Why You Should Take Iron With Vitamin C for Better Absorption

Taking iron with vitamin C helps your body absorb more of it. Vitamin C is the strongest known enhancer of non-heme iron, the kind in plant foods and most supplements. It changes ferric iron into the more soluble ferrous form and stops insoluble iron compounds from forming in the small intestine, so more iron gets into your body.

That matters because iron is needed for hemoglobin, energy production, brain function and immunity, and your body isn't very good at absorbing it. Here's how the pairing works and how to time your iron to get the most out of it.

How iron and vitamin C work together

Your body uses iron to make hemoglobin, the protein in red blood cells that carries oxygen from your lungs to the rest of your body. The problem is absorption. Heme iron, from animal foods, is fairly easy to absorb. Non-heme iron, from plants and fortified foods, is much harder.

Vitamin C (ascorbic acid) acts as a reducing agent. It converts non-heme iron into a form the cells lining your gut can carry across their membranes. Our article on the role of vitamin C in iron absorption goes into the chemistry.

This matters on a large scale. The World Health Organization (2021) estimates that iron deficiency affects more than 2 billion people worldwide, which makes it the most common nutritional disorder. Getting enough iron isn't only about how much you take in but how much your body can use.

Heme vs non-heme iron

The difference between heme and non-heme iron explains why vitamin C helps. Heme iron, which comes from hemoglobin and myoglobin in animal tissue, is typically absorbed at 15% to 35%. Non-heme iron absorption can be as low as 2% to 20%, depending on what else is in your meal.

When you take iron with vitamin C, the ascorbic acid binds the iron into a complex that stays soluble even at the higher pH of the small intestine. That keeps the iron from binding to phytates or polyphenols, which would otherwise carry it out of your body unabsorbed.

Why it matters for women

Women of childbearing age are at particularly high risk of low iron because of monthly blood loss. Low stores can affect how you feel before any anemia shows up. In a 2012 randomized controlled trial in CMAJ, Vaucher and colleagues found that iron significantly reduced fatigue in women who had low ferritin but were not anemic.

Symptoms like brain fog, cold hands and brittle nails can appear well before a diagnosis of anemia. In a 1996 study in The Lancet, Bruner and colleagues found that iron deficiency impairs cognitive function and attention even before hemoglobin drops below the anemia threshold. Our guide to iron deficiency in women covers the signs in detail.

What blocks iron absorption

Some foods and drinks work against vitamin C. Our article on common iron absorption inhibitors has the full list. The main ones:

• Tannins and polyphenols: in tea and coffee, these can cut iron absorption by 60 to 90 percent if you drink them with or right after a meal.
• Phytates: in whole grains, legumes and nuts, these bind iron and block its uptake.
• Calcium: high doses from dairy or supplements can compete with iron for absorption.
• Oxalates: in spinach and beet greens, these also reduce how much non-heme iron you absorb.

Take your iron at least one hour before or two hours after these.

Gummies, pills and powders

Gummy vitamins with iron are easy to remember and pleasant to take, but they have drawbacks. Iron's metallic taste is hard to hide in a gummy, and many gummies don't include enough vitamin C or B12 to help much if you're significantly deficient.

Powders and stick packs can deliver iron with vitamin C in one dose, and some formats use gentler forms of iron, such as iron bisglycinate or micronized iron, that are less likely to cause constipation or nausea. Our guide to finding the best iron supplement for women compares the options.

Iron and vitamin D

Researchers are also looking at iron and vitamin D. Some studies suggest low vitamin D may be linked to higher levels of hepcidin, the hormone that regulates iron balance. High hepcidin suppresses iron absorption. So adequate vitamin D may indirectly help you maintain iron levels, although it doesn't enhance absorption the way vitamin C does.

How to take iron for the best absorption

Iron is usually recommended on an empty stomach, away from foods that block it. If that upsets your stomach, taking it with a little vitamin C-rich fruit, such as an orange or some strawberries, may be easier to tolerate while still helping absorption.

A supplement that already contains vitamin C makes this simpler, because the vitamin C arrives in your gut at the same moment as the iron, which is when it helps most.

Where Go Wise Iron fits

We built Go Wise Iron around dose. Each stick has 9 mg of iron (as ferrous fumarate), which is 50% of the Daily Value, with 45 mg of vitamin C to help absorption, plus vitamin B6, vitamin B12 and folic acid. A standard ferrous sulfate tablet delivers about 65 mg of iron. Stomach upset and constipation tend to rise with the amount of iron that reaches your gut, and your body absorbs a larger share of a small dose than of a large one, partly because big doses raise hepcidin, the hormone that holds back iron absorption. Every batch is third-party tested by Eurofins for heavy metals and microbial contamination, and it is made in a GMP-certified facility.

It's a powder stick you pour onto your tongue, with no water needed and no metallic aftertaste. It's vegan, gluten-free and made in the USA. At 9 mg a day it's designed for steady, long-term support. If you've been diagnosed with iron deficiency anemia, your doctor may prescribe a higher treatment dose, so ask how a daily stick fits alongside it.

References

• Vaucher et al. CMAJ. 2012.
• Bruner et al. The Lancet. 1996.

This article is for general information and isn't medical advice. Talk to your healthcare provider before starting a supplement, especially if you are pregnant, nursing or taking other medication.