A Frequently Asked Question Is:
“In a vegan/vegetarian diet, where do I obtain adequate iron?” or
“Will I become iron deficient if I do not eat red meat and other animal products?”
Why Do We Need Iron?
Iron, a mineral, is essential to all body cells. Iron functions primarily as a carrier of oxygen in the body, both as a part of haemoglobin in the blood, and as a part of myoglobin in the muscles.
90 percent of the iron in the body is conserved and reused every day; the rest is excreted. Men store more iron than women.
In order to maintain iron balance in the body, dietary iron must supply enough iron to meet the 10 percent gap that our body has excreted, or else deficiency will result.
An appropriately planned, well-balanced vegetarian diet is compatible with an adequate iron status. This is in contrast to the claims of the meat industry.
About two thirds, 67 percent, of body iron is present in haemoglobin and myoglobin. Haemoglobin, which is present in the red blood cells, is essential for transferring oxygen from the lungs, via the blood, to the tissues. Myoglobin is present in the muscle cells and accepts, stores, transports and releases oxygen in the muscles.
Some 6 percent of body iron is used as a component of certain proteins – it forms part of the cytochromes, which are essential for respiration and energy metabolism. Iron is also a component of certain enzymes involved in the synthesis of collagen and various neurotransmitters, and it is needed for proper immune function and cognitive development.
About 25 percent of the iron in the body is stored as ferritin, which is found in cells and circulates in the blood. The average adult male has about 1000mg of stored iron, whereas women on average have only about 300mg. When iron intake is chronically low, stores can eventually become depleted, decreasing haemoglobin levels and resulting in iron-deficiency anaemia.
Iron deficiency anaemia can also be caused by heavy blood loss through injury, heavy menses, ulcers, haemorrhoids, colorectal cancer and drug ingestion such as acetylsalicylic acid (aspirin). It can range from acute loss as in trauma to slow ‘occult’ loss as with chronic aspirin ingestion.
Symptoms of Iron Deficiency
There is a variety of possible symptoms of iron deficiency (many the direct result of anaemia with low haemoglobin and reduced red cell count), including:
· lack of energy
· fatigue and feeling of weakness
· pale skin
· light headedness
· pallor of the lining of the eyes (inside the lower eyelid), inside the mouth and the nail beds
· rapid and strong heat beat
· postural hypotension (a drop in blood pressure with position change from sitting to standing)
· tongue may become sore, smooth and reddened
· decrease in appetite
· shortness of breath on exertion
· brittle and dry hair
· reduced immunity and increased vulnerability to infection
Because these typical symptoms of iron deficiency may have many causes apart from anaemia, diagnosis by a blood test (full blood count and ferritin levels) is needed to confirm the presence of iron deficiency anaemia.
Normal levels (ranges) of haemoglobin are:
· Men - 35 to 165 gm/litre
· Women - 121 to 151 gm/litre
· Children - 110 to 160 gm/litre
If the concentration is below normal, this is called anaemia.
Ferritin is a protein that stores iron. Serum ferritin is the most useful test in the diagnosis of iron deficiency. In healthy people, it accurately reflects iron stores: a level below normal is diagnostic of iron deficiency.
· A ferritin level greater than 20ng/ml represents adequate iron stores
· A ferritin level in the 12-20 ng/ml range indicates that the iron stock pile is minimal
· A ferritin reading below 12ng/ml shows that iron stores in the bone marrow (where the red cells are formed with their haemoglobin) have become completely depleted.
Types of Dietary Iron
Iron in food occurs in two forms:
· Haem iron. This is found only in meat, seafood and poultry. Approximately 40 percent of the iron in meat products is haem iron.
· Non-haem iron. 60 percent of the iron in meat, and all the iron in plant foods (primarily in fruits, vegetables, dried beans, nuts and grains) is non-haem iron.
In general, iron is not readily absorbed by the body. The body uses several mechanisms to regulate iron absorption. Controlling absorption is important because the body cannot easily excrete excess iron once it is absorbed. The extent of iron absorption depends on a variety of factors, the most important of which is the size of the current iron stores (ferritin) in the body. If these are depleted, there is a marked increase in the capacity of the body to absorb iron to correct the depleted levels. Conversely, if the level of the iron stores is high, the absorption of dietary iron is reduced in order to try to prevent iron overload from occurring.
The absorption of the two types of iron differs:
· About 20 percent of haem iron is absorbed.
· About 2-20 percent of non-haem iron is absorbed.
· Non-haem iron is much more sensitive to the enhancers and inhibitors of iron absorption than is haem iron.
Enhancers of Iron Absorption
· Low body stores.
· Vitamin C. Vitamin C (ascorbic acid) significantly enhances the absorption of non-haem iron. For this to occur, the vitamin C source and the iron (non-haem) must be consumed at the same meal.
· A haem food, and a non-haem food, when eaten together. This helps in the absorption of the iron from the non-haem source.
· Fruits and vegetables, apart from vitamin C (ascorbic acid), also contain small amounts of other organic acids, for example, citric and malic acids, which can enhance non-haem absorption.
· Adequate hydrochloric acid in the stomach.
Inhibitors of Iron Absorption
· Full body stores.
· Reduced hydrochloric acid (hypochlorhydria) in the stomach.
· Large amounts of tea consumed with the meal. This is due to the tannins: these polyphenols bind the iron, reducing absorption by up to 50 percent. Tea is not a problem unless consumed with the meal.
