Iron Intake for vegetarians
Carrie Ho, HK BioTek Nutritionist
Feeling dizzy, languid, and weak after starting your vegetarian diet? It probably is due to insufficient iron intake.
There are plenty of haemoglobin found in blood which acts as a transporter to deliver oxygen to all body parts for respiration. We only feel energized when our brain receives sufficient oxygen and functions properly, in which iron plays aa vital role.
Iron in foods can be categorized into two groups:
1. Heme iron (from animal foods): usually found in meat, fish and poultry with an absorption rate of 15%-35%
2. Non-heme iron (from plants): usually found in vegetables, legumes and nuts with an absorption rate of less than 20%
Insufficient iron intake has been a growing issue in Hong Kong over the past few decades. It was not uncommon to see blood donors were rejected due to low level of haemoglobin. The case is even worse when it comes to vegetarians who can only rely on non-heme iron. However, to boost up iron intake is easier than expected and you only have to follow five major principles shown below!
1. Look for iron-rich foods
There are ample plant foods with high iron level apart from meat.
Sources: FoodData Central of The United States Department of Agriculture, Centre for Food Safety
Vegetarians are not recommended to absorb iron from a single food source because high iron content does not amount to high absorption rate. For example, soy sum and Chinese broccoli may be a better iron course for vegetarians given that spinach contains phytate which can inhibit iron absorption in body despite its high iron content. Additionally, we should not be oblivious of the serving size and kale is a case in point. Many prefer having uncooked kale (1.6mg iron in 100g) or keeping it as part of a salad, but the actual intake can be as few as 0.4mg when one bowl only accounts for 33g of raw kale.
2. Combine with high-Vitamin C foods
Vitamin C has been proven to enhance absorption of non-heme iron in human body. Including 1-2 servings of fruits after meal can surely help vegetarians absorb more iron, such as kiwifruits, bell peppers, berries, orange and so on.
3. Separate high-calcium and high-iron diets
Calcium and iron interfere each other’s absorption in intestines so vegetarians should avoid having high-calcium and high-iron foods simultaneously. For instance, you may alternative absorb these two nutrients by having a cup of calcium-fortified soymilk and almond butter toast for breakfast as well as eating fried spinach with black fungus at dinner.
4. Avoid tea and coffee with meals
Both tannins in tea and caffeine in coffee can dampen iron absorption. Therefore, vegetarians may keep their drinks 1 hour before or after meals.
5.Don’t forget vitamin B
Long-term fatigue and dizziness can also be the symptoms of vitamin B deficiency since the vitamin B family take part in red blood cell synthesis, metabolism and energy production, especially B6, folate (B9) and B12. B6 and folate can be found in grains or dark greens but B12 only comes from animals, which explains the common iron insufficiency in vegetarians. The only reliable vegan sources of B12 are yeasts, seaweeds and B12 supplements.
Iron is of paramount importance for health. Getting enough iron from foods is not impossible for vegetarian with the help of above five steps.
The daily recommended iron intake:
Adult men: 8mg
Adult women: 18mg
Pregnant women: 27mg
Adults aged 51 or above: 8mg
National Institutes of Health (2019). Iron, Fact Sheet for Health Professionals. US Department of Health & Human Services. Retrieved from https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
US. Department of Argriculture. (2019). FoodData Central. Retrieved from https://fdc.nal.usda.gov/index.html
Centre for Food Safety. (2017). Nutrient Information Inquiry. Retrieved from https://www.cfs.gov.hk/english/nutrient/index.php
Petre, A. (2017). 21 Vegetarian Foods That Are Loaded With Iron. Healthline. Retrieved from https://www.healthline.com/nutrition/iron-rich-plant-foods#section1
Hollingsworth, J. (2017, Feb 28). One in eight Hong Kong blood donors rejected due to low iron levels, Red Cross says. South China Morning Post. Retrieved from https://www.scmp.com/news/hong-kong/health-environment/article/2074817/one-eight-hong-kong-blood-donors-rejected-due-low