Vegans and Iron – What you need to know
You may think getting enough iron is all about red meat and spinach, but you’d be wrong. Here is the Tasty Vegan’s guide to optimising iron intake on a plant-based diet. Vegans and iron are not mutually exclusive, despite the stereotype.
Vegans and Iron
Omnivores are rarely asked about their iron levels, which is odd, considering that research suggests omnivores have similar levels to most vegetarians and vegans. If the best dietary iron sources are animal-derived products, why would iron levels be generally the same between omnis and veg*ns? One explanation may be that those who consciously choose a non-standard diet tend to be more aware of potential dietary pitfalls. Think Protein Panic and fear over B12!
The iron in animal flesh is, for the most part, bound to a protein molecule called haem/heme. Around 65% of iron in meat is in the form of haem iron and is pretty easily absorbed. It makes sense that meat is rich in iron. After all, our own animal flesh and blood is where our iron is put to use, carrying oxygen around the body.
The rest of the iron in meat, and in plants, is a little different and is often not as well absorbed. Non-haem iron requires a protein called transferrin to be present in the digestive tract in order to cross into the bloodstream. This non-haem iron also has to be released first from other components of food through the action of hydrochloric acid (stomach acid) and pepsin (a digestive enzyme). People with low levels of stomach acid or digestive enzymes are more susceptible, therefore, to iron deficiency when eating a predominantly plant-based diet.
Recommended Daily Iron Intakes
The recommended dietary allowances (RDAs) for iron for adults aged 19-50 are 8 mg for men and 18 mg for women. This is the minimum to stave off deficiency, not the optimal amount for excellent health. Iron is toxic at high levels, however, and iron supplements should always be kept out of reach of children. A bottle of iron pills contains enough of the mineral to kill a child.
Fortunately, supplements are not always necessary to boost iron levels for vegans (and omnis). There are plenty of good vegan-friendly sources of iron. Eating a varied and balanced diet and employing a few tips and tricks to boost iron absorption can help us keep our circulating iron and iron stores tickety-boo.
Things that Inhibit Iron Absorption
One of the most useful things to know about absorbing plant-based iron is wrapped up in the delightful little acronym TOPHYPHOS:
These four things inhibit the absorption of non-haem iron. This means, for example, that you’ll likely absorb more iron from kale (a medium-range source of iron) than you will from spinach (a rich source of iron). Spinach contains a lot of oxalic acid (an oxalate), while kale is low in oxalates.
It’s not just what you eat that is important for iron absorption. For instance, if you’re trying to boost your iron levels, try to eat iron-rich foods (or take iron supplements) separately to the following foods:
- Tannins – tea, berries, grapes, persimmon, chocolate, sorghum, corn
- Oxalates – spinach, rhubarb, beets and beet greens, Swiss chard, almonds, sweet potatoes, peanuts
- Phytates – unleavened bread and unrefined cereals and legumes, refined cereals, starchy roots and tubers
- Phosphates – fizzy, carbonated drinks, bread, bran, muesli and raw oats, brown rice, soy flour, white self-raising flour, cashews and almonds.
Tannins and Phosphates
Although they inhibit non-haem iron absorption, tannins are not all bad. Proanthocyanidins are a type of tannin and are potent antioxidants. Tannins have also demonstrated anthelmintic properties, i.e. they destroy parasites. So, rather than totally cutting out tannin-rich foods, it’s just smart to avoid having those foods in your belly when you’re deliberately eating foods to boost your iron levels.
Phosphates are also beneficial to health. In fact, phosphorus is essential for healthy bones!
Oxalates and Phytates
Oxalates not only inhibit iron absorption, they also bind to calcium and can increase the risk of kidney stones. However, a plant-based diet actually seems to reduce the risk of kidney stones, according to a study by Harvard School of Public Health. And, it’s preferable to have a diet high in fruits and vegetables, rather than eschewing such foods because of a disproportional fear of oxalates.
Phytates are generally found in unrefined cereals and legumes. These compounds can have a dramatic effect on the absorption of iron, zinc, calcium, and manganese. Iron absorption may be as low as 2-3% from whole-grain porridge and legumes, where the phytic acid content is around 1 g/100 g (Hurrel, 2003). This is true even for people who are iron-deficient (iron deficiency typically leads to increased iron uptake).
Decreasing the phytic acid content of foods by 90% can increase iron uptake two-fold. More modest decreases don’t seem to make a lot of difference, however (Hurrell, 2003). As such, avoiding eating foods high in phytates alongside iron-rich foods appears to be the best approach in general.
Calcium supplements also inhibit iron absorption, as do coffee and green tea.
Next, let’s take a look at ways to boost iron absorption.Want carbon-neutral webhosting with great customer service? Try DreamHost and use code 'Vegans' for a third off!