Plant-based Iron, Synergy & Wholefoods

edition 2This the unedited version of my iron article from Edition 2 of

The Australian Vegan Magazine

You can order your back copy here.


Iron is a mineral found in every living cell on earth, and in human nutrition, iron is considered a ‘trace’ mineral, because it’s only needed in very small amounts. We might not need much of it, and the human body has clever ways to make the most of those small amounts, but iron deficiency is a common world-wide deficiency. Interestingly enough, studies have shown that iron-deficiency anaemia is no more prevalent among vegans than non-vegans.

While iron performs uncountable roles in the human body, about two-thirds of the iron within us is found smack bang in the middle of our haemoglobin, a substance in red blood cells that contains a pigment called ‘haem’, linked with a protein called ‘globin’. The pigment gives blood its red colour. Haemoglobin can bind to and then release oxygen. Like a delivery truck, haemoglobin picks up oxygen from our lungs and delivers it to our cells in exchange for the waste product carbon dioxide, which it carries back to the lungs for expelling. If we don’t have enough haemoglobin (which cannot be made without iron), every cell in our body tires easily.

In centuries past, one of the home remedies for classic iron deficiency signs such as fainting and weakness, was to push iron nails into an apple and leave it overnight. The next day, the nails were removed and the apple was eaten. I’m not sure how effective a treatment this was, but it’s certainly been proven that cooking in cast iron pots can be a helpful method for improving iron status, especially if the food being cooked is acidic. For example, tomato sauce cooked in cast iron has up to 2.5 times the iron content it might have were it cooked in any other kind of pot. The plain elemental iron in cast iron pots is the least well absorbed form of iron, and only forms a very small portion of the iron we source from our diet.

The primary forms of iron in the diet of humans are heme iron and non-heme iron. Heme iron comes from haemoglobin, so it’s only found in animal flesh. Plants, on the other hand, only contain non-heme iron. Without iron, a plant can’t produce chlorophyll, a green-pigmented chemical which is remarkably similar in shape to our human haemoglobin. Both humans and plants alike, turn pale in the absence of iron! Chlorophyll pigments in plants are like mini-solar panels, absorbing light from the sun and using it to create energy by turning carbon dioxide and water into carbohydrates, with oxygen produced as a waste product. This clever means for turning sunlight into food is called photosynthesis, and is largely responsible for producing and maintaining the oxygen content of the Earth’s atmosphere, as well as suppling all of the organic compounds and most of the energy necessary for life on Earth.

Humans absorb heme iron at an average rate of 23%, while non-heme iron’s absorption average is only 10%. This doesn’t necessarily mean flesh is a better source of iron than plants. To begin with, heme iron only constitutes 40% of the iron in animal flesh; the other 60% is non-heme iron. When you do the math, this means the overall absorption of iron from animal flesh is 40% x 23% = 9.3% + 60% x 10% = 6% for a total of 15.3%, which isn’t much more than the absorption efficiency of iron from plant foods. And then there’s that rather inconvenient truth that we so often overlook in life: more isn’t necessarily better.

In the past, heme iron was considered superior to non-heme iron because it’s easier to absorb, but in actual fact, heme iron is a little too well absorbed, almost as though the absorption floodgates were being thrown wide open without any thought for caution. The non-heme iron in plants has a much more respectful and cooperative relationship with our body, with its absorption being managed in an extremely efficient and intelligent manner: If your body already has enough iron, your body will decrease absorption, and if your body doesn’t have enough iron, it will increase absorption. This more discerning absorption system is vital, because once iron is in your body, it’s very difficult to get rid of it, and iron excess may well prove a bigger problem than iron deficiency.

Research published in the Nutrition and Cancer journal in 2005 found that ingesting foods rich in heme iron can increase your risk of lung cancer, and a study published in the Journal of the National Cancer Institute in 2008 showed that people who decrease their iron stores by regularly donating blood, cut their risk of dying from gut cancers by 50% over a five year period. The problem is, iron is a pro-oxidant, which means it promotes oxidation. Oxidation is a wearing down or ‘rusting away’ process that damages cells, aging us ahead of time and increasing the risk of chronic disease. To off-set the damaging effects of pro-oxidants like iron, we need plenty of anti-oxidants and plants are antioxidant powerhouses providing, on average, an antioxidant potency 64 times more effective than that of animal-based foods.


