Iron and the Low FODMAP Diet
A while ago I was really battling with low iron. Iron tablets weren’t an option for me as they are harsh on my stomach, which is the last thing I needed for my Irritable Bowel Syndrome (IBS)! I have finally got my iron to a healthy level through controlling my diet and making sure I am eating low FODMAP foods that are high in iron. This blog is to help you enhance your iron levels while on the low FODMAP diet. If you need help choosing an iron supplement please talk to your doctor or pharmacist who can make a recommendation based on your medical history.
What is Iron and what happens when we don’t get enough?
Iron is an important mineral needed to produce haemoglobin in our blood, which carries the oxygen around our body (1 2). Iron also helps to support and maintain a healthy immune system (1 2). When our bodies stop getting enough iron, we produce fewer healthy red blood cells. This can cause you to feel tired and lethargic because your body is less able to transport oxygen around (1 2). Low iron can also lead to paleness, difficulty concentrating, impaired performance at work or school, and weaker resistance to illness (1). It is important that if you are experiencing some of these symptoms you go and talk to your doctor.
Where does your body source iron?
There are two major sources of iron:
Haem iron is only found in meat, chicken and fish. This type of iron is more easily absorbed by your body (1 3). Between 15 to 35% of iron in beef and lamb will be absorbed by your body (4).
Non-haem iron is found in eggs, vegetables, grains and fruit. However, this type of iron is harder for your body to absorb (1 3). Research shows that as little as 5% (2-20%) of iron in spinach is usable by your body (4). An interesting fact is that you would need to eat 2kg of silverbeet to get the same amount of iron provided by 100g of lean beef (4).
For Low FODMAP Food Iron Sources see the table the table below.
Do any foods reduce iron absorption?
Calcium rich foods reduce both haem and non-haem iron absorption (6 7 8). Calcium is found in milk, yoghurt, cheese, tofu, sardines, tinned salmon, broccoli, rhubarb as well as other vegetable sources (6 8). Small amounts of calcium (50 milligrams or less) have little effect on iron absorption, however larger servings such as one glass of skim milk (300 milligrams or more) can significantly reduce iron absorption (6 8). So if you want to have a glass of lactose free milk make sure you have it at least an hour before or after high-iron meals.
Eggs contain a protein called phosvitin, which binds to the iron molecules together and reduces your body’s ability to absorb the iron (6 7 8). One egg can cause your body to absorb 28% less iron from your iron-rich meal (6 7).
Foods high in oxalates reduce the absorption of non-haem iron (6 7 8). According to the Iron Disorders Institute “oxalates are compounds derived from oxalic acid and found in foods such as spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb, strawberries and herbs such as oregano, basil, and parsley” (6). This is why even though spinach is high in iron our bodies find the iron difficult to absorb (6).
Polyphenol-rich foods like tea, coffee, and cocoa can also affect iron absorption (6 7 8). Polyphenols or phenolic compounds are antioxidants that help remove damaging free-floating cells from the body (8). Some types of cocoa and tea can reduce iron absorption by up to 90%, while one cup of coffee can reduce absorption by 60% (6). Phenolic acid can also be found in peppermint and some herbal teas, spices, walnuts, raspberries and blueberries (6). It is recommended that you do not consume foods high in phenolic acid two hours prior to, or following, your main iron-rich meal (6).
Phytate is found in foods like walnuts, almonds, sesame, lentils, cereals and whole grains (6 7 8). Phytate is a compound found in fibre and soy protein. Even small amounts of phytate can reduce iron absorption by 50 to 65% (6).
Just because these foods can reduce iron absorption it does not mean you need to cut them out of your diet. Try reducing the amount of these foods you have with your iron-rich meal, and make sure you consume foods that help increase iron absorption.
Do any foods increase iron absorption?
Vitamin C (ascorbic acid) occurs naturally in fruit and vegetables and it can help increase iron absorption (6 7). Just 100 milligrams of ascorbic acid can increase iron absorption from a specific meal by 4.14 times (6). Citrus fruit like mandarins and oranges are good sources of vitamin C (1 9). One orange can provide you with 70 milligrams of vitamin C (9). Vegetables like red pepper/capsicum, tomatoes, collard greens, potato and turnips are all good sources of vitamin C (1 9). Other fruits high vitamin C that can help with iron absorption are strawberries, kiwifruit, and cantaloupe melon (1 9). When adding low FODMAP fruit and vegetables to your meals make sure you stick to the low FODMAP serving sizes recommended by Monash University.
Tips on Improving Iron Absorption from NZ Nutrition Foundation (2015)
- Lean red meat (beef or lamb) is the best source of easy to absorb iron. If possible eat it 3 to 4 times a week. Chicken, pork, and poultry are also good sources of iron, so eat a variety of these to help increase your iron intake.
