People who eat lots of fruit and vegetables tend to live longer, we know that.
But is that because of the fruit and vegetables themselves – or because those people also tend to exercise more, smoke less, drink less, sleep better and generally look after themselves?
This is why I am always slightly sceptical when I read yet another headline telling us that one particular food is going to save our lives and help us live for ever in perfect health (especially if it is a paper written by a company marketing that particular food).
But a new study on the humble tomato really caught my eye.
This wasn’t simply researchers asking thousands of people what they ate and then looking years later to see who got ill – as most nutritional studies are done. They actually carried out a randomised-controlled trial to see what effect eating tomatoes had on a specific health marker.
The study, by the Italian National Institute of Gastroenterology, took 79 people who had fatty liver disease and allocated them to two groups: one had to eat 200g of raw tomatoes every day plus 50g of tomato sauce, the other group had to avoid tomatoes completely, for six weeks.
Fatty liver matters. It is now incredibly common and is closely linked to excess weight, insulin resistance and type 2 diabetes.
For many people it causes no immediate symptoms, which is part of the problem – you can have large amounts of fat accumulating inside your liver and feel fine. But in others it progresses to inflammation, scarring, cirrhosis and even liver cancer.
Because lycopene (a compound found in tomatoes that may change the way the liver handles fat) is fat soluble, eating cooked tomatoes with olive oil may boost absorption even further
The researchers measured fat in the liver using a FibroScan, which gives a measurement known as Cap (controlled attenuation parameter). Put simply: the higher the number, the more fatty the liver.
And after just six weeks there was a clear difference: the liver-fat reading dropped by 35 points in the tomato eaters, compared with 18 points in those avoiding tomatoes, reported the journal Nutrients.
Interestingly, liver fat also fell a little in the group avoiding tomatoes, perhaps because simply taking part in a health study made them improve other parts of their diet or lifestyle.
But this is the bit I really find important. The tomato eaters hadn’t simply gone on a diet and lost loads of weight. In fact, their body weight barely changed.
There were no significant differences between the groups in BMI, waist circumference, total body fat or visceral fat (the toxic fat that can build up around your organs). There were also no dramatic changes in their cholesterol, blood sugar or standard liver blood tests.
So this wasn’t simply a case of people eating tomatoes, losing weight and therefore losing fat from their liver. Something more specific appeared to be happening in the liver itself.
The researchers think compounds in tomatoes, particularly lycopene and beta-carotene, may change the way the liver handles fat: reducing how much new fat it makes, limiting how much it takes up and helping to burn more of it.
Science purists will quite rightly point out that one small study involving 79 people over just six weeks does not prove that tomatoes are a treatment for fatty liver. But this is where I think common sense matters.
This is some of the best evidence we have on the specific benefits of eating tomatoes. And unlike a new drug, there’s virtually no downside to acting on this evidence.
Tomatoes are cheap, nutritious and research has repeatedly linked them with better health.
One 2021 study of more than 100,000 US adults, followed for an average of 17 years, found that moderate consumption of tomatoes was associated with a lower risk of dying overall and from cardiovascular disease specifically.
And a 2025 analysis of 119 studies showed higher tomato intake was associated with an 11 per cent lower risk of dying from cancer. Some studies have suggested particular protection against prostate cancer.
Of course, none of this proves that tomatoes were responsible – again, these were all observational studies. More research into the benefits of tomatoes is needed, but I am not going to wait for a randomised controlled trial involving 10,000 people before changing what I put on my plate.
So why might tomatoes help with conditions beyond fatty liver?
As well as affecting fat cells, the lycopene and beta-carotene, along with polyphenols and vitamin C in tomatoes, seem to dampen inflammation and protect our cells against oxidative stress. This is the damage caused when unstable molecules known as free radicals build up. Both processes are involved in conditions ranging from heart disease and cancer to the ageing of our skin.
But we do not know whether lycopene is the star ingredient or whether the benefits come from these compounds working together. That matters because lycopene supplements are widely sold. Yet the evidence I have discussed is mainly about eating tomatoes, not taking lycopene pills. So I would advise eating whole tomatoes rather than popping a supplement pill.
The Italian researchers deliberately used both raw tomatoes and tomato sauce because they offer slightly different benefits.
Raw tomatoes preserve more vitamin C, while cooking makes lycopene easier to absorb. And because lycopene is fat soluble, eating cooked tomatoes with olive oil may boost absorption even further.
So my advice is simple: eat both and eat them daily, especially if you are overweight or have prediabetes or diabetes, because you are at a greater risk of developing fatty liver disease.
And that’s exactly what I am going to do: more raw tomatoes in salads or as a snack – and more cooked tomatoes with olive oil in pasta sauces, soups and stews.
Because although this study was only done in people who already had fatty liver disease, there is no obvious reason to think the same mechanisms would not also help to reduce the chances of developing it in the first place and to reduce fat elsewhere in the body.
Will I be prescribing tomatoes in A&E? Of course not. But I’d rather see packets of tomatoes for sale in hospital vending machines than just crisps and chocolate. And I will be advising my patients and family (and myself) to eat more tomatoes after reading this study. Sometimes the healthiest changes really are the simplest.
@drrobgalloway
You must be logged in to post a comment Login