Tomato products and lycopene for reducing blood pressure Original paper

Tomatoes are a rich source of lycopene (and other carotenoids), flavonoids, and other nutrients that may exert antihypertensive effects, potentially by reducing oxidative stress and increasing nitric oxide availability. Although a previous meta-analysis suggested that tomato products and lycopene supplementation may reduce blood pressure,^[1] different types of products (e.g., raw tomato, processed tomato, and lycopene supplements) were grouped together in the analyses. This network meta-analysis separately examined the effects of different tomato preparations on blood pressure.

This network meta-analysis of randomized controlled trials examined the effects of different tomato preparations, as compared to placebo or active control, on systolic (8 trials; 617 participants) and diastolic (7 trials; 501 participants) blood pressure in adults with or without hypertension or prehypertension.

The tomato preparations consisted of the following:

• Standardized tomato extract (STE), with 10–15 milligrams of lycopene per day
• Low-dose standardized tomato extract (LSTE), with ≤5 milligrams of lycopene per day
• High-dose standardized tomato extract (HSTE), with ≥15 milligrams of lycopene per day
• Tomato-rich diet (Tdiet), with an unknown amount of lycopene
• Lycopene-free tomato extract (FreeLYC)
• Synthetic lycopene (LYC)

The intervention durations ranged between 1.3 and 24 weeks, with most interventions lasting 4–9 weeks.

The STE treatment significantly reduced systolic blood pressure by 5.9 mmHg, but the effect on diastolic blood pressure (−3.5 mmHg) was not statistically significant. These effects on systolic and diastolic pressure were more pronounced and statistically significant for both outcome measures in individuals with hypertension.

Although only the effect of STE on systolic blood pressure reached statistical significance, LSTE, HSTE, Tdiet, and FreeLYC also seemed to improve systolic blood pressure, although the effects did not reach statistical significance.

Although the results are promising, there was a high risk of bias for 55% of the trials and some methodological concerns for 36% of the trials included in the meta-analysis. This reduces our confidence in the results.