Nutritional supplements are big business, a billion-dollar industry that often takes advantage of our rather gullible notion that more of a good thing is surely going to be even better for us. Correcting a deficiency can certainly result in miraculous results, but taking a supplement ‘just in case’ or with the vague idea that all supplements are good for you, is not a wise move. It’s often intrigued me that the list of symptoms associated with a deficiency for any one nutrient can be remarkably similar to the list of overdose signs for the very same nutrient. Health is about balance, after all, with the homeostatic balance systems in our body working hard to keep everything hovering around a midpoint, rather than swinging too far other side.

Quite often, the quantities contained in a supplement can provide over and above the daily dose required for balance, and this is being consumed in addition to iron that is being naturally sourced from whole foods and artificially iron-fortified foods such as commercial breakfast cereals. Ingestion of supplemental iron in even slightly elevated quantities is being associated with increased risk of cognitive problems, and there appears to be a link between iron supplements and Alzheimer’s disease, so please don’t take iron supplements unless you are actually deficient. Once the deficiency has been corrected, maintain your levels with good sources of plant-based iron, combined with synergistic nutrients such as vitamin C rich foods.

From a nutritional perspective, synergy is the way certain nutrients within a food are interlinked and work together as a team, accomplishing far more together than they ever could on their own. Iron, for example, is far better absorbed in the presence of vitamin C. This dynamic relationship between iron and vitamin C is a small love story embedded within a massive web of synergistic relationships involving hundreds of nutrients. To illustrate, you might be thinking you could simply pop a vitamin C pill with meals to enhance your iron absorption, but this would be ignoring the fact that synergism also applies to the vitamin C in this lovers tryst, not just the iron.

Have you heard of the book Whole? The subtitle is Rethinking the Science of Nutrition, by T. Colin Campbell, PhD, with Howard Jacobson, PhD. In Chapter 11, titled Reductionist Supplementation, Colin tells a story about Dr Liu, a research colleague who was curious about exactly what it was in apples that made them healthy for us. Dr Liu and his team started by focusing on the vitamin C content of apples and its antioxidant effect, and they discovered that the vitamin C-like activity from 100mg of whole apple was an astounding 263 times as potent as the same amount of isolated chemical!

“Said another way, the specific chemical we refer to as vitamin C accounts for much less than 1 percent of the vitamin C-like activity in the apple – a minuscule amount. The other 99-plus percent of this activity is due to other vitamin C-like chemicals in the apple, the possible ability of vitamin C to be much more effective in context of the whole apple than it is when consumed in an isolated form, or both…

“If we just take an isolated vitamin C pill, we miss out on the cast of “supporting characters” that may give vitamin C its potency. Even if we add many of those characters into the pill too, which some manufacturers have done with bioflavonoids, we are still assuming that whatever is in the apple and not the pill is somehow unimportant… it is now clear that there are hundreds, if not thousands of chemicals in apples, each of which, in turn, may affect thousands of reactions and metabolic systems.”

In synergism, the supporting characters for the nutritional star of any show are often referred to as co-factors. Vitamin C is a famous co-factor for iron, but there are many, many more. Science has barely scratched the surface when it comes to understanding synergism. There isn’t much point, after all, in researching the synergy of whole foods when whole foods are freely available to the general public and can’t be patented. Who is going to bother funding that, aside from governments? And it’s a lot easier to test a single nutrient than to study the connections between multiple nutrients: science just doesn’t lend itself well to the study of holism because there are too many variables to control for, and how can you study something properly if you can’t isolate it from it’s larger environment?

Research funders want to identify a single ‘active’ ingredient that can be isolated, patented, concentrated and sold back to us with the story that this artificial drug-like substance is somehow superior to the synergistic magic of whole foods. No supplement could possibly replicate the nutrient complexity of whole plant foods, with diverse nutrients in perfect ratio with one another, in a distinctly recognisable form our human body has evolved alongside of since the beginning of our time. Supplements are vital, and they play an important role in correcting deficiencies and protecting those at risk of deficiencies, but they most definitely cannot be thought of as preferable to real food. And just as iron supplements can have a corrosive pro-oxidant effect on the body, so too can supplemental vitamin C (ascorbic acid).


