The skin is the ultimate barrier to the human body, protecting it from mechanical damage, But accidents happen. We may trip while jogging or climbing up the stairs and sustain a wound of skin tearing. Wounds can be very painful, and the sight of blood oozing out doesn’t help. But our body is a miracle, and this post pays tribute to its healing powers. I will outline the key stages of wound healing, highlighting the critical role played by our immune system. Then I will conclude with some remarks on the type of diet that supports a healthy immune system.
Clotting
The process of wound healing starts almost immediately after the injury. First, blood leaks out of the body, then blood vessels constrict to restrict the blood flow. Within minutes, the blood will start to clot to stop the bleeding. A type of blood cells known as platelets are responsible for clotting. The clot will dry up and form a scab to protect the tissue underneath from germs. The redness and swelling that follows the scab formation is normal, and is due to the dilation of local blood vessels to allow immune cells to enter the damaged site.
Fighting Infections
Once the scab forms, your body’s immune system will start to protect the wound from infection. It will signal blood vessels to open in the wound area, so oxygen and nutrients can be brought to the wound. Oxygen is essential for healing, but the right balance of oxygen is also important — too much or too little and the wound won’t heal correctly.
The first responders are a type of white blood cells known as neutrophils. They remove foreign material and bacteria from the wound. The next wave of white blood cells to arrive at the scene cells are the macrophages, which coordinate the wound healing response. Macrophages can be thought of as the immune system’s “construction workers.” They clear the damaged site of debris in order to lay the foundations for tissue repair. The repair process will normally take about 2 to 5 days, somewhat longer for a deeper or larger wound.
Tissue Repair
Over the next month or so, the body will repair broken blood vessels and grow new tissues. Red blood cells help create collagen essential to tissue growth. Collagen is the tough, white fibers that form the foundation of new tissue. Gradually, the wound starts to fill in the new tissues which are called granulation tissue, and new skin will begin to form over this tissue. As the wound heals, the edges pull inward, and the wound gets smaller. T cells (another type of white blood cells) are particularly active during this stage of tissue repair, producing growth factors and cytokines, small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells. Incidentally, around this time, you will feel that the wound area itches. This sensation is normal. The itch is partly a result of the body’s inflammatory response due to the release of histamines which cause blood vessels to dilate, and partly to new tissues growing to replace damaged ones.
Scar Formation
As the healing continues, a scar will form where the scab falls off. The scar will be smaller than the original wound and feel firmer. Given time, the scar will fade and may disappear completely, though I should that some scars can take as long as 2 years to fade, and some may never go away completely.
On Diet and the Immune System
As the above makes clear, the body has an amazing ability to repair itself after injury. The immune system and some critical proteins are behind this invisible miracle. One of the most important class of proteins are cytokines. They comprise different types of proteins that tell immune cells where to go and what to do to keep your immune system functioning correctly. Following a diet with lots of anti-inflammatory foods is a key way to boost the cytokine status of our bodies.
The immune system itself consists of five parts, of which white blood cells (themselves made up of many types) play a crucial role as we have seen. White blood cells are made in your bone marrow (the spongy tissue inside your bones). A diet rich in protein (lean meats), fish, beans, nuts, milk, eggs will help to keep your bone marrow, and immune system in tip-top condition, underscoring the critical role nutrition plays in maintaining physical health.