Researchers compared how much iron your body can actually absorb from roselle (a plant with red flowers) and avocado leaves and seeds in both fresh and dried forms. They also checked for substances that might block iron absorption. The study found that fresh roselle leaves have lots of iron, but they also contain high levels of compounds that could be harmful if eaten in large amounts. Avocado leaves, roselle calyces (the cup-shaped part of the flower), and dried roselle leaves were the safest choices with good amounts of usable iron and no concerning levels of blocking substances.

The Quick Take

  • What they studied: How much iron from roselle and avocado plants your body can actually use, and whether anything in these plants blocks iron absorption.
  • Who participated: This was a laboratory study analyzing plant samples in triplicate (tested three times each). No human participants were involved—researchers measured the chemical content of different plant parts.
  • Key finding: Fresh roselle leaves contained the most iron (15.71 mg per 100 grams), but had unsafe levels of protective plant compounds. Avocado leaves, roselle calyces, and dried roselle leaves offered good iron amounts that your body could use, with safe levels of all blocking substances.
  • What it means for you: If you’re considering these plants as iron sources, avocado leaves and roselle calyces appear to be safer choices than fresh roselle leaves. However, these are not common foods in most diets, and you should consult a healthcare provider before using plant leaves as iron supplements.

The Research Details

Researchers collected samples of roselle leaves, roselle calyces (the flower cup), avocado leaves, and avocado seeds in both fresh and dried forms. They tested each sample three times to ensure accuracy. Using standard laboratory methods, they measured the amount of iron in each sample and identified nutrients that help iron absorption (like vitamin C and protein) and substances that block iron absorption (like calcium, phytates, oxalates, and tannins). They used mathematical calculations called molar ratios to predict whether blocking substances would actually prevent iron absorption in your body. All the data was analyzed using statistical software to find meaningful differences between samples.

Understanding which plant parts contain usable iron is important because iron from plants is harder for your body to absorb than iron from meat. Knowing which blocking substances are present helps predict whether eating these plants would actually help with iron intake. This research approach combines chemical analysis with absorption prediction, giving a more complete picture than just measuring iron content alone.

This is a controlled laboratory study with repeated measurements, which increases reliability. The researchers tested each sample three times and used standard scientific methods. However, this is laboratory analysis only—it doesn’t show what actually happens when people eat these plants. The study was published in a peer-reviewed nutrition journal, suggesting it met scientific standards. The main limitation is that lab results don’t always match real-world digestion in human bodies.

What the Results Show

Fresh roselle leaves had the highest iron content at 15.71 mg per 100 grams, followed by fresh avocado leaves and seeds at 13.47 mg per 100 grams. Dried forms had less iron: dried roselle leaves had 8.16 mg, dried avocado leaves had 4.47 mg, and dried avocado seeds had only 2.47 mg per 100 grams. Fresh avocado leaves contained the most protein (13.82%), while fresh roselle leaves had the most beta-carotene (a vitamin A precursor). Both fresh avocado and roselle leaves had high vitamin C levels (over 30 mg per 100 grams), which helps your body absorb iron. Calcium levels were low in all samples (under 80 mg per 100 grams), which is good because calcium can block iron absorption. The blocking substances (phytates and oxalates) were at safe levels in most samples and wouldn’t significantly prevent iron absorption based on mathematical calculations. However, fresh roselle leaves contained concerning levels of total phenolic compounds—protective plant substances that in high amounts could be harmful with regular consumption.

Tannins, phytates, and oxalates were all below levels considered potentially harmful in all samples. Only fresh avocado seeds showed iron inhibition from phytates, and this was mild. The researchers found that avocado leaves, roselle calyces, and dried roselle leaves offered the best combination of good iron content with safe antinutrient levels. Dried forms generally had lower iron content than fresh forms, suggesting some iron may be lost during drying.

This study adds to existing knowledge about plant-based iron sources by comparing multiple plant parts and forms. Previous research has shown that plant-based iron is less available than meat-based iron, and this study confirms that blocking substances matter. The finding that fresh roselle leaves have high phenolic compounds aligns with other research showing that some protective plant compounds can be problematic in large amounts.

This study only measured iron content and blocking substances in a laboratory—it didn’t test actual iron absorption in human bodies. Real digestion is complex and involves many factors not captured in lab analysis. The study didn’t specify exact sample sizes or provide detailed information about where plants were sourced or how they were prepared. Results may vary depending on growing conditions, plant variety, and preparation methods. This research cannot tell us how much of these plants someone would need to eat to get meaningful iron, or whether eating them regularly would actually improve iron levels in people.

The Bottom Line

Based on this research, avocado leaves, roselle calyces, and dried roselle leaves appear to be safer choices than fresh roselle leaves if considering these plants as iron sources. However, these are not traditional foods in most diets. If you’re interested in plant-based iron, focus on well-established sources like beans, lentils, spinach, and fortified grains. If you have iron deficiency or are considering using plant leaves as supplements, consult your doctor first. Confidence level: Moderate—this is laboratory research that needs human studies to confirm real-world benefits.

This research may interest people exploring plant-based nutrition, those in cultures where these plants are traditionally consumed, or people researching alternative iron sources. It’s less relevant for people with adequate iron intake from standard foods. People with iron deficiency should not rely on these plant leaves without medical guidance. Those with kidney disease or certain health conditions should avoid high-oxalate foods.

If these plants were used as iron sources, it would take weeks to months of regular consumption to potentially affect iron levels, similar to other dietary changes. Iron deficiency correction typically requires consistent dietary changes or supplementation over several months.

Want to Apply This Research?

  • If using avocado or roselle products, track weekly consumption amounts and monitor energy levels, as iron deficiency symptoms (fatigue, weakness) improve gradually. Record any digestive changes or side effects.
  • Start by incorporating one serving of iron-rich plant foods daily (beans, lentils, or fortified grains) rather than relying on less common plant leaves. If interested in roselle or avocado leaves, consult a healthcare provider first and use only small amounts as part of a varied diet.
  • Track iron-rich food intake weekly and monitor symptoms of iron status (energy levels, exercise tolerance) monthly. If using these plants regularly, get blood iron levels checked every 3-6 months through your healthcare provider to ensure effectiveness.

This research is laboratory analysis only and does not prove that eating these plants will improve iron levels in people. Iron deficiency is a medical condition requiring professional diagnosis and treatment. Do not use plant leaves as a substitute for prescribed iron supplements or medical treatment without consulting your healthcare provider. Individual iron needs vary based on age, sex, health status, and other factors. Always consult with a doctor or registered dietitian before making significant dietary changes, especially if you have iron deficiency, kidney disease, or take medications that interact with iron.