Lutein and lycopene loss during digestion in lab tests
What it found
In lab tests, lutein and lycopene held up through the stomach and small intestine when digestive enzymes were present, with losses of 40% and 20% only in the later jejunal stage.
Beta-carotene lost 25% early on, and red meat made lycopene and beta-carotene losses worse.
What they found
Animal and lab studies
Lutein with enzymes
In lab tests with digestive enzymes, lutein stayed stable through the stomach and duodenum. By the jejunal stage, 40% was lost, leaving 60% of the original amount.
Lycopene with enzymes
In lab tests with digestive enzymes, lycopene stayed stable through the stomach and duodenum. A loss of about 20% was seen only in the jejunal stage.
Beta-carotene with enzymes
In lab tests with digestive enzymes, 25% of beta-carotene was lost during the gastric phase, with no further loss after that.
Red meat and lycopene
In lab tests with enzymes, metmyoglobin (from red meat) caused a 12% loss of lycopene after the duodenal phase and a 19% loss after the jejunal phase.
Red meat and beta-carotene
In lab tests with enzymes, metmyoglobin caused a 50% loss of beta-carotene during the gastric phase and a further 30% loss during the duodenal phase.
Iron supplement
Ferrous sulfate, the type of iron in supplements, had no significant impact on any carotenoid level in these lab tests.
What the authors conclude
- They conclude that some chemical factors that reduce carotenoid stability in a lab emulsion model are counteracted when digestive enzymes are present.
- They say that a commonly prescribed dose of supplemental iron taken with a carotenoid-containing meal does not affect carotenoid stability.
- They advise that eating red meat with foods containing lycopene or beta-carotene is likely to reduce the amount of carotenoid available for absorption and may create carotenoid oxidation products.
How it was done
The authors wanted to understand what happens to carotenoids during digestion, since these compounds may act as antioxidants in the gut and their low absorption might partly be due to breakdown during digestion.
They mixed lutein, lycopene, or beta-carotene into a liquid meal with oil and put it through a lab model of digestion covering the mouth, stomach, duodenum, and jejunum. They tested each carotenoid with and without digestive enzymes, and with and without iron from a supplement or from red meat.
What it can’t tell you
- These are lab tests, not studies in people. They can't show what happens to carotenoids inside the human body.
- The lab model does not include absorption, so it can't show how much carotenoid actually gets into the bloodstream.
- The authors did not find oxidation products in this study, so they can't say what breakdown products form or whether they have any effects.
The paper
- Title
- Are lutein, lycopene, and β-carotene lost through the digestive process?
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Kopec RE, Gleize B, Borel P, Desmarchelier C, Caris-Veyrat C (2017). Are lutein, lycopene, and β-carotene lost through the digestive process?. Food & function. doi:10.1039/c7fo00021aFree full textPubMed 28350027DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error