Spinach is sometimes considered a good source of iron, especially when paired with ascorbic acid (vitamin C) as described in this answer.

If I am consuming spinach by blending it up in a smoothie, how much orange juice (or whole oranges, lemons, or limes) need to be added or consumed to provide enough vitamin C to help with iron absorption? Does the amount of vitamin C required go up when consuming larger amounts of spinach?

Also, does the freshness of orange juice make a difference to the amount needed?

1 Answer 1


Consume equal parts spinach and orange/lemon juice for best absorption of iron. It’s okay to drink more orange or lemon juice than that, but it might be more costly.

The presence of vitamin C is most important when eating foods that also contain inhibitors of iron absorption. Orange juice and spinach are a great combination.

The promotion of iron absorption in the presence of AA is more pronounced in meals containing inhibitors of iron absorption.

A ratio of 7 mg ascorbic acid (vitamin C) to 1 mg iron is sufficient for foods with medium levels of inhibitors, though a higher ratio of 14:1 may promote absorption when high levels of inhibitors are present.

Meals containing low to medium levels of inhibitors require the addition of AA at a molar ratio of 2:1 (e.g., 20 mg AA: 3 mg iron). To promote absorption in the presence of high levels of inhibitors, AA needs to be added at a molar ratio in excess of 4:1, which may be impractical.

A single serving of spinach (30 grams, or approx 30 baby leaves) contains 0.81 mg iron. To support absorption, the serving should be paired with 5.7-11.4 mg vitamin C. Orange juice is very rich in vitamin C, and 11.4 mg vitamin C is provided by just 25 ml of orange juice. Just one tenth of a cup of orange juice is sufficient to pair with one serving of spinach.

Here's a quick summary. Roughly speaking, equal parts spinach and citrus (orange or lemon juice) enable good digestion of the non-heme iron in spinach.

                               Orange juice (ml)  Lemon juice (ml)
One serving spinach (30 g)                    25                30
Five servings spinach (150 g)                125               150

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.