Free radicals and antioxidants

Free radicals and antioxidants play critical roles in the body’s biology, particularly in the balance between oxidative stress and protection against it. Here’s a breakdown of how they work:

### **Free Radicals**
– **What are they?**
Free radicals are unstable molecules with one or more unpaired electrons. These molecules are highly reactive because they seek to stabilize themselves by stealing electrons from other molecules in the body.

– **How are they formed?**
They are produced as by-products of normal cellular metabolism, especially during the process of **oxidation**. This can happen in the mitochondria when the body uses oxygen to produce energy, but free radicals can also be formed due to exposure to external sources like pollution, cigarette smoke, UV rays, and certain chemicals.

– **Common types of free radicals:**
– **Reactive Oxygen Species (ROS):** Examples include superoxide (O₂⁻), hydroxyl radicals (OH), and hydrogen peroxide (H₂O₂).
– **Reactive Nitrogen Species (RNS):** Examples include nitric oxide (NO) and peroxynitrite (ONOO⁻).

– **Why are they harmful?**
Free radicals can damage essential biomolecules such as DNA, proteins, and lipids by stealing electrons, a process known as **oxidative stress**. This can lead to cell dysfunction, aging, and various diseases such as cancer, cardiovascular diseases, and neurodegenerative conditions.

### **Antioxidants**
– **What are they?**
Antioxidants are molecules that neutralize free radicals by donating electrons without becoming unstable themselves. They act as a defense mechanism to reduce oxidative damage in the body.

– **How do they work?**
Antioxidants can safely interact with free radicals and terminate the chain reaction before vital molecules are harmed. They essentially donate electrons to stabilize the free radical without becoming reactive themselves.

– **Types of antioxidants:**
1. **Endogenous antioxidants** (produced by the body):
– **Glutathione**
– **Superoxide dismutase (SOD)**
– **Catalase**
– **Coenzyme Q10**

2. **Exogenous antioxidants** (obtained from the diet):
– **Vitamin C**
– **Vitamin E**
– **Beta-carotene**
– **Polyphenols** (found in tea, coffee, fruits)
– **Flavonoids** (found in fruits, vegetables, chocolate)

### **The Balance between Free Radicals and Antioxidants**
In a healthy state, there is a balance between free radicals and antioxidants. When free radicals overwhelm the body’s ability to regulate them, **oxidative stress** occurs, which can lead to damage. On the other hand, antioxidants help maintain balance by neutralizing these free radicals, protecting cells and tissues from damage.

### **Key Points in How They Work Together:**
– **Free radicals** can cause cell damage by taking electrons from key molecules.
– **Antioxidants** donate electrons to free radicals to neutralize them, preventing further damage.
– **Oxidative stress** occurs when free radical production exceeds the neutralizing capacity of antioxidants, leading to potential harm.

In summary, free radicals are highly reactive molecules that can cause cellular damage, while antioxidants serve as protective agents to neutralize these molecules, helping to prevent the onset of various diseases and the aging process.