Saturday, 30 March 2013

...And Popeye's Addendum

I had a friend ask for a little more information about properly balancing iron in a plant-based diet, so I thought I'd tack a post script to my comments about protein.

Iron is a very tricky mineral. Too much of it creates toxicity within the body, but too little can lead to anemia.

Essentially, the majority of iron already in our bodies exists within the hemoglobin - the protein of our red blood cells. It helps transport oxygen to tissues and assists in cellular growth. Iron also exists within enzymes and aids in food digestion.

There are two types of food iron: heme and non-heme. Meat sources provide 40% heme iron and 60% non-heme iron. Heme iron is derived from hemoglobin, and is therefore found in animal sources but not in plant sources. Vegan and vegetarian diets are completely without heme iron sources, but this does not automatically equate to an iron deficiency. In fact, studies have shown that those on plant-based diets are at no greater risk of developing iron deficiency than omnivores.

The CDC lists Recommended Daily Values for iron at 15-18 mg/day for teens and women up to menopause, and 8 mg/day post-menopause. Women require so much additional iron before menopause to recoup for mineral loss during menstruation. Men, other than teens between 14-18, require an average of 8 mg/day throughout their lives.

In addition, vegans and vegetarians should give themselves a nice buffer around that average and aim for approximately twice the RDV to compensate for the lack of heme iron.

The Vegetarian Resource Group provides a great list of non-heme iron sources:

Iron (mg)
Soybeans,cooked1 cup8.8
Blackstrap molasses2 Tbsp7.2
Lentils, cooked1 cup6.6
Spinach, cooked1 cup6.4
Tofu4 ounces6.4
Bagel, enriched1 medium6.4
Chickpeas, cooked1 cup4.7
Tempeh1 cup4.5
Lima beans, cooked1 cup4.5
Black-eyed peas, cooked1 cup4.3
Swiss chard, cooked1 cup4.0
Kidney beans, cooked1 cup3.9
Black beans, cooked1 cup3.6
Pinto beans, cooked1 cup3.6
Turnip greens, cooked1 cup3.2
Potato1 large3.2
Prune juice8 ounces3.0
Quinoa, cooked1 cup2.8
Beet greens, cooked1 cup2.7
Tahini2 Tbsp2.7
Veggie hot dog, iron-fortified1 hot dog2.7
Peas, cooked1 cup2.5
Cashews1/4 cup2.1
Bok choy, cooked1 cup1.8
Bulgur, cooked1 cup1.7
Raisins1/2 cup1.6
Apricots, dried15 halves1.4
Veggie burger, commercial1 patty1.4
Watermelon1/8 medium1.4
Almonds1/4 cup1.3
Kale, cooked1 cup1.2
Sunflower seeds1/4 cup1.2
Broccoli, cooked1 cup1.1
Millet, cooked1 cup1.1
Soy yogurt6 ounces1.1
Tomato juice8 ounces1.0
Sesame seeds2 Tbsp1.0
Brussels sprouts, cooked1 cup0.9

There are two main reasons vegetarians and vegans often don't have low iron levels:

1.  their diets tend to include foods with much higher iron contents

For comparison's sake - 100 calories of roasted chicken breast has only 0.6 mg of iron, whereas 4 ounces of tofu contains 6.4 mg of iron.

2.  their diets are also generally higher in vitamin C, which greatly increases the absorption of non-heme iron into the body

Red and green peppers, kiwis, canteloupe, papaya, guava, strawberries, mangoes and pineapple, cauliflower, pea pods, sweet potatoes and Brussels sprouts are all high in vitamin C.

There are even a few foods like broccoli and kale that provide great levels of both iron and vitamin C in one delicious little package!

Simple combinations like baked tofu and broccoli, or raw peppers and cauliflower with chickpea hummus are easy ways to keep your body well-stocked in both non-heme iron and vitamin C.

A final word about iron supplements...

If you're feeling weak, tired, unable to concentrate or constantly cold, talk to your primary care physician and before jumping on the iron supplement ship. A doctor can perform necessary blood tests to assess your current iron levels, and help you determine the best way to increase your iron stores.