Formed Through Natural Human Physiological Processes
Free radicals may be formed through natural human physiological processes as well as from the environment. They may be the result of diet, stress, smoking, alcohol, exercise, inflammation, drugs or exposure to sunlight and air pollutants. While there are many types of free radicals that can be formed, the most common in aerobic (oxygen breathing) organisms are oxygen free radicals, often referred to as Reactive Oxygen Species (ROS), which include superoxides, hydroxyl anions, hydrogen peroxide, and singlet oxygen.
A free radical is an atom or group of atoms that has an unpaired electron and is therefore unstable and highly reactive. An atom’s chemical behavior is determined by the number of electrons in its outermost shell. When the outermost shell is full, the atom is stable and tends not to engage in chemical reactions. When, however, the outermost shell is not full, the atom is unstable. It will try and stabilize itself by either gaining or losing an electron to either fill or empty its outermost shell or it will share its electrons by bonding with another atom that is also looking to complete its outer shell. It is not uncommon for an atom to complete its outer shell by sharing an electron with another atom and forming a bond.
Free Radicals and Antioxidants
Free radicals form when one of these weak bonds between electrons is broken and an uneven number of electrons remain. This means the electron is unpaired, making it chemically reactive. It will now try and steal an electron from a neighbouring molecule to stabilize itself.
Once a free radical form and it succeeds in gaining another electron from a nearby molecule, it leaves its victim short an electron and has now made this new molecule a free radical, which will, in turn, try and steal an electron as well. The result is what we call a free radical cascade, an enormous chain reaction of free radicals that quickly wreaks havoc on living tissue. It is estimated that the chain reaction can trigger 6.023 x 10 21 billion molecules to react per second!
- Damage DNA, RNA, cell membranes, proteins
- Cause cell death and aging
- Linked to every neurological disease:
- Neurological disorders
- Inflammatory disorders
Benefits of Free Radicals (ROS)
- Signal Transduction
- Activation of Transcription Factors
Free Radical FAQ’s
It is hard to watch television without seeing at least one commercial that promises to fight aging with antioxidants. Antioxidants are molecules that prevent the oxidation of other molecules. Antioxidants are chemicals that lessen or prevent the effects of free radicals. They donate an electron to free radicals, thereby reducing their reactivity. What makes antioxidants unique is that they can donate an electron without becoming reactive free radicals themselves.
No single antioxidant can combat the effects of every free radical. Just as free radicals have different effects in different areas of the body, each antioxidant behaves differently due to its chemical properties. In certain contexts, however, some antioxidants may become pro-oxidants, which grab electrons from other molecules, creating chemical instability that can cause oxidative stress.
1) Molecular hydrogen size
H2 is the smallest antioxidant in existence. Other antioxidants such as Vitamin C or Vitamin E are very large molecules compared to H2 and need to go through our digestive tract, absorbed in our intestines, travel through our blood, and enter into our cells before they can eliminate free radicals.
H2 is so small that it can penetrate through the stomach lining to begin acting inside cells immediately. H2 is also in a gaseous state, so it basically floats through cells (rapid diffusion) and performs its function as an antioxidant undeterred by the normal mechanisms that prevent other antioxidants from moving freely through the body. H2 can also cross the Blood-Brain-Barrier easily due to its small size whereas other antioxidants have a difficult time getting through or can’t get through at all. The brain is highly susceptible to oxidative stress because it consumes 20% of the oxygen we breathe despite being only 2% of our body’s weight. So it is very important to protect the brain with antioxidants since it is especially vulnerable.
2) Molecular hydrogen selectivity
H2 is selective and targets only hydroxyl radicals. This is a key benefit because H2 only eliminates the harmful free radicals but does not directly affect useful free radicals such as hydrogen peroxide or nitric oxide. As previously mentioned, hydrogen peroxide is used by the immune cells to kill bacteria, and nitric oxide is a signaling molecule that helps open and close blood vessels that divert blood to different areas of the body. Other antioxidants are not selective but rather neutralize any free radical in their vicinity. Non-selective free radical elimination may disrupt the balance of free radicals to antioxidants inside the cells leading to a negative effect on the body
Another antioxidant enzyme is Glutathione Peroxidase (GPX). Two GPXs convert one Hydrogen Peroxide into two molecules of water. During this reaction the two GPXs bond together to form Glutathione Disulfide (GDS). GDS needs be recycled by another enzyme to convert back into 2 GPXs ready to take on more Hydrogen Peroxide molecules. This means that GPX is not always readily available and there’s a limit to its function as an antioxidant.
This two-step process of eliminating free radicals inside the cells is crucial for the health of cells. If there’s not enough Superoxide Dismutase and Glutathione Peroxidase available, Superoxide Anion and Hydrogen Peroxide can build-up in our cells. These free radicals themselves may not be that bad, but they react with each other to form a deadly free radical, the Hydroxyl Radical. Depending on diet, lifestyle, and environment, cells can end up creating more free radicals than antioxidant enzymes can handle. As we age antioxidant enzymes dwindle naturally. When excess free radicals form inside our cells, it may result in serious consequences for health.
Free radicals are constantly produced in mitochondria.
Mitochondria are responsible for producing energy in the form of ATP (currency of energy in cells), but they also produce free radicals as a toxic by-product. Oxygen is critical in driving energy production. Unfortunately, 2-5% of the oxygen utilized in energy production converts into Free Radicals called Superoxide Anions.
Antioxidants protect our cells from free radical damage
Within our cells there are antioxidant enzymes such as Superoxide Dismutase that neutralizes a Superoxide Anion and converts it into Hydrogen Peroxide. Hydrogen Peroxide is a weak free radical that is useful in cells. The immune system uses Hydrogen Peroxide to kill bacteria and to signal to the rest of the immune system if there is an injury to tissue. Typically when acute H2O2 (Hydrogen Peroxide) is generated, this signals to our white blood cells to move to the damaged area.
Oxidative stress occurs when an oxygen molecule splits into single atoms with unpaired electrons, which are called free radicals. Electrons like to be in pairs, so these atoms, called free radicals, scavenge the body to seek out other electrons so they can become a
pair. This causes damage to cells, proteins and DNA.
These substances include fried foods, alcohol, tobacco smoke, pesticides, air pollutants, and many more. Free radicals can cause damage to parts of cells such as proteins, DNA, and cell membranes by stealing their electrons through a process called oxidation.
Understanding free radicals requires a basic knowledge of chemistry.
Atoms are surrounded by electrons that orbit the atom in layers called shells. Each shell needs to be filled by a set number of electrons. When a shell is full; electrons begin filling the next shell.
If an atom has an outer shell that is not full, it may bond with another atom, using the electrons to complete its outer shell. These types of atoms are known as free radicals. Atoms with a full outer shell are stable, but free radicals are unstable and in an effort to make up the number of electrons in their outer shell, they react quickly with other substances.
When oxygen molecules split into single atoms that have unpaired electrons, they become unstable free radicals that seek other atoms or molecules to bond to. If this continues to happen, it begins a process called oxidative stress. Oxidative stress can damage the body’s cells, leading to a range of diseases and causes symptoms of aging, such as wrinkles.
To put it in simple terms, a free radical is an incomplete molecule that is off-balance. In order to regain its balance it needs to “steal” an electron from another nearby molecule. It does so through a process called oxidation. The damaged molecule becomes a new unstable free radical in need of an electron. This chain reaction, or free radical cascade, is spreading more and more rapidly. It generates disorder within the molecules of our body.
Sometimes this phenomenon can gain momentum and get out of control. As we age, and if we do not get enough antioxidants,
this is more likely to occur.