Popeye the Sailor – Man & Spinach

Who hasn’t heard of Popeye the Sailor Man? His strength came from a can of spinach — or did it? Spinach contains nonheme iron, the form of iron that is not readily absorbed unless a person is deficient or it is consumed in combination with heme iron (animal products) or vitamin C. Not only is the form of iron not easily absorbed in spinach, but spinach contains compounds that bind with iron and interfere with its absorption. This article will further explore iron’s absorption and distribution.

Popeye the Sailor, iron, trace minerals, minerals, blood, hemoglobin, anemia, heme iron, nonheme iron, vegetarians, vegetables, absorption, growth, development, animals, meat, RDA, Vitamin C, bone marrow, interference, oxalic acid, tannins, polyphenols, spinach, phytic acid
Tea — Tannins & Absorption of Nonheme Iron

The absorption of nonheme iron is affected by many dietary factors. Oxalic acid in vegetables and phytic acid as well as additional factors found in grain fibers can bind iron and decrease its absorption. In tea, tannins (polyphenols) reduce the absorption of nonheme iron. If someone has an iron deficiency, the intake of tannins should be watched and fiber intake should be kept within current recommendations. Additionally, zinc supplements will interfere with the absorption of nonheme iron since zinc and iron compete for absorption. (1) (2) (3)

Iron Needs & Absorption

The body’s need for iron is the single most important element affecting nonheme iron absorption. Iron needs increase:

  • During growth and pregnancy;
  • During a state of iron deficiency; and
  • At high altitude due to the air’s lower oxygen concentration resulting in the increased concentration of hemoglobin in the blood. (2) (3)

    Popeye the Sailor, iron, trace minerals, minerals, blood, hemoglobin, anemia, heme iron, nonheme iron, vegetarians, vegetables, absorption, growth, development, animals, meat, RDA, Vitamin C, bone marrow, interference, oxalic acid, tannins, polyphenols, spinach, phytic acid
    Colorado Rockies – High Altitude & Iron Absorption

Where there are inadequate iron stores, the main protein that transports iron in the blood easily binds additional iron from intestinal cells, moving this iron into the bloodstream. On the other hand, when there are adequate iron stores and the protein that binds iron in the blood is totally saturated with iron, little is absorbed from the intestinal cells where iron stays bound. (2) (3)

It is through this mechanism that iron, and the nonheme form in particular, is only absorbed as needed under normal circumstances. Intestinal cells have a two to five day life cycle. If iron is not needed, it will be excreted from the iron that is stored in intestinal cells. Even though high doses of iron is toxic, under normal dietary conditions in the majority of people it is carefully regulated. (2) (3)

Popeye the Sailor, iron, trace minerals, minerals, blood, hemoglobin, anemia, heme iron, nonheme iron, vegetarians, vegetables, absorption, growth, development, animals, meat, RDA, Vitamin C, bone marrow, interference, oxalic acid, tannins, polyphenols, spinach, phytic acid
Red Blood Cells & Iron

The hemoglobin molecules of red blood cells contains the majority of iron in the body. The bone marrow stores some, and a small amount is found in other body cells, for example the liver, to store it. The iron found in these body stores can be mobilized if iron is needed. However, these iron stores can be depleted if there is a chronically inadequate intake of dietary iron. (2)

In light of the fact that iron deficiency remains a world wide problem, its absorption is an important factor. Even though a food may be rich in iron does not mean it will be absorbed. The form of iron as well as interference with anti-nutrient compounds and mineral interactions all affect absorption. Taking a specific mineral supplement will interfere with the absorption of other essential minerals. It is for this reason natural supplements are most effective. (2) (3)

(1) https://www.cdc.gov/immpact/micronutrients/index.html
(2) https://www.cdc.gov/nutritionreport/99-02/pdf/nr_ch3.pdf
(3) https://www.cdc.gov/mmwr/preview/mmwrhtml/00051880.htm


Iron Man & Woman – Iron Absorption

“Iron Man & Woman” — For hundreds of years the importance of dietary iron was common knowledge. Despite this understanding, one of the most common worldwide nutrient deficiencies is iron. This is also the only nutrient where the RDA for men is less than the RDA for young women. (3)


Every living cell contains iron, amounting to approximately 5 grams, or one teaspoon for the whole body. Iron absorption is based on a number of factors. This article provides an overview of what factors come into play in its absorption. (2)

Absorption – Controls
Hypertension, Silent Killer, High Blood Pressure, Uncontrollable Risk Factors, Age, Family History, Atherosclerosis, preventable risk factors, obesity, excess weight, inactivity, alcohol.
Hypertension – The Silent Killer — Exercise Makes a Difference

Once iron is absorbed it is not easily eliminated from our bodies, therefore, it is important to control iron absorption. Several mechanisms exist to regulate our body’s ability to absorb iron. Generally, iron absorption depends on:

  • the body’s need for iron,
  • its form in a particular food,
  • and many other factors.