Rich food sources of iron include legumes, tofu, nuts, seeds, wholegrains (esp. amaranth and quinoa), dried fruits and dark green leafy vegetables. While the nutrient levels in seaweeds are often very high our oceans are contaminated with chemicals and heavy metals, so seafoods probably shouldn’t be relied upon as a primary source of nutrition. The iron quantities in the foods listed below are averages, as the nutrient content in any food can vary dramatically depending on variables such as the variety grown and the conditions the food in grown under, not to mention the effects of processing, storage and transport.

8 gm dried weight kombu = 22.1 mg
60g dark chocolate (70-85% cacao) = 7.1 mg
1 cup cooked lentils = 7 mg
½ cup firm tofu = 6.6 mg
8 gm dried weight dulse = 6.4 mg
¼ cup whole sesame seeds = 5.3 mg
1 cup amaranth = 5.2 mg
1 cup cooked chickpeas = 5 mg
1 cup of parsley = 4 mg
½ cup cooked spinach = 3.4 mg
¼ cup chia seeds = 3.3 mg
1 cup of quinoa = 2.8 mg
2 TB tahini paste = 2.7 mg
2 TB pumpkin seeds = 2.5 mg
½ cup of prunes = 2.4 mg
½ cup tempeh = 2.4 mg
1 cup cooked pumpkin = 2.4 mg
½ cup black olives = 2.3 mg
1 cup oatmeal = 2.2 mg
1 cup of kale = 1-2 mg
¼ cup sunflower seeds = 1.9 mg
1 cup fresh chopped basil = 1.4 mg
1 cup cooked broccoli = 1 mg
1 avocado = 1 mg
2 TB cashews = 1 mg
¼ cup dried apricot, coconut or pears = 1 mg
1 cup strawberries = 0.6 mg


As Dr Greger says in his best-selling book How Not to Die, the amount of vitamin C from a single orange can enhance iron absorption “as much as three- to sixfold, so those trying to boost their iron absorption should reach for some fruit instead of a cup of tea.” Vitamin C is found in most fruits and vegetables. Some of the richer sources are broccoli, cabbage, kale, parsley, capsicum, black currants, guava, kiwifruit, mango, orange, pineapple, rockmelon, strawberry, berries, citrus fruit in general, tomatoes, brussels sprouts, cauliflower, snow peas, pawpaw, and melons.

Did you know that the citric acids in citrus fruits also enhance iron absorption? Or that carotenoids, such as the beta-carotenes in yellow, red and orange foods, can increase iron absorption by as much as 300%? Onions and garlic can increase availability of iron from grains and legumes by 50%, and sprouting your legumes before you cook them significantly improves iron availability. Hummus is a classic example of an iron-rich dish full of co-factors that enhance iron-absorption. Iron-rich seeds have great versatility in the kitchen and can be whizzed up with fruit in smoothies or combined with lemon, salt and dairy-free milks to create creamy sauces.

I absolutely love fruit smoothies with a variety of nuts and seeds added, along with organic kale and lemon from my garden. This morning I had frozen bananas with kale, lemon, walnuts, unhulled tahini paste and dates. I wasn’t deliberately looking for anything in particular nutritionally with this mix, but it’s accidentally high in iron and all the cofactors needed to enhance iron absorption. And last night we had pizza with our own homemade ‘cheese’ drizzled over the top: a combination or avocado, cashews, lemon juice, salt and fresh basil from the garden… another really good example of iron mixed with absorption-enhancing cofactors.

And just as there are foods that enhance iron absorption, there are foods that hinder iron absorption. Phytates in whole grains and legumes block iron absorption, but luckily, the higher the phytate concentration, the higher the iron content tends to be, so consuming these foods might not impact iron status as much as was first thought. It’s also worth keeping in mind phytates reduce the risk of many chronic diseases, including several kinds of cancer. Of greater concern are inhibitors like coffee, tea, wine, cocoa, and carbonated soft-drinks, all of which should be consumed an hour away from meals to protect ironm absorption. Herbs that inhibit iron absorption include turmeric, coriander, chilli and tamarind.

