even more tempting is the suggestion that vitamins can slow the aging process,” the article said.
Sales of multivitamins and other nutritional supplements skyrocketed, as did Pauling's fame.
However, his scientific reputation, on the contrary, suffered. Scientific studies over the next few years have shown little or no evidence for the benefits of vitamin C and many other supplements.
In fact, every spoonful of vitamin Pauling added to his orange juice was harming rather than helping his body.
Science not only refuted his judgments, but also found them quite dangerous.
Pauling's theories were based on the fact that vitamin C belongs to antioxidants - a special category of natural compounds, which also includes vitamin E, beta-carotene and folic acid.
They neutralize highly reactive molecules known as free radicals and are therefore considered beneficial.
In 1954, Rebecca Gershman, then at the University of Rochester, New York, first identified the dangers associated with these molecules.
In 1956, her hypothesis was developed by Denham Harman of the Laboratory of Medical Physics at the University of California at Berkeley, who stated that free radicals are the cause of cell destruction, various diseases and, ultimately, aging.
Throughout the 20th century, scientists continued to research this topic, and soon Harman's ideas gained universal acceptance.
This is how it works. The process begins with mitochondria, microscopic engines inside our cells.
Inside their membranes, nutrients and oxygen are converted into water, carbon dioxide and energy.
This is how cellular respiration occurs - a mechanism that serves as a source of energy for all complex forms of life.
Leaking water mills
But it’s not that simple. In addition to nutrients and oxygen, this process requires a constant flow of negatively charged particles - electrons.
The flow of electrons passes through four proteins found in mitochondrial membranes, which can be compared to watermills. So he participates in the production of the final product - energy.
This reaction is at the heart of all our activities, but it is not perfect.
Electrons can "leak" out of three cell mills and react with nearby oxygen molecules.
As a result, free radicals are formed - very active molecules with a free electron.
To restore stability, free radicals wreak havoc on the systems around them, taking electrons from vital molecules like DNA and proteins to maintain their own charge.
Harman and many others have argued that, although small in scale, free radical formation gradually damages the entire body, causing mutations that lead to aging and related diseases such as cancer.
In short, oxygen is the source of life, but it can also be a factor in aging, disease, and finally death.
Once free radicals were linked to aging and disease, they were viewed as enemies to be expelled from our bodies.
In 1972, for example, Harman wrote: “Reducing the amount [of free radicals] in the body is expected to reduce the rate of biodegradation, thereby giving a person additional years of healthy life. We hope that [this theory] will lead to fruitful experiments aimed at increasing the duration of a healthy human life."
He talked about antioxidants - molecules that take electrons from free radicals and reduce the threat they pose.
And the experiments he hoped for were carefully conducted and repeated many times over several decades. However, their results were not very convincing.
For example, in the 1970s and 80s, various antioxidant supplements were given to mice - the most common laboratory animal - with food or by injection.
Some of them have even been genetically modified so that genes for certain antioxidants are more active than in normal laboratory mice.
Scientists have used different methods, but they got very similar results: the excess of antioxidants did not slow down aging and did not prevent disease.
“No one has been able to reliably prove that they (antioxidants - Ed.) Can prolong life or improve health,” says Antonio Henriquez of the National Center for Research on Cardiovascular Diseases in Madrid, Spain. "The mice didn't react much to the supplements."
What about people? Unlike our smaller brothers, scientists cannot place members of our society in laboratories in order to track their health throughout their lives, and also exclude all external factors that may affect the final result.
The only thing they can do is organize a long-term clinical trial.
Its principle is very simple. First, you need to find a group of people of about the same age, living in the same area and leading a similar lifestyle. Then you need to divide them into two subgroups.
The first receives the supplement to be tested, while the second receives a pill or placebo.
To ensure the purity of the experiment, no one needs to know what exactly the participants are getting before the end of the study - even those who dispense the pills.
This technique, known as double-blind testing, is considered the benchmark in pharmaceutical research.
Since the 1970s, scientists have conducted many similar experiments trying to figure out how antioxidant supplements affect our health and longevity. The results were disappointing.
For example, in 1994, a study was organized in Finland with the participation of 29,133 smokers aged 50 to 60 years.
In the beta-carotene supplement group, the incidence of lung cancer increased by 16%.
Similar results were obtained by an American study involving women who entered the postmenopausal period.
They took folic acid (a type of B vitamin) every day for 10 years, and thereafter, their risk of breast cancer increased by 20% compared to those who did not take the supplement.
It only got worse from there. A study of more than 1,000 heavy smokers published in 1996 had to be discontinued about two years ahead of schedule.
After just four years of taking beta-carotene and vitamin A supplements, lung cancer cases increased 28% and deaths 17%.
And these are not just numbers. The supplement group had 20 more deaths each year than the placebo group.
This means that 80 more people died in the four years of the study.
Its authors noted: "The study results provide a strong case for not taking beta-carotene supplements, as well as beta-carotene in combination with vitamin A."
Fatal ideas
Of course, these noteworthy studies do not give us the full picture. Some trials have shown the benefits of antioxidants, especially in cases where participants were unable to eat properly.