Healthy people absorb approximately eighteen percent of the iron present in food, however people who are iron deficient absorb more. (2)

Absorption – Form Counts
Steak – Heme Iron

Iron is found in different forms based on the food. The amount absorbed is influenced by the particular form. Within animal flesh, approximately forty percent of the total iron is:

  1. hemoglobin, the form that is found in red blood cells, and
  2. myoglobin, the pigment that is present in muscle cells.

This kind of iron is referred to as heme iron and is absorbed approximately 2 – 3 times better than nonheme iron (the simple elemental iron). Nonheme iron is the form that is added during the enrichment process to grain products. It is also found in:

  • animal flesh,
  • milk,
  • eggs,
  • grains,
  • vegetables, as well as
  • other plant foods. (2) (3)

    Citrus Fruit – Increases Absorption of Nonheme Iron

Consuming nonheme iron with heme iron together increases the absorption of nonheme iron. Consuming more vitamin C rich foods will increase iron absorption, especially if blood iron is too low or there is inadequate dietary iron. Copper also aids with the body’s iron use.

Iron is the oldest known trace mineral critical for the growth and development of the human body. A number of factors influence its absorption, including its form (whether heme or nonheme) as well as other foods with which it is consumed. The body of knowledge is vast and this article just touches upon its absorption. The next article will further delve into what affects its absorption and its distribution.


Take Heart with Potassium

Take heart with potassium… . In order to live, you need minerals. Not just any mineral — eating dirt won’t be helpful, but everyone needs those major and trace minerals required for basic life functions. This article will take an in-depth look at the major mineral, potassium.

Heart Health: Potassium and Sodium

Potassium and sodium share many of the same life functions, namely transmission of nerve impulses and fluid balance, but in different locations. Where sodium operates outside the cell, potassium operates inside. Fluids found inside the cell (intracellular fluids) contain most of the potassium found in the body — 95%.

Your Blood Pressure: What’s Healthy – What’s Not

Additionally, where sodium intake increases blood pressure, potassium lowers blood pressure. Potassium is a critical element for cardiovascular function. (1) (2)

A person who has low blood potassium is in a life-threatening situation. Often, symptoms include:

  • muscle cramps,
  • loss of appetite,
  • constipation, and
  • confusion.

Eventually the heart will beat irregularly, thus decreasing its ability to pump blood. (1) (2)

Potassium Needs:
potassium, trace minerals, microminerals, sodium, hypertension, heart health, blood pressure, heart, intracellular fluids, processed food, unprocessed food, minerals, vegetables, fruits, whole grains, milk, meats, and dried beans, kidneys, minerals
Whole Grains – Mineral Rich

Adults need to consume 4700 milligrams (4.7 grams) per day in order to fulfill the Adequate Intake for potassium requirements. The food and supplement labels use the Daily Value based on 3500 milligrams. Although approximately 90% of the potassium we eat is absorbed, the average North American only consumes 2000 to 3000 milligrams of potassium per day. Most need to increase their intake. (3) (4)

Where sodium is often added to foods, potassium is not, contributing to a lower intake. Also, those with high blood pressure being treated with diuretics are at risk of depleting their body’s potassium stores. Therefore, people who take diuretics waste their body’s potassium and must carefully monitor their intake of this mineral. Foods high in potassium are healthy additions to their diets. (3) (4)

potassium, trace minerals, microminerals, sodium, hypertension, heart health, blood pressure, heart, intracellular fluids, processed food, unprocessed food, minerals, vegetables, fruits, whole grains, milk, meats, and dried beans, kidneys
Take Heart with Potassium – The Role of Your Kidneys

No Upper Level for potassium is set since potassium toxicity is not a risk with typical food intakes as long as the kidneys function properly. Those with unhealthy kidney function, however, are at risk for the build up of potassium in the blood. This prevents the heart from functioning and slows the heartbeat. If left untreated, it results in death. (3)

Potassium Sources:

The most healthy way to meet your potassium requirements is by increasing the consumption of foods rich in potassium. Unprocessed foods are generally rich sources of potassium, including vegetables, fruits, whole grains, milk, meats, and dried beans. (4) (5)

What’s your favorite potassium rich food? Do you have a recipe to share?


