Scientists have identified the benefits of tomatoes in liver disease

Daily consumption of fresh tomatoes and tomato sauce was associated with a more pronounced decrease in liver fat accumulation in adults with metabolically associated steatotic liver disease. This is the conclusion reached by Italian scientists based on the results of a six-week study. This was reported by the magazine Nutrients.

How the research was conducted

The POMOSANO study involved 79 people aged 18 to 65 years with metabolically associated steatotic liver disease, or MASLD. Previously, this condition was commonly referred to as non-alcoholic fatty liver disease. With it, excess fat accumulates in liver cells, and the risk of the disease increases with insulin resistance, type 2 diabetes, lipid metabolism disorders, and other metabolic problems.

In all participants, fat accumulation in the liver was confirmed using a controlled ultrasound attenuation parameter, or CAP. This indicator is measured using a FibroScan device and allows noninvasively assessing the degree of steatosis. The study included people with a body mass index of no more than 30. Participants with other liver diseases or excessive alcohol consumption were excluded.

The volunteers were randomly divided into two groups. The first group included 42 people who consumed 200 grams of fresh tomatoes and 50 grams of tomato sauce daily for six weeks. Another 37 participants completely excluded tomatoes from the diet.

Both groups received the same dietary recommendations. The participants were also asked not to change their usual level of physical activity and lifestyle. Tomatoes and sauce came from the same certified manufacturer, so that the composition of the products remained as uniform as possible throughout the experiment.

Before and after the study, the researchers assessed body weight, waist circumference, body composition, blood counts, liver stiffness, and severity of steatosis. The specialists who performed liver examinations and laboratory tests did not know which group each participant belonged to.

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How has the liver fat index changed?

In six weeks, the CAP index decreased in both groups. However, among people who consumed tomatoes and tomato sauce daily, the decrease was more pronounced. The median decrease was 35 dB/m in the tomato group versus 18 dB/m in the control group. After accounting for the initial differences, the adjusted difference in CAP dynamics between the groups reached 26.63 dB/m. The result was statistically significant.

At the same time, body weight, body mass index, waist circumference, total and visceral fat did not significantly change among the participants. This indicates that the decrease in CAP was not accompanied by significant weight loss.

At the same time, the researchers found no significant differences between the groups in liver stiffness and the FIB-4 index, which is used to pre-assess the risk of fibrosis. Glucose, cholesterol, inflammation, liver enzymes, and most other biochemical parameters also did not change.

Thus, the effect of the study was mainly limited to the steatosis index. The authors did not establish that eating tomatoes reduces fibrosis, restores liver function, or prevents the development of cirrhosis.

Why tomatoes could affect the liver

The researchers suggested that the possible effect is related to the biologically active substances contained in tomatoes. These include lycopene, beta-carotene, polyphenols, and other compounds with antioxidant and anti-inflammatory properties.

Lycopene may be involved in the regulation of fat metabolism, oxidative stress, and inflammatory processes. At the same time, after heat treatment, it becomes more accessible for assimilation. For this reason, the scientists combined fresh tomatoes with tomato sauce.

However, the concentration of lycopene and other carotenoids in the blood of the participants was not measured. The study therefore does not allow us to determine which compound caused the observed changes. The combined effect of several components of tomatoes cannot be excluded.

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Why can't the conclusions be considered final yet

Despite the randomized design, the study had a number of significant limitations. It was held in one center, lasted only six weeks and included 79 people. Most of the participants were men, and people with a body mass index above 30 were not included in the experiment.

The participants knew which group they were in, and dieting was assessed primarily based on their own reports. The amount of fat in the liver was determined indirectly by CAP, rather than by biopsy or magnetic resonance imaging.

In addition, the CAP decreased not only in those who consumed tomatoes, but also in the control group. This could be due to general dietary recommendations, changes in the participants' eating behavior, or natural fluctuations in the indicator.

The authors also did not determine whether the effect persists after the end of the six-week period and whether it can further affect the risk of inflammation, fibrosis or cirrhosis. The clinical significance of the reported decrease in CAP has yet to be determined.

The researchers consider the results to be the basis for conducting larger and longer trials. So far, the work shows only that the daily consumption of 200 g of fresh tomatoes and 50 g of tomato sauce may be associated with a decrease in one of the indicators of steatosis in individual patients with MASLD.

The results cannot be transferred to all people or considered as proof that tomatoes are able to cure fatty liver disease on their own. Patients with liver diseases should not replace their prescribed treatment or change their diet without consulting a doctor.