Tomato compounds reached the bloodstream in 11 adults — but more than 99% arrived in a changed form

Tomatoes contain steroidal alkaloids, including alpha-tomatine and related compounds. They are much less familiar than lycopene, and researchers still do not know whether they explain any of the health effects associated with tomato-rich diets. A pharmacokinetic study published in The American Journal of Clinical Nutrition on 27 October 2026 asked a narrower first question: after people drink tomato juice, do these compounds enter the blood, when do they peak, and what form are they in?

Eleven healthy adults — six men and five women — avoided tomatoes for two weeks, then drank 505 g of tomato juice with a standard breakfast. Blood was collected 11 times over the next 12 hours. On average, 9.7% of the alkaloids in the juice appeared in plasma either intact or as measured metabolites, although the estimate varied widely between people, from 2.4% to 17.9%. More than 99% of what circulated was made up of metabolised products rather than the original compounds from the juice.

The total concentration peaked after an average of 8.9 hours and was still above baseline at 12 hours, so the authors say their absorption estimate may be low. This was a mapping study, not a test of benefit: it had 11 participants, one tomato-containing meal and no placebo group, and it measured compounds in blood rather than health outcomes. Its useful result is a trail for future trials — evidence that tomato alkaloids are absorbed and extensively transformed, not evidence that drinking more tomato juice prevents disease.