June 03rd, 2021

Iron In A Vegan Diet

Obtaining optimal iron from a plant based diet is a common concern.  Iron deficiency is the most common nutritional deficiency in the world.  In Western countries, energy restricted diets tend to be the cause.  In developing countries, food scarcity is to blame. 
Insufficient iron intake is only one factor contributing to iron deficiency anaemia.  Other factors include:

• -impaired iron absorption, such as inflammatory bowel disease (Crohn’s or coeliac disease),
• - internal bleeding from the gastrointestinal tract in conditions such as ulcerative colitis, diverticulitis and peptic ulcers,  
• - zinc supplementation impairing iron absorption, and
• - menstruation -the most likely cause of iron deficient anaemia.

Plant based foods contain natural iron absorption inhibitors (discussed below), thus the recommended iron intake for vegans is 1.8 times greater than standard recommendations.  For women aged 19-50, the recommended  iron intake is 18 mg a day, so for vegan women it is 32.4 mg a day (1.8 x 18).
This increased requirement does not consider the fact that iron absorption from non-heme iron, plant based iron, increases at times of increased need, such as pregnancy or poor intake.  We will not however discuss this further here.

Types of Iron
Ingested iron is found in two forms, heme iron, found in animal foods, and non-heme iron, in plant foods.  Non-heme iron is less readily absorbed, and can lead to lowered iron stores or lowered serum ferritin.  This is actually shown to be protective against non communicable diseases, which account for 70% of deaths worldwide and are driven by unhealthy diets, smoking, lack of activity and excessive alcohol.
Absorption of non-heme iron adjusts with our our needs.  In contrast, heme iron is readily absorbed regardless of need, increasing risk of cardiovascular disease and certain cancers. There is no association with non-heme iron and these health risks.

​Increasing non-heme iron absorption
Phytic acid is a phytonutrient that binds minerals, including non-heme iron, lowering absorption, and is found in grains, legumes, nuts and seeds.  Phytic acid is not all that bad however as it can lower blood glucose and lipid levels, has anti-cancer and antioxidant properties and can reduce arterial calcification. 
50 mg of vitamin C can enhance non-heme iron absorption sixfold in those with low iron stores to offset phytic acid.  Thats about 30g of red capsicum or half a kiwi fruit or one quarter cup of orange juice.
Allium foods can also diminish the effects of phytic acid by adding onion and/or garlic, sulfur compound-rich allium foods, to grains and legumes while cooking.  Soaking, or activating, nuts, seeds and oats also reduces phytic acid. 
As with absorption of all nutrients, optimal digestion is key. This begins with fully chewing your food and eating in a relaxed state to stimulate digestive enzymes.  Gastric acid is required for iron, and B12, absorption.  Zinc deficiency can impair gastric acid production as can the use of proton pump inhibitors.

Diet Plan
See below for a one day plant based diet plan providing 40.2mg of iron, exceeding that required by women aged 19 to 50.

Breakfast - Quinoa and chia raspberry pudding
2 tbsp chia seeds
0.5 cup cooked quinoa
0.5 cup raspberries
200ml soy milk
Snack
20 g cashews
0.25 Cup dried apricots
Lunch - Spinach with lentils.7
5 C lentils cooked
2 C spinach
1 tbsp dried thyme
salt, olive oil, lemon juice and other flavours/vegetables as desired
Dinner - stir fried tofu
1 C cubed tofu
1 tbsp dried thyme
serve with veggies of choice (mushrooms, corn, cabbage, etc) and flavouring of choice (soy sauce, tahini, curry powder, etc.)

References

• Iron and vegetarian diets, 2013 doi: 10.5694/mja11.11494 

 

• Iron Status of Vegetarian Adults: A Review of Literature, 2016, doi.org/10.1177/1559827616682933

 

• The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis, 2016, doi.org/10.1080/10408398.2016.1259210

 

• WHO, n.d. https://www.who.int/health-topics/noncommunicable-diseases#tab=tab_1

 

• Dietary intake of heme iron and risk of cardiovascular disease: A dose–response meta-analysis of prospective cohort studies, 2014, doi.org/10.1016/j.numecd.2014.09.002

 

• Heme iron from meat and risk of adenocarcinoma of the esophagus and stomach, 2012,  doi: 10.1097/CEJ.0b013e32834c9b6c  

 

• A Review of Nutrients and Compounds, Which Promote or Inhibit Intestinal Iron Absorption: Making a Platform for Dietary Measures That Can Reduce Iron Uptake in Patients with Genetic Haemochromatosis, 2020, doi.org/10.1155/2020/7373498

 

• Higher Bioaccessibility of Iron and Zinc from Food Grains in the Presence of Garlic and Onion, 2010, DOI:10.1021/jf100716t

 

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