Chemical iron supplements can have significant side effects by promoting oxidative damage to the body, leading to significant health problems such as inflammation, liver disease and cancer (especially in chronic users) (1).
Vegetable juices are an important non-invasive and economical way to improve blood parameters, without the presentation of special side effects such as the above.

1. Juice based on raw beetroot.
Beetroot juice helps to improve hemoglobin levels in the blood (2). Specifically, in an experimental study involving 60 adolescent girls, it was found that supplementing with 100ml of beetroot juice daily for 20 days led to a significant improvement in hemoglobin levels (from 10.04 to 12.67 on average) compared to adolescent girls who did not consume the juice in the experiment (control group) and showed low hemoglobin levels (10.14 on average) (2).
Also, in a similar study, it was found that administering 200ml of beetroot juice to female soccer players for 6 weeks and 2 hours before training led to significant increases in hematocrit, hemoglobin, blood iron with a decrease in TIBC (Total Binding Capacity), compared to individuals (control group) who did not consume this juice (3).

2. Wheatgrass Juice (high in chlorophyll).
Natural wheatgrass juice has been studied for its possible effects on the management of anemia.
It is particularly rich in natural chlorophyll (structure similar to hemoglobin), folic acid and iron (4).
Studies have shown that its consumption is associated with improved hemoglobin levels (4,6,7), as well as with possibly better management of Mediterranean anemia in children (5,6).

- Other green vegetables and herbs rich in chlorophyll and iron that may have a similar effect to wheatgrass are parsley, spinach, spirulina, beetroot, and other green vegetables.

- You can make nutritious juices using several of the above vegetables with the addition of lemon or green apple to manage their intense flavor.-

Sources:
1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC340385/
2. http://iosrjournals.org/…/papers/vol2-issue1/C0210913.pdf
3. http://jkums.com/en/articles/82300.html
4. https://www.austinpublishinggroup.com/…/ijns-v2-id1014.php
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5947926/
6. http://www.chemijournal.com/…/vol2issue4/PartA/2-3-9.1.pdf
7. http://www.iosrjournals.org/…/Version-4/I1102045764.pdf