Focus on Nutrients Part: 2 Iron (Fe)
One of Three Reference Charts To Be Utilized With My Focus on Nutrients Series
If you are intending to reference these please start with my Focus on Nutrients Part: 2 Introduction or access the full series below. I have also included the links to the other two charts for your convenience.
Iron (Fe) For Dog Food
Iron is an essential trace mineral for all life, including animals, plants, bacteria and fungi. It is the most prevalent trace mineral in the animal body, with about 67% of iron found in hemoglobin, the protein in red blood cells that carries oxygen throughout the body.
Why Is Iron an Essential Trace Nutrient?
“Essential” means two things: Dogs can’t live without iron, and they can’t make it from other nutrients. That means it’s vital that they consume iron in the diet, especially during growth phases.
“Trace” means that iron, like zinc, manganese, copper, selenium and iodine, is required only in small amounts, usually measured in parts per million (mg/kg) or parts per billion (µg/kg).
The Two Forms of Iron Found in Pet Foods
Iron comes in two forms in foods:
- Heme iron is found only in meat and other animal products.
- Non-heme iron is found in plant foods and in animal products. (Animal meats contain both heme and non-heme iron.) Most iron supplements also contain non-heme iron.
What’s the difference? Heme iron, including organically bound iron (proteinates, amino acid chelates), is more bioavailable — meaning it’s more easily absorbed by mammals. Non-heme iron (like the inorganic forms found in most supplements) are less bioavailable. In my opinion, it’s best to avoid foods that add iron oxide or iron carbonate due to poor bioavailability.
As with all nutrients, small amounts are essential. For most healthy organisms, a wide range of acceptable amounts exists. However, too much can be detrimental — and even deadly.
You’re probably wondering how to ensure your dog gets the right amount of iron in their diet. In this blog post, I’ll provide a brief primer on iron — why it’s important, where it’s found, and why it’s so challenging to ensure your pet gets enough. Then, I’ll cover two topics:
- If you make your own dog and cat foods, I’ll show you how to how to at least meet American and European minimum recommended amounts of iron for puppies and adult dogs.
- If you make foods for dogs and cats with diabetes, I’ll provide tables listing foods with the least iron per gram of protein, allowing you to formulate moderate, balanced protein, low-iron diets. These tables are not available elsewhere.
Armed with this information, you’ll be well on your way to ensuring your pet consumes the right amount of iron for their lifestage.
Adult dog food recipes:
If you follow the guidelines in these blogs, and build lean meat-based with organs diets, adult recipes for ruminant meats and poultry meats will meet AAFCO and FEDIAF recommendations for iron and I recommend not adding supplements with iron unless your veterinarian recommends it. (Note that the iron is some supplements is indicated by the word ferrous, meaning containing iron, or ferric.)
Growth dog food recipes:
If you are following our guidelines, here’s how to add iron rich foods to your recipes to meet AAFCO, and FEDIAF growth recommendations.
Needs 5 mg per 1000 kcal
Beef spleen, with 439 mg of iron per 1000 kcal, is the most iron-rich food we can get. Add about ¼ pound of beef spleen to the 5,100 kcal recipes (about 7 pounds). If you cannot find spleen, replace 1.5 pounds of 90% lean with beef hearts, separable fat removed.
Chicken growth –
The 5,300 kcal chicken recipe needs 6 mg of iron per 1000 kcal or about 32 mg. (If one is not feeding sea foods, a little more). Chicken liver has moderately-high amounts of iron, and, unlike ruminant liver, is not extremely high in copper, so we add 0.75 lbs. of chicken liver to the recipe and remove 0.75 pounds of the thigh meat. The recipe now contains 1.25 pounds of chicken liver.
The table below lists high and low iron foods. Those wanting to add iron to their dog’s or cat’s diet, choose the high iron options. Those wanting to reduce iron consumption, choose the low iron per 1000 kcal options.
How to Ensure Proper Iron Amounts in Homemade Pet Foods
Providing adequate iron is a concern for all pet owners. Most of the iron in prey and domesticated animals is in the blood. In a pet’s ancestral in their ancestral — or natural — diet, the blood and spleen from prey animals provided much of the iron.
Unfortunately, for most diet makers and commercial companies producing with human-grade standards, blood is difficult to obtain. And today’s dogs rarely eat the most iron-rich organs. If you are a homemade dog food maker, it’s vital to ensure your dog consumes proper amounts of iron.(Note: Iron is some supplements is indicated by the words ferrous or ferric.)
