Are vegetarians at risk of iron deficiency?
Vegetarian and vegan diets generally contain just as much or more iron than mixed diets containing meat. The 2003 UK National Diet and Nutrition Survey showed that a vegetarian diet was not associated with lower-than-average total iron intake and that there was little association between indicators of iron status and dietary iron intake. Compared with meat-eaters, vegetarians may often have lower serum ferritin levels (although still within the normal range), even when their iron intakes are adequate, but the physiological impact of reduced ferritin levels in vegetarians is unknown at this time. Vegetarians may reduce their risk of low iron levels by eating foods rich in enhancers, such as vitamin C and organic acids.
In Western countries like Australia, where they enjoy a varied food supply, vegetarians are no more likely to suffer from iron deficiency anaemia than non-vegetarians. Low iron stores, without iron deficiency anaemia, have not been shown to adversely affect function. Iron deficiency clearly impairs function only when haemoglobin concentrations are measurably decreased, but this has not been shown across all studies. In the large European Prospective Investigation into Cancer and Nutrition (EPIC)-Oxford study of 43 000 women, vegetarians and non-vegetarians had similar iron intakes and haemoglobin concentrations. Many studies in Western societies suggest there is little difference, if any, in iron status (measured by haemoglobin levels, haematocrit, total iron-binding capacity, transferrin saturation and serum iron levels) between vegetarians and non-vegetarians, but a number of studies suggest that vegetarians are at greater risk of having low iron stores (as reflected by serum ferritin).
There are three levels of iron deficiency commonly used to evaluate iron status:
Depleted iron stores
Depleted iron stores are indicated by a serum ferritin level of < 12–15 µg/L,† but no apparent limitation in iron supply. An increased total iron binding capacity (TIBC) indicates depletion of iron stores, but is a less precise measure than ferritin level.
- Serum ferritin concentration < 12 µg/L
- TIBC > 400 µg/dL
Early functional iron deficiency
In early functional iron deficiency, iron supply to the bone marrow and other tissues is suboptimal, but there is no decrease in haemoglobin level and therefore no anaemia.
- Transferrin saturation < 16%
Iron deficiency anaemia
In iron deficiency anaemia, there is a measurable deficit in erythrocytes, the most accessible functional compartment.
- Haemoglobin concentration < 135 g/L (male); < 115 g/L (female)
- Mean cell volume < 80 fL
* Adapted from United States Institute of Medicine Panel on Micronutrients. † < 12 µg/L in US; < 15 µg/L in Australia.
Of course these are only a few, you may read about the healthy values in that of Kale, here.
To read more about this interesting and controversial topic, see the original Medical Journal Australia report.