Iron is absorbed via the stomach and small intestines, so if there are health problems affecting these organs, absorption can be compromised. A classic example is hypochlorhydria, a deficiency in stomach acid. Many people assume we need less acid in our stomach for good digestion but in actual fact stomach acids are vital for the digestion of minerals like iron. This is why antacids can hinder the absorption of iron. A naturopath can help you improve your digestion with herbs like meadowsweet and dandelion, vegan digestive enzymes, and by teaching you improved stress-management skills and better dietary habits.

Aside from antacids, the other medications that can negatively impact iron absorption include bile acid sequestrants, antibiotics, and pain relief medication. If you are concerned about this, please talk to your doctor. A little known, but very common cause of reduced iron absorption is the use of supplements such as calcium, magnesium oxide, magnesium trisilicate, manganese, and zinc, with calcium being the most potent inhibitor on this list.


Each day, tiny amounts of iron are lost in cells shed from our skin and from the inner lining of the intestine, and for women of childbearing age, the losses are even higher due to menstruation. Some of these losses are off-set by the body’s remarkable recycling skills, with old red blood cells being down as they age so that the iron can be reclaimed and new blood cells built.

Aside from a dietary deficiency, or absorption problems, an iron deficiency can be caused by chronic inflammation, kidney disease or bleeding. Examples of bleeding include heavy periods or chronic bleeding from the gut lining, as might occur when food sensitivities irritate the gut lining. Children, teenagers, pregnant mothers and athletes, all use up their iron stores faster, and these losses need to be replaced.

A nutrient deficiency never has just one single consequence or symptom. Every nutrient and phytochemical has a bewildering number of functions it plays a role in, within the body. Imagine a complex domino effect that ripples throughout the body. It’s important to note that there are other consequences for iron-deficiency besides anaemia, and that you can be iron-depleted without being anaemic. Iron deficiency may cause (or be associated with):

Breathing difficulties, your heart skipping beats on exertion, fatigue, exhaustion, muscle weakness, difficulty concentrating, forgetfulness, sleeplessness, dizziness, cold sensitivity, itchiness, chronic dull headaches, restless legs, poor immunity (eg recurrent infections), burning mouth syndrome, mouth ulcers, sore inflamed tongue, difficulty swallowing, strange cravings eg ice or clay, hyperactivity, irritability, low self-esteem or loss of assertiveness, poor appetite, pale skin, and or brittle, flattened or spoon-shaped fingernails,

There are many different kinds of tests your doctor might use to check your iron levels. A serum iron test measures the amount of iron in your blood, but because the level of iron in your blood can be normal even if the total amount of iron in your body is low, other iron tests may also be done. A Haemoglobin test shows the amount of haemoglobin in the blood. Blood normally contains 12-18 g/dl of haemoglobin. Iron deficiency anaemia occurs when blood haemoglobin drops below this range.

A hemocrit test is a measure of how much space red blood cells take up in your blood, and a serrum ferritin test measures your stored iron. Vegans and vegetarians typically have lower ferritin stores. Having lower serum ferritin doesn’t affect how you feel and isn’t an issue so long as your diet continues to replenish lost iron. In fact, having lower serum ferritin may be an advantage that protects you from diabetes, coronary artery disease, colon cancer and inflammatory conditions. It also optimises your absorption of iron.

When athletes first begin an aerobic training program, their serum ferritin and haemoglobin levels often drop, a condition referred to as ‘sports anaemia’. This beneficial, temporary adaptation to exercise is caused by an increase in blood volume and a resultant dilution of red blood cells, and shouldn’t be confused the true iron deficiency and doesn’t impact on the athlete’s performance. If the test results continue to score low as time goes by and there are obvious signs of deficiency, supplementation may become necessary.

Iron deficiency is the most common deficiency for athletes, and is something to be particularly conscious of if you are a female endurance athlete, or a runner. Female athletes obviously have greater iron loss due to menstruation and distance runners are thought to have an 70% greater need for iron because high-impact exercise (especially the foot striking the ground in running), ruptures red blood cells. Iron is also lost during intense endurance activity through sweating.



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