Here’s how to use the tables below:
You need to add 5 to 6 mg of iron for every 1,000 kcal in our basic recipes. The best way to do this is to add foods with the most iron per calorie: those foods listed on the top of Table 1.
- Column 1 lists the food. Most of the data is from the USDA nutrient database. It refers to raw food unless otherwise noted.
- Column 2 lists the amount of iron per 1000 kcal. See what is 1,000 kcal below.
Example: Beef spleen contains 439 mg of iron per 1000 kcal. With spleen, it doesn’t take a lot of calories to provide sufficient iron for growth stages. On the other hand, fatty beef contains only 5 mg of iron per 1000 kcal. Growth minimum recommendations are 22 mg of iron per 1000 kcal. You can’t just feed fatty beef to meet minimum iron requirements.
- Column 3 lists the number of grams of the food that contains 1 mg of iron.
Example: 2.25 grams of spleen contains 1 mg of iron. In our guidelines for building balanced adult growth recipes, we recommend adding 5 to 6 mg of iron per 1000 kcal in the recipe. If you can feed spleen, add 6*2.25 g = 13.5 g or just about ½ ounce of spleen. 60 grams, about two ounces, of fatty beef contain 1 mg of iron.
- Column 4 lists the number of Calories (kcal) in the food for 1 mg of iron.
Example: Adding 1 mg of iron from spleen requires just 2.25 grams of spleen and contains 2.3 kcal. Spleen is a very calorie-efficient way of ensuring your puppies consume sufficient amounts of iron. On the other hand, it takes 201 calories of fatty beef for every 1 mg of iron. Feeding fatty beef is not a good choice for adding iron to your puppy’s food
- Column 5 lists the mg of iron per gram of protein. This is of value primarily for dogs and cats with diabetes. See Table 2 below.
Table 1: Iron Content Of Foods
Note: All natural foods vary, and these numbers are approximate only.
- 1 Average of USA and NZ data
- 2 Separable fat removed
- 3 Average for cooked wild salmon varies by species, geographic location, time of year, and other factors.
Formulating Diets for Dogs With Diabetes
For dogs with diabetes, it’s best to consume moderate protein, low-heme iron content foods. To make foods with moderate amounts of protein with balanced amino acid profiles (animal sources provide the best amino acid balances) and low heme-iron content, choose the foods near the top of the table.
If your dog’s veterinarian recommends that you feed a low iron, moderate protein meat-based diet, choose ingredients with the least amount of iron (Fe) per gram of protein, on the top of the table.
One can estimate that 50 percent of the iron in most animal meats in heme iron. The limited data I’ve seen suggest 40 percent to 55 percent is heme iron, with a lot of variation by season, species, feeding practices, and other factors.
Table 2: Foods With Least Iron per Gram of Protein
- Column 1 lists selected low iron foods.
- Column 2 lists the amount of iron (Fe) in mg for 100 grams of protein from that food.
- Column 3 lists the amount of the food that contains 100 g of protein.
- Column 4 lists the amount of Calories (kcal) consumed for that 100 g of protein.
What Is 1,000 Calories (kcal)?
Calorie consumption varies, but here are a few standards to keep in mind: A typical 40-pound adult dog consumes 1,000 kcal per day. A typical 8-pound cat consumes about 400 to 500 kcal per day.
Here’s what 1,000 calories worth of food looks like:
- 1000 kcal of ground beef, raw
- 93% lean, 1 pound, 8.5 oz. (703 g)
- 90% lean, 1 pound, 5 oz. (600 g)
- 85% lean, 1 pound, 1 oz. (482 g)
- 70% lean, 2/3 pound (300 g)
- 1000 kcal of typical vegetable, raw
- 12 pounds
- 1,000 kcal of my typical recipes, with 13% vegetables
- 1.5 to 1.6 pounds
Steve Brown is a dog food formulator, researcher, and author on canine nutrition. In the 1990s he developed one of the leading low-calorie training treats, Charlee Bear® Dog Treats, as well as the first AAFCO-compliant raw dog food. Since 2003 he has focused on research and education. He is the author of two books on canine nutrition (See Spot Live Longer, now in its 8th printing, and Unlocking the Canine Ancestral Diet (Dogwise Publishing, 2010); and a 40-page booklet, See Spot Live Longer the ABC Way.