- Eat vitamin C rich foods (oranges, kiwifruit, capsicum – low FODMAP fruits and veggies) with your meals to help increase the absorption of non-haem iron.
- Have balanced meals that include both haem foods and non-haem foods to increase absorption of iron. For example, adding lean meat to a salad like A Little Bit Yummy does here: Summer Beef Salad.
- If you don’t eat meat and fish then it is important to include foods that are high in non-haem iron. These foods include tofu, cooked lentils and beans. However be aware that some of these foods can be high FODMAP and lead to IBS symptoms (Monash University App, 2014).
- Avoid drinking tea or coffee with meals as it reduces the amount of iron your body absorbs.
How much iron does your body need per day?
You need different amounts of iron depending on your gender and what life stage you are in. Females tend to need more iron than men. The table below shows the recommended daily intake (RDI) of iron needed for each life stage.
Table Sourced from: NZ Nutrition Foundation, 2015
Low FODMAP High Iron Foods
Introducing a variety of these low FODMAP and high iron foods into your daily diet will help you to maintain and enhance your iron levels. The serving sizes listed in the table are from the original sources and may need to be adjusted to stay within the low FODMAP limits. Use the Monash Low FODMAP app to find the appropriate serving size.
| Vegetables |
Serving Size | Iron (mg) |
|---|---|---|
| Spinach (cooked) | 1 cup | 2.5 |
| Swiss Chard (cooked) | 1 cup | 4 |
| Potato with skin (cooked) | 1 medium | 1.3 – 1.9 |
| Turnip (cooked) | 1/2 cup | 1.5 – 1.7 |
| Kale (cooked) | 1/2 cup | 1.3 |
| Bok Choy (cooked) | 1 cup | 1.8 |
| Broccoli (cooked) | 1/2 cup | 0.6 |
| Grains | Serving Size | Iron (mg) |
| Oats (instant & cooked) | 175ml (3/4 cup) | 4.5- 6.6 |
| Millet (cooked) | 1 cup | 1.1 |
| Quinoa (cooked) | 1 cup | 2.8 |
| Meat & Alternatives | Serving Size | Iron (mg) |
| Meat & Poultry | ||
| Duck (cooked) | 75g | 1.8 – 7.4 |
| Venison (cooked) | 75g | 2.5 – 3.8 |
| Beef (various cuts, cooked) | 75g | 1.4 – 3.3 |
| Ground meat (beef, lamb, cooked) | 75g | 1.3 – 2.2 |
| Lamb (various cuts, cooked) | 75g | 1.3 – 2.1 |
| Chicken (various cuts, cooked) | 75g | 0.4 – 2.0 |
| Pork (various cuts, cooked) | 75g | 0.5 – 1.5 |
| Ground meat (chicken, turkey, pork) | 75g | 2.3 – 4.4 |
| Organ Meat | ||
| Liver (pork, cooked) | 75g | 13.4 |
| Liver (chicken, turkey, lamb, cooked) | 75g | 6.2 – 9.7 |
| Liver (beef, cooked) | 75g | 4.9 |
| Kidney (beef, veal, pork, cooked) | 75g | 2.3 – 4.4 |
| Kidney (lamb, cooked) | 9.3 | |
| Fish & Seafood | ||
| Green mussels | 1/2 cup | 7.5 |
| Oysters (cooked) | 75g | 3.3 – 9.0 |
| Seafood (shrimps, scallops, crab, cooked) | 75g | 2.2 – 2.3 |
| Sardines (canned) | 75g | 1.7 – 2.2 |
| Fish (mackerel, trout, bass, cooked) | 75g | 1.4 – 1.7 |
| Tuna, (light, canned in water) | 75g | 1.2 |
| Salmon (canned) | 90g | 2.1 |
| Tarakihi fillet (baked) | 1 fillet | 0.8 |
| Meat Alternatives | ||
| Tofu (cooked) | 100g | 5.4 |
| Pumpkin seeds (roasted) | 1/4 cup | 1.4 – 4.7 |
| Tempeh (cooked) | 150g (3/4 cup) | 3.2 |
| Sesame seeds (roasted) | 1 tbsp | 1.4 |
| Chickpeas (cooked) | 1/4 cup | 0.8 |
| Lentils (boiled) | 1/4 cup | 0.6 |
(Table Compiled from:Dietitans of Canada, 2014; Mangels, 2015; NZ Nutrition Foundation, 2015)
Final Thoughts
It is possible to create a balanced diet full of iron rich food while on the low FODMAP diet. If you are feeling concerned about your iron levels please go and talk to your doctor, as he/she can create treatment options that suit your body.
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