Iron Absorption

Up to 22% of the iron in meat is absorbed, while only 1-8% is
absorbed from eggs and plant foods. If the body stores fall, the rate
of iron absorption rises. About 40% of the iron in animal foods is in
a form called haem iron, while the remainder, and all the iron in
plant foods, is in the less well absorbed non-haem form. Iron
absorption can also be reduced by tannins (e.g. in tea) and phytates
(found in nuts, grain and seeds). At this point one tends to wonder
whether the rumours of vegans suffering from anaemia have substance,
however, this isn't the whole story and the reader will be heartened
to learn that research has shown that iron deficiency in vegans is no
more common than in the rest of the population.

The absorption of iron from plant foods is improved by the presence
in a meal of vitamin C (ascorbic acid), other organic acids such as
malic acid (e.g. in pumpkins, plums and apples) and citric acid (in
citrus fruits). Laboratory research in which experimental meals were
given to 299 volunteers has shown that the inclusion of foods (such
as fresh salad, orange juice or cauliflower) providing 70-105mg of
vitamin C in each meal increased the absorption of iron. A
particularly pronounced effect was seen when 4.5oz cauliflower
containing 60mg of vitamin C was added to vegetarian meals, causing
more than three-fold increase in iron absorption. [1]

Earlier studies have shown that, when iron intake from plant foods is
relatively high (14-26mg/day), even large amounts of phytate do not
adversely affect iron balance. [2]

There has been some concern that fibre in food can also inhibit the
absorption of iron. However a study has shown that the iron balance
was more favourable when fibre intake was 59g a day, than on a low-
fibre regime of only 9g.

Iron, Vegans and the General Population
Iron deficiency is believed to be fairly common in the general
population and a 1985 survey of young British omnivore women showed
that, on average, they were consuming only just over half the current
recommended intake. The Dietary and Nutritional Survey of British
Adults revealed that one third of all women had low iron stores.
Symptons of iron deficiency anaemia include tiredness and
breathlessness especially on physical exertion, giddiness,
palpitations, headache and poor concentration.

Studies of British vegans have reported an average intake of
approximately double the recommended Reference Nutrient Intakes. At
this level of iron consumption, any possible inhibitory effects of
fibre and phytate on absorption are unlikely to be important. As
vegan diets contain about three to four times the British and US
recommendations for vitamin C, absorption of iron is enhanced.

Conclusions
Vegans have a high dietary iron intake and although iron from plant
sources is less well absorbed than that from meat, high levels of
vitamin C in the diet enhances iron absorption. Studies show that the
iron status of vegans is usually normal, and iron deficiency is no
more common than in the general population.

Further Details
For more details on vegan nutrition see Plant Based Nutrition and
Health by Stephen Walsh. This book is the most comprehensive survey
of scientific research on vegan diets. It is ideal for vegans, would-
be vegans and health care professionals