Research from Hong Kong published in 2025 showed that olive oil and walnuts strengthen special immune cells that recognize and destroy tumor cells even before they develop into cancer.
What is actually happening in the body?
You can imagine our immune system as a small but extremely efficient army. Among its fastest soldiers are gamma-delta T-cells. These are special white blood cells that patrol the body looking for suspicious cells. When they find them, they destroy them. These cells act as your personal security guard, working 24 hours a day to ensure no invaders enter your body.
Scientists from the University of Hong Kong (HKUMed) found that these cells have their own fuel, which is not sugar or coffee, but the fat we eat.
In the research, they tested two types of fatty acids:
- Oleic acid (OA) – this is a healthy, unsaturated fat found in olive oil, avocado, walnuts, almonds, and sunflower seeds.
- Palmitic acid (PA) – this is a saturated fat found in butter, fatty meat, cheese, and especially palm oil, which is often hidden in industrial biscuits and chocolate bars.
The result was surprising... When gamma-delta cells were fed with oleic acid, they became stronger, more resilient, and more effective at destroying tumors. Their mitochondria—the tiny power plants inside cells that generate energy—worked steadily, like a well-oiled machine.
On the other hand, cells exposed to palmitic acid began to visibly die off. Their internal energy literally collapsed, inflammation appeared, and the environment around the cells became ideal for the spread of cancerous changes.
Professor Tu Wenwei, the head of the research, stated: Foods rich in oleic acid, such as olive oil and avocado, can improve immune surveillance and help the body fight cancer better.
This means that the fat we consume is not just a source of energy, but also directly influences how effectively our body detects and destroys dangerous cells.
Why our grandmothers knew more than they thought
Our ancestors knew, without laboratories, what science is confirming today: a spoonful of olive oil on an empty stomach and a handful of walnuts a day keep the doctor away.
In the past, people used olive oil not just for cooking, but also as a remedy for the skin, digestion, and the immune system.
Walnuts have always been a symbol of strength and wisdom, and even the ancient Romans believed they strengthen the brain.
In 2023, the Harvard School of Public Health published data showing that people who consume 20g of nuts daily live on average 3 years longer than those who do not eat nuts.
The Spanish PREDIMED study showed that 1 to 2 tablespoons of olive oil daily reduces the risk of stroke by 30% and improves immune response after just 12 weeks of regular use.
In 2024, Italian researchers from Parma found that oleic acid reduces the activity of inflammatory genes by up to 40% in people with weakened immune systems.
Even though we are talking about modern research, we keep returning to old, simple solutions.
What is immunometabolism and why is it important
The word immunometabolism may sound complicated, but it means something simple: it is the science that studies how food affects the functioning of our immune system. It matters what kind of fuel we give our immune system. If you give it the right fuel, it works well; if you give it the wrong, it gets tired, blocks, or even attacks its own cells.
According to the journal Nature Immunology from 2025, as many as 65% of immune disorders stem from improper nutrition—mainly due to excess saturated fats, sugar, and artificial additives.
This is why researchers from Hong Kong went a step further and examined how dietary changes can support immunotherapy. Immunotherapy is becoming an increasingly accepted modern way of treating cancer, where doctors help the immune system attack the tumor itself. The result of the research was that a combination of medication and a diet rich in oleic acid increases therapy effectiveness by up to 25% – a huge leap forward.
How to strengthen the immune system
The good news is you don’t need special capsules, powders, or supplements for this. Small changes in your daily diet are enough. If you want to take the first step, try the following:
- Instead of butter for baking, use a tablespoon of extra virgin olive oil.
- Swap industrial snacks for a handful of walnuts, almonds, or sunflower seeds.
- Add avocado to salads or make a simple spread (mash avocado with a spoonful of lemon juice and a pinch of salt).
- Instead of cream, use plant milk or homemade cashew cream (blend cashews with a bit of water).
Such changes are not only healthy but also cheap. If every family replaced 100g of butter with olive oil every week, this would mean 1.3 million liters less saturated fat per year, which, according to WHO estimates, would reduce the incidence of cardiovascular disease by 10%.
How walnuts work – more than just healthy fat
Walnuts are not only a source of oleic acid—they also contain alpha-linolenic acid (ALA), which the body converts into omega-3 fatty acids.
According to a study by Yale University from 2022, just 7 walnuts a day improve brain function and memory in adults by 19% after two months of regular consumption. Walnuts also contain melatonin, the natural sleep hormone, so they help regenerate the immune system overnight.
Ancient healers often recommended walnuts to people after illness and operations, because “they nourish the blood and soul.” Today we would say: they regenerate cells and reduce oxidative stress, as modern measurements confirm. Many studies have noted a decrease in oxidative markers by 15–25% in just 4 weeks.
Why not all olive oil is the same
When choosing olive oil, quality is crucial. Extra virgin olive oil contains the most oleic acid (over 75% of all fats), so it is the best choice. You don’t need to heat the oil to boiling—use it cold or lightly warmed, because at high temperatures, beneficial substances start to break down. Interesting: a Spanish study from 2021 showed that just 1 tablespoon of cold-pressed olive oil daily reduces bad LDL cholesterol by 12% in 6 weeks.
If you store olive oil in a dark bottle and at room temperature, it maintains its quality for up to 18 months. In the light or in plastic, however, beneficial substances start to degrade after just 3 months.
Food as the medicine of the future
Scientists predict that in the next decade, diet will become part of standard therapy for treating cancer and chronic diseases. The European Research Agency already estimated in 2025 that proper nutrition can prevent up to 30% of all cancers—more than 2 million lives every year worldwide.
But beware! This does not mean we should eat only oil and walnuts. As with all natural remedies, the key is moderation and balance. Too much fat, even healthy fat, can overburden the liver. It is enough for healthy fats to make up 25 to 30% of daily caloric intake, which means about 2 tablespoons of olive oil and a handful of nuts a day.
How each of us can make a difference
Even if it seems insignificant, every purchase we make has an impact. If you choose olive oil instead of palm oil, you benefit not only yourself but also the environment. Palm oil is responsible for as much as 8% of global deforestation, meaning thousands of hectares of tropical forests are lost each year.
So, with every liter of olive oil instead of palm oil, we take a step towards a cleaner planet—and at the same time, a stronger immune system.
Small spoon, big effect
In a world that is ever more artificial and fast, nature quietly reminds us that it still holds all the answers to our everyday problems. Olive oil, walnuts, almonds, and avocados are not just a passing fad. They are proven powerful tools for strengthening the body, mind, and immune system. And most importantly: all this is within easy reach—without a prescription or a laboratory.
So, next time you cook, try a spoonful of olive oil instead of butter, and eat a handful of walnuts instead of chips. Your body will be grateful, and your immune system will function better.
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