However, the findings of a 2012 scientific review based on 27 clinical trials of the effectiveness of various antioxidants do not favor the latter.
In only seven studies, supplementation was found to have some degree of health benefit, lowering the risk of cardiovascular disease and pancreatic cancer.
Ten studies did not show any benefits of antioxidants - the results were as if all patients were receiving a placebo (although in reality this, of course, was not the case).
The results of the remaining 10 studies indicated that many patients were in significantly worse condition than before taking antioxidants. In addition, among them, the incidence of lung cancer and breast cancer increased.
“The suggestion that antioxidant supplementation is a magic cure is completely unfounded,” says Henriquez.
Linus Pauling did not even know that his own ideas could be deadly.
In 1994, before the publication of the results of numerous large-scale clinical trials, he died of prostate cancer.
Vitamin C was not a panacea at all, although Pauling insisted on it until his last breath. But is its increased consumption associated with additional risks?
It is unlikely that we will ever know for sure. However, given that many trials link antioxidant intake to cancer, this is not entirely out of the question.
For example, a 2007 US National Cancer Institute study found that men who took a multivitamin had twice the risk of dying from prostate cancer than those who did not.
And in 2011, a similar study in 35,533 healthy men found that taking supplements with vitamin E and selenium increased the risk of prostate cancer by 17%.
Since Harman proposed his famous theory of free radicals and aging, scientists have gradually abandoned the clear separation of antioxidants and free radicals (oxidants). It is now considered obsolete.
Antioxidant is just a name that does not fully reflect the nature of a particular substance.
Take, for example, Pauling's beloved vitamin C. When dosed correctly, it neutralizes highly active free radicals by taking away a free electron. He becomes a "molecular martyr", taking the blow and protecting the cells around him.
However, by accepting an electron, it itself becomes a free radical, capable of damaging cell membranes, proteins and DNA.
As food chemist William Porter wrote in 1993, "[Vitamin C] is the true two-faced Janus, Dr. Jekyll and Mr. Hyde, an oxymoron of antioxidants."
Fortunately, under normal circumstances, the reductase enzyme is able to restore vitamin C to its antioxidant appearance.
But what if there is so much vitamin C that the enzyme simply cannot handle it?
Despite the fact that such a simplification of complex biochemical processes is not able to reflect the essence of the problem, the results of the above clinical studies indicate what this can lead to.
Divide and rule
Antioxidants have a dark side. In addition, even their bright side does not always work for our good - in the light of the growing evidence that free radicals are also important for our health.
We now know that free radicals often act as molecular messengers that send signals from one part of the cell to another. So they regulate the processes of growth, division and cell death.
Free radicals play a very important role at every stage of a cell's existence. Without them, cells would continue to grow and divide uncontrollably - a process called cancer.
Without free radicals, we would also be more likely to get infections. Under conditions of stress caused by the penetration of unwanted bacteria or viruses into the human body, free radicals begin to be produced more actively, acting as a silent signal for the immune system.
As a result, cells at the forefront of our immune defenses - macrophages and lymphocytes - begin to divide and fight the problem. If it's a bacterium, they'll swallow it, like Pacman the blue ghost in the popular computer game.
The bacteria will be trapped, but still alive. To fix this, free radicals are back in action.
Inside the immune cell, they are used for exactly what they got a bad reputation for: killing and destroying. The intruder is torn to pieces.
From start to finish, a healthy immune response depends on the presence of free radicals in the body.
Geneticists João Pedro Magalhães and George Church wrote in 2006: “Fire is dangerous, but people have learned to use it to their advantage. Likewise, cells appear to have been able to develop mechanisms to control and utilize [free radicals]."
In other words, it is not worth getting rid of free radicals with antioxidants.
“In this case, we will be defenseless against some infections,” emphasizes Enriquez.
Fortunately, the human body has systems that are responsible for maintaining the stability of biochemical processes.
In the case of antioxidants, the excess is removed from the bloodstream into the urine. "They are simply excreted naturally from the body," says Cleva Villanueva of the Mexico City National Polytechnic.
“The human body has an incredible ability to balance everything, so the effects [of supplementation] will be mild anyway, and we should be grateful for that,” says Lane.
We began to adapt to the risks associated with oxygen even when the first microorganisms began to breathe this toxic gas, and a simple pill cannot change what has been created over billions of years of evolution.
No one can deny that vitamin C is an essential part of a healthy lifestyle, as are all antioxidants.
But, unless these supplements are prescribed by a doctor, eating a healthy diet is still the best way to extend your life.
“Taking antioxidants is only justified when the body is actually deficient in a particular substance,” says Villanueva. "It is best to get antioxidants from foods that contain a specific set of antioxidants acting in combination."
“A diet rich in fruits and vegetables is usually very healthy,” says Lane. "Not always, but in most cases it is."
While the benefits of this diet are often attributed to antioxidants, a healthy balance of prooxidants and other nutrients are not yet known for certain.
For decades, scientists have tried to understand the complex biochemistry of free radicals and antioxidants, have attracted hundreds of thousands of volunteers to their research and have spent millions on clinical trials, but modern science has not yet offered us anything better than the advice we have known from school: eat five vegetables or fruit every day.
Alex Riley
