A few days of stress, poor sleep and skipped meals won’t just leave you vulnerable to catching a cold, it could put you at risk of life-changing diseases. That’s because your immune system is one of the body’s five key defence systems — immunity, stem cells, gut bacteria, blood vessels and DNA protection — and when any are weakened, it can open the door to myriad health problems. All this week we have been serialising a groundbreaking new book, Eat To Beat Disease, by U.S. doctor and scientist Dr William Li. It explains how each of the body’s defence systems work, and shows you the sometimes surprising foods that can be added to your diet to support these systems and help your body stay healthy. In today’s pullout — part of the Mail’s Good Health for Life month — he explains how to incorporate the important information given throughout this series into your diet, and pick the foods that will help you fight specific conditions and diseases. He also reveals the importance of the immune system, and the foods that can make it more effective — and those that slow it down when it runs amok and starts to cause illness itself. When it’s on top form, your immune system protects the body from any invasions by viruses, bacteria and parasites through an ingeniously designed system of pattern recognition. This allows your immune cells to identify and destroy threats while leaving healthy cells alone. It is (or should be) a system on perpetual standby, like the fire brigade, ready to leap into action when an alarm is sounded.
A healthy body automatically knows whether to turn up or turn down its immune response. Neither inactive nor overactive, it operates from a point where all forces are carefully balanced and constantly alert.
But the stresses and strains of modern life can render it weak. Obesity puts you at risk of this, as does diabetes, malnutrition (which includes an unhealthy diet, as well as insufficient food) and too much alcohol.
A weak immune system doesn’t just let rogue infections slip through the net, it can also cause it to become confused and start attacking its own harmless cells.
These exaggerated immune responses are seen in allergic reactions, where the immune system adopts an overkill response to an otherwise harmless allergen, such as pollen or a certain food. The same reaction can lead to asthma.
Immune system overactivity can also manifest as serious autoimmune diseases including type 1 diabetes, lupus (a condition causing inflammation of the joints, skin and organs), multiple sclerosis, psoriasis and rheumatoid arthritis.
These are all the result of damage to cells caused by a trigger-happy immune system viewing something innocent as a foreign invader.
Regular exercise, proper sleep, and lowering and managing your stress levels will all help your immune system stay healthy. But recent discoveries have changed our understanding of the immune system.
The study of food compounds has advanced significantly in recent years, and we know that what we eat and drink can turn the two arms of immunity — the under-performing immune system and over-functioning immune system — up or down to defend our health.
You can boost your body’s resilience with foods that support our immune defences, and foods that can calm it when it becomes overactive.
Turn to the back page to read about the specific foods that can fine-tune your immune system and help you thwart disease.
And, overleaf, discover how diet changes can be used to fight serious diseases.
Strengthen defences to tackle cancer
We have always blamed genetics, smoking, the environment, a bad diet, and other external factors for cancer.
But the truth is that, regardless of its cause, cancer only becomes a disease once malignant cells escape being destroyed by the immune system.
Normally, when the earliest signs of cancerous growths are spotted by first-responder immune cells, they send out cancer-killing cells.
Sometimes, cancer cells use camouflage to dodge this process, and wrap themselves in some friendly proteins to fool immune cells into thinking they are normal. By hiding like this, these cancer cells are able to grow.
If your immune system is weakened, cancer cells can be missed, and are able to multiply freely without fear of attack.
A staggering one in two people in the UK will develop cancer at some point in their lifetime, and its toxic treatments are often feared as much as the disease itself.
If you’ve got it, had it, or you’re worried about getting it, then it is important to shore up your defences and help your body destroy the cancer cells — or support it through treatment.
When working well, your own immunity is so powerful it can protect you against cancer. Indeed, some of the most revolutionary cancer treatments are now aimed at activating the immune system.
If you have cancer, you need to protect your immune system —especially if you receive high-dose chemotherapy and/or radiation, both of which deliver a smackdown to immune defences. If you are receiving one of the new cancer immunotherapies, which rely on your immune system to wipe out cancer cells, it’s critical to get it into prime shape.
The food you eat will play a role in this goal. You’ll get extra cancer-fighting support if you call in your body’s other defence systems, too.
That’s because all cancers depend on weaknesses in angiogenesis (the formation of blood vessels) to grow; have rogue stem cells that need to be destroyed; are riddled with DNA mutations; and can be wiped out by your body’s immune system defences.
I recommend that you eat:
Foods with ‘anti-angiogenic’ properties — rogue angiogenesis feeds the cancer — that can starve a tumour by cutting off its blood supply, such as tomatoes and blueberries.
Foods that help get rid of tenacious cancer stem cells, such as purple sweet potatoes, which improve the odds that the cancer won’t come back following treatment.
A diet that activates the immune system (see back page) and foods that promote a healthier microbiome (the community of bacteria in your gut), which can assist in cancer control and elimination (look out for these in tomorrow’s pullout).
Foods that protect DNA (oysters, oyster sauce, or herbs) so your body can both shield you and repair any errors in your DNA that could lead to cancer.