Lesson 6. Infammation: When Defence Doesn’t Stand Down

1 · What have we learned so far?

We began by asking what your body needs from food. In Lessons 1 and 2, we saw that nutrients provide energy, supply materials to build and repair tissues, and help cells do their everyday work. In Lesson 3, we saw how water carries substances around the body and provides the environment for many reactions inside cells. In Lessons 4 and 5, we looked at one result of all that activity. As cells use oxygen to release energy from nutrients, they produce reactive molecules. Some of these molecules help cells send signals. Antioxidant defences help keep them in check. If those defences can’t keep up, oxidative stress can develop and cells can be damaged. So why would your body sometimes make more of these molecules on purpose?

2 · Why are we looking at inflammation now?

Imagine you nick your finger while slicing an apple. The damaged skin sends out signals that draw immune cells to the cut. Some of these cells make reactive molecules to help kill any bacteria that got in. Here, those molecules are doing a useful job as part of inflammation, the body’s local defence response. If that response keeps going, however, reactive molecules can build up and damage nearby tissue. The newly damaged cells can then send out more signals for help. That’s how inflammation and oxidative stress can keep each other going.

Food connects to this story in two ways. At the cut, it supplies the energy and materials your skin needs to repair itself. Over time, what you eat regularly can also influence some markers of ongoing inflammation. To see where food can make a difference, let’s first look at what inflammation does, why we need it, and what happens when it stays active. pubmed.ncbi.nlm.nih.gov

3 · What is inflammation, and why do we need it?

Inflammation is one way your immune system responds to injury or infection. At the cut, signals from damaged cells cause nearby blood vessels to widen. More blood flows to the area, which is why the skin can look red and feel warm. Fluid can move into the surrounding tissue, causing swelling. Meanwhile, immune cells follow chemical signals to the injury, where they help clear away damaged material and deal with any bacteria that got in. The injury itself can start this response, even if no bacteria enter the cut.

The ability to respond quickly to injury and infection helped organisms survive. A local response can help contain microbes before they spread and clear the way for repair. At the same time, skin cells at the edges begin to close the gap. That’s repair, the work of rebuilding damaged tissue. Because these processes overlap, your skin can already be closing while the area around it is still red.

So why does inflammation have such a bad reputation? We notice the sting and the swelling. We rarely notice the immune cells doing the clearing up. As the cut heals, fewer immune cells are called in, and cells called macrophages help remove debris and immune cells that have finished their job. This active winding down is called resolution. By the time you slice the next apple, you may have forgotten which finger you cut.

4 · What happens when the call for help keeps going?

Sometimes the original trigger persists. In other cases, the response itself helps keep the call for help going. Reactive molecules made by immune cells can damage nearby tissue. Those newly damaged cells can then release fresh signals that keep the immune response active. The tissue is thus being damaged while the body is still trying to repair it.

The consequences depend on where the inflammation happens and how long it lasts. In rheumatoid arthritis, persistent inflammation can damage cartilage and bone in the joints. In Crohn’s disease, repeated inflammation can contribute to scarring and narrowing of the bowel. Over many years, persistent inflammation in the colon can also increase the risk of bowel cancer. www.niams.nih.gov

5 · Where does food fit in?

The question at the heart of our orthomolecular approach is What does the body need to do its work? We eat to supply energy, grow and maintain tissues, repair damage and keep everyday processes running. At the cut, cells use energy and amino acids to rebuild tissue. They also use vitamin C to help make collagen, which gives skin much of its strength.

When we’re ill, food can play different roles. In scurvy, replacing missing vitamin C addresses the cause. In coeliac disease, removing gluten takes away the trigger for an immune reaction. And when illness makes eating difficult, getting enough energy and protein may be the immediate priority. So the role of nutrition depends on what started the problem and what the body needs now. www.niddk.nih.gov

Then there’s what we eat over months and years. A Western-style eating pattern typically includes lots of sugary drinks, refined grains and processed meats, and relatively few whole grains, pulses, vegetables and fruit. Such patterns can contribute to the risk of chronic conditions such as type 2 diabetes and cardiovascular disease. Inflammation can be part of that picture, alongside changes in blood sugar, blood pressure and blood lipids. Each of these processes helps explain a different part of the relationship between food and disease. www.who.int

6 · Omega-3 and antioxidants act at two points in the cycle

Think back to the call for help at the cut. The body can wind down that call once the immediate job is done. It can also limit the oxidative damage that might set off another call. Two examples from nutrition help explain how.

Omega-3 provides building blocks for signals that help inflammation resolve. The body can use two omega-3 fats, EPA and DHA, to make some of those signals. Sardines, herring, mackerel and salmon supply EPA and DHA directly. Algal oil can supply DHA and, depending on the product, EPA. Walnuts, ground flaxseed, chia seeds and rapeseed oil supply ALA, an essential plant omega-3. The body converts only a small share of ALA into EPA and DHA, so walnuts in your porridge and sardines on your toast give you omega-3 in different forms. ods.od.nih.gov

Antioxidant defences help limit oxidative damage. Your cells have their own systems for keeping reactive molecules in check, and some nutrients contribute to those defences. Vitamin E, found in almonds and sunflower seeds, helps protect the fats in cell membranes from oxidation. Vitamin C, found in peppers, kiwis and oranges, also acts as an antioxidant. This matters because damaged cells can release fresh signals that keep inflammation active. Omega-3 and antioxidant nutrients therefore illustrate two different parts of the cycle: winding down the response and limiting the damage that can sustain it.

7 · What could that look like on your plate?

Try oats with berries, walnuts and ground flaxseed, or a bowl of lentils, roasted peppers and sardines with an olive oil dressing. The first gives you plant omega-3. The second gives you EPA and DHA from the sardines and vitamin C from the peppers. Both are examples of meals you can build into an everyday eating pattern.

Trials of Mediterranean-style diets rich in vegetables, fruit, pulses, whole grains, nuts and olive oil have found reductions in some blood markers of inflammation. The evidence here concerns the overall pattern. Whether a change in those markers translates into fewer symptoms or a change in the course of a particular disease is a separate question. In a later lesson, we’ll look at other foods studied for their effects on inflammation and what the research tells us about each one. pubmed.ncbi.nlm.nih.gov

Your building blocks

Next Week

The cells repairing your finger can use amino acids from your lunch. But lunch went to your stomach. How did those amino acids make it all the way to your finger?