· Excessive consumption of high fibre foods such as whole grains, legumes or bran supplements. This is due to the presence of phytates, which inhibit absorption.
· Oxalic acid, for example as found in spinach.
· Calcium and phosphorous, especially in cows’ milk and milk products. If you take a calcium supplement, do not take it at the same time as an iron supplement.
Studies have shown that when iron intake from plant foods is relatively high, and a variety of foods is consumed, the inhibitors and enhancers of iron absorption can offset each other and iron balance is not adversely affected.
Recommended Dietary Allowance (RDA) for Iron
· Non-vegetarian men - 8mg/day
· Non-vegetarian pre-menopausal women - 18mg/day
· Non-vegetarian post-menopausal women - 8mg/day
· Non-vegetarian children (4-8years) - 10mg/day
· Vegetarian men - 14mg/day
· Vegetarian pre-menopausal women - 33mg/day
· Vegetarian post-menopausal women - 14mg/day
For adults, the upper level of intake should not exceed 45mg/day. These figures are a guide only, and have been sourced from various publications, mainly from USA.
Dietary Sources of Iron
The best way to get an adequate amount of iron is to eat a variety of foods that contain iron. Healthy individuals who eat a balance diet rarely need iron supplements.
When cooking, in order to retain the iron:
· cook foods in a minimal amount of water
· cook foods for the shortest possible time.
However, remember that raw is better (see my April 2007 newsletter ‘Cooked Food is Poison-Why Raw is Better’).
Although I believe a plant-based, low-fat diet is the ideal, the following sources listed include both haem and non-haem sources.
Iron Rich Foods
a) Haem Sources:
· Liver: chicken, calves, beef (up to 12mg per 100gm)
· Lean red meat: pork, beef, lamb (1mg-4mg per 100gm)
· Seafood: oysters, mussels, tuna, salmon, prawns, fish (up to 4mg per 100gm). Raw oysters have 4mg per 100gm
· Chicken and turkey (up to 2mg per 100gm).
b) Non-haem Sources:
· Nuts and seeds, especially almonds, pine nuts and pumpkin seeds (1.5mg-4.0mg per 2 tablespoons)
· Beans, including kidney, lima, navy and black (1.5mg-4.0mg per ½ cup cooked)
· Lentils (up to 6.5mg per cup cooked)
· Spinach (4.5mg-7.0mg per ½ cup cooked)
· Soy beans (4.5mg – 7.0mg per ½ cup cooked)
· Vegetables including broccoli, asparagus, parsley, peas, watercress, brussel sprouts, kale (up to 2.5mg per ½ cup)
· Dried fruits such as raisins, prunes, dates and apricots (up to 4mg per ½ cup)
· Molasses (1.0mg-2.5mg per 1 tablespoon)
· Grains: breads, cereals and other grain products. Most of these are ‘enriched’ or ‘fortified’ (up to 7mg per 100gm). Where possible, only eat wholegrain (ie, unrefined) grain products.
The above amounts of iron (in mg) have been extracted from various published sources. They are given as guidelines; clearly, the actual amount depends upon variable factors such as the nature of the soil in which the fruits or vegetables were grown and the type of the feed of the animals etc. One published paper showed a big difference in iron content of vegetables, eg spinach, when grown organically – there was up to a 10 fold difference when compared to those grown using conventional fertilisation etc.
Enriched or Fortified Foods
Pasta, white rice, and most breads and other wheat products made from refined flours, are enriched with iron, because iron is one of the nutrients lost in processing. Other nutrients that are added to refined flours and pasta include thiamine, niacin and riboflavin (B vitamins). Enriched products, and products made from enriched flour, are labelled as such, and should show the amount of iron added.
In iron deficiency, an oral supplement of an iron salt such as ferrous sulphate or ferrous glutamate can be prescribed. These are inorganic salts and are poorly absorbed and often associated with side effects such as constipation. An organic iron preparation, such as Floradix, is better absorbed and better tolerated.
Excessive iron intake should be avoided. Iron is a pro-oxidant; it promotes the oxidative damage that is linked to many chronic diseases. Excess iron stores (and intakes) have been linked to increased risk of heart disease and certain forms of cancer, particularly colorectal cancer.
Toxicity can occur if too much iron is absorbed. The major cause of this is haemochromatosis, a hereditary condition. It is rare and is caused by a distinct gene that favours excessive iron absorption if it is readily available in the diet. Saturation of iron in the tissues can lead to tissue damage, specifically damage to the liver and heart.
At the beginning of this newsletter, the questions as set out essentially asked if there is adequate iron in a vegetarian/vegan diet.
The incidence of iron-deficiency anaemia is not significantly different between vegetarians and non-vegetarians. However, vegetarians should not be complacent about iron, and should eat a diet that emphasises iron-rich foods, and takes into consideration the enhancers and inhibitors of iron absorption.
Adequate dietary intake of iron is an essential for everyone.
If you have concerns about your iron level, a simple blood test for red cell characteristics (haemoglobin) and iron stores (ferritin) will give an accurate indication of your current iron status.
If there is evidence of iron deficiency or of low iron stores, your health care provider should be consulted. It is important to identify, and treat where appropriate, other causes of iron deficiency that are not nutritional.
* Copyright 2008: The Huntly Centre.
Disclaimer: All material on the huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.
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