1. https://www.cdc.gov/salt/index.htm
2. https://www.cdc.gov/media/releases/2011/p0711_sodiumpotassiumdiet.html
3. https://www.nal.usda.gov/fnic/dietary-reference-intakes
4. https://health.gov/dietaryguidelines/2015/guidelines/
5. https://health.gov/dietaryguidelines/2015/guidelines/appendix-10/

Interactions: Interference with Mineral Need

scientific laboratory
Scientific Laboratory

Interactions can interfere with mineral needs. Without certain minerals, you cannot sustain life. And, just because a food is rich in a mineral, does not mean you will garner its benefits. Such is the case when it comes to mineral interactions with fiber and mineral interactions with each other. This article will explore these interactions.

Fiber Interactions:
Grain Products
Grain Products

When it comes to fiber, certain substances can bind to the mineral preventing its absorption. In particular, grain fiber contains a compound called phytic acid which binds to minerals limiting its absorption. Another plant substance that binds minerals, especially calcium, is oxalic acid, found in high concentrations in spinach, thus severely limiting the absorption of this mineral. Accordingly, diets high in fiber can limit the body’s absorption of zinc, iron, and other minerals. The current recommended intake of fiber is 25 grams for adult women and 38 grams for adult men. A higher intake could create problems with the body’s mineral status.

Mineral Interactions
minerals, supplements, lab
Mineral Supplements are Manufactured in the Lab

With respect to mineral interactions with each other, this problem arises most frequently with those taking a specific mineral supplement. This is because several minerals, such as

  • calcium,
  • magnesium,
  • copper, and
  • iron

are similarly sized with similar electrical charges. These similarities create a competition among them for absorption affecting their bioavailability. In other words, if one of these minerals are taken in excess, it decreases the absorption of the others. For example, copper absorption is decreased with an excessive intake of zinc. For this reason, individual mineral supplements should be avoided unless recommended by a health professional due to a medical condition or dietary deficiency. On the other hand, food sources, pose little risk for mineral to mineral interactions.

Farmer's Market Fresh, vegetables
Fresh from the Farmer’s Market – Vegetables – A Great Source of Vitamins and Minerals

The bottom line is that there is minimal threat of interference in absorption caused by phytic acid and oxalic acid, two compounds found in high fiber foods and vegetables, with natural foods rather than pills. When you use a natural food product, mineral to mineral interactions is not an issue.

(C) 2016 Karen Van Den Heuvel Fischer

Minerals — The Bottom Line

Can you live without minerals? Like vitamins, minerals are required to sustain life. They are needed for the body’s basic life functions at every level starting at the cellular and continuing through to the tissues, organs, and the whole body. The roles each mineral plays and the amounts required to effectively perform their function varies.


For example, some minerals like selenium and copper work as cofactors. In their function as a cofactor, minerals permit enzymes and other proteins to function. Additionally, minerals are key contributors to a variety of body compounds. Examples of such body compounds are red blood cells, of which iron is an important component. Other functions in which minerals such as phosphorus and calcium play a critical role is the development and growth of the body. Water balance also requires minerals. Without calcium, phosphorus, potassium and sodium, there is no water balance causing a life-threatening state. How are minerals categorized, and how readily available are they?

Fishing with Popsy - Enjoying the Water
Salt Water Fishing

The amount of minerals required per day is the method used to categorize minerals. Minerals that require more than 100 milligrams per day, or 1/50th of a teaspoon is categorized as a major mineral. Examples of major minerals include calcium and phosphorus. Those that require less, like zinc and iron are classified as a trace element. But just because a food is rich in a much needed mineral, doesn’t make it useful. Our bodies may not be able to absorb and use them. And, just because a certain mineral content is listed for a particular food on a table, does not mean it is a good source for that mineral. It actually is only a starting point. For example, there is a high concentration of calcium found in spinach. Unfortunately, spinach also contains a high concentration of the calcium-binder, oxalic acid, resulting in the absorption of only about five percent of the calcium consumed.

Jerusalem Shuk - Breads
Jerusalem Shuk – Breads

Generally speaking, as the refinement of a plant food increases, the mineral content decreases, an example of which is refined flour. When a grain product is refined, the only mineral added during the enrichment process is iron. Other minerals, such as copper, selenium, and zinc are lost and not replaced. To answer the question we started with, “Can you live without minerals?”

The answer is clearly NO.

What is your favorite whole grain recipe?

(C) 2016 Karen Van Den Heuvel Fischer