Food absorption rates

The recommended daily allowance (RDA) of iron is 14mg however this takes into account that the average person is unable to absorb most of the iron from food sources. An adult woman needs to absorb between 1.5-2mg of iron per day. This increases to 3-6mg during the last trimester of pregnancy.

Many substances in iron-rich foods inhibit the absorption of iron that is why it's very difficult to get your RDA of iron from your diet. This is particularly true for women, pregnant women, children, teenagers and endurance athletes who are well-known to have an increased need for iron.

On average only 5-20%¹ of iron from food sources is absorbed as most foods contain (or are consumed with) substances which inhibit the absorption of iron. Well known iron inhibitors include tannins found in tea, coffee and red wine or bran found in wheat, oats, maize and cereals. 

The below table summarises foods rich in iron with their respective iron content per 100g and per recommended serving.

The nutrient density specifies the significance of iron as a proportion of the food. Foods with higher nutrient densities provide an increased bioavailability of iron.

Absorption of iron is generally increased if the consumption of tea and coffee is avoided. Vitamin C (e.g. a glass of orange juice) is considered to help the absorption of iron.

It is important to note that individuals will absorb their nutrients at different rates depending on their state of health and digestive system. 

Spatone has been scientifically shown to have a bioavailability of 40% (that is the iron available for absorption) compared to  20%¹ from food sources 10%² from iron tablets .

1 Webster-Gandy J, Madden A, Holdsworth M Ed's (2006) Oxford Handbook of Nutrition and Dietetics. Oxford University Press, Oxford.

2  D. McKenna (Royal Victoria Hospital) et al. 'a randomised trial investigating and iron-rich natural mineral water as a prophylaxis against iron deficiency in pregnancy' in Clinical and Laboratory Haematology, 2003, 25 99-103

Copy and data supplied by Joanna Lyall,
Nutritional Therapist.

The iron content quoted in the above table is based on data used by the George Mateljan Foundation and the World Healthiest Foods (whfoods.org).

The nutrient breakdown data is supplied by ESHA (www.esha.com).  All figures have been referenced against the FSA McCance and Widdowsons Composition of foods data.