Where is heme found

Therefore, heme ought to be a crucial factor when considering human nutrition and health. This review summarizes both epidemiological and molecular studies regarding heme function in health and diseases.

It can serve as a starting point for further discussion of heme function as an essential nutrient and investigation of heme function in the pathogenesis of diverse diseases. National Center for Biotechnology Information , U. Journal List Nutrients v.

Published online Mar Author information Article notes Copyright and License information Disclaimer. This article has been cited by other articles in PMC. Keywords: heme intake, iron, red meat, cancer, diabetes, coronary heart disease, hemoproteins, cancer progression. Introduction Proteins are the building blocks of life. Dietary Heme Is Efficiently Absorbed in the Small Intestine Heme is found in highest abundance in meat in the form of hemoglobin and myoglobin.

Open in a separate window. Figure 1. High Heme Intake Is Associated with Increased Risk of Cancer Dietary differences in the world likely contribute to global variations in cancer cases [ 43 ]. Risk of Gastrointestinal and Pancreatic Cancer Is Associated with High Heme Intake With the availability of large amounts of epidemiological data for colorectal cancer, the positive relation between colorectal cancer and high intake of red meat high heme content is convincing; however, limited data is available for other gastrointestinal malignancies.

High Heme Intake Increases the Risk of Endometrial Cancer in Women Endometrial cancer accounts for 10—20 per 10 5 people a year in western countries [ 62 ]. Epidemiological and Molecular Studies Reveal the Link between High Heme Intake and Lung Cancer Several case control and cohort studies have been reported for an association between high meat or heme intake and risk for lung cancer, but these limited studies show inconsistent findings [ 49 ].

Figure 2. High Heme Intake Correlates with Increased Risk of Type-2 Diabetes Previous epidemiological studies have suggested an association between high heme iron intake and diabetes, as well as coronary heart disease. Heme Deficiency Can Cause Serious Health Problems in Humans While high dietary intake of heme may have adverse effects on health, heme deficiency can also cause serious health problems. Defects in Heme Biosynthesis Can Cause Anemia and Porphyrias in Humans Heme biosynthesis involves eight enzymes, and a defect in any one of them is associated with diseases.

Heme Regulates Diverse Neuronal Genes Heme is involved in the regulation of neuronal specific genes, particularly through the NGF signaling pathway [ 98 , ]. Conclusions This review offers a comprehensive analysis of the current literature on the health benefits and risks of heme as an essential nutrient. Conflicts of Interest There are no conflicts of interest. References 1. Briat J. Iron utilization and metabolism in plants.

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Natural chlorophyll but not chlorophyllin prevents heme-induced cytotoxic and hyperproliferative effects in rat colon. Dietary haem stimulates epithelial cell turnover by downregulating feedback inhibitors of proliferation in murine colon. Tasevska N. No effect of meat, meat cooking preferences, meat mutagens or heme iron on lung cancer risk in the prostate, lung, colorectal and ovarian cancer screening trial. Qiao L. Intakes of heme iron and zinc and colorectal cancer incidence: A meta-analysis of prospective studies.

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Body iron stores and heme-iron intake in relation to risk of type 2 diabetes: A systematic review and meta-analysis.

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Bran fiber, large amounts of calcium particularly from supplements, and plant substances like phytates and tannins can inhibit the absorption of non-heme iron. There are several types of iron available as over-the-counter supplements, e. Confusion is also caused by two number amounts listed on the label, a higher number and a lower number.

What is the difference among supplement forms and which number should you refer to for the right amount to take? Elemental versus chemical form of iron. If two iron amounts are listed on the label, the larger number is the chemical compound form because iron is bound to salts e. Elemental iron is the more important number because this is the amount available for the body to absorb.

However, a physician may not specify in a prescription if the iron amount is the chemical form or the elemental iron. For example, a ferrous sulfate iron supplement may list a total of mg of ferrous sulfate on the front of the label but 65 mg of elemental iron in smaller print on the back. If a physician prescribed 65 mg of iron, would you take five pills to equal mg, or just one pill, assuming the prescription referred to elemental iron?

Different types. All types of supplemental iron help to increase red blood cell production but vary in cost and amounts of elemental iron. Ferrous gluconate is usually sold in liquid form and some clinical studies have shown that it is better absorbed than ferrous sulfate tablets.

However, ferrous gluconate contains less elemental iron than ferrous sulfate, so a greater dosage may be needed to correct a deficiency. It is also more expensive than ferrous sulfate. Newer slow-release forms of iron have been introduced, which may help reduce gastrointestinal side effects, but they are more expensive and usually contain less iron.

Any confusion with iron supplement types and amounts can be resolved by asking your doctor to specify both the elemental amount and the chemical compound amount. An iron deficiency is seen most commonly in children, women who are menstruating or pregnant, and those eating a diet lacking in iron. Iron deficiency occurs in stages. If this does not resolve, the next stage is a greater depletion of iron stores and a drop in red blood cells.

Eventually this leads to iron-deficiency anemia IDA where iron stores are used up and there is significant loss of total red blood cells. Typically, a doctor screens for anemia by first checking a complete blood count including hemoglobin, hematocrit, and other factors that measure red blood cell volume and size.

If this is below normal, ferritin and transferrin levels may be measured to determine if the type of anemia is IDA there are other forms of anemia not caused specifically by an iron deficiency. All of these measures would decrease with IDA. IDA is usually corrected with oral iron supplements of up to mg of elemental iron daily. Those at high risk of IDA may be prescribed mg daily.

But on the other hand, that same knowledge can be used to help reduce the iron absorbed from our meals. We should be very conscientious about including the nutrients that impair non-heme iron and one that also impairs heme iron! In a more general sense, the following is a highest-to-lowest list of foods that typically have a high amount of heme iron:. The following is a highest-to-lowest list of foods that typically have a high amount of non-heme iron:.

We all have to eat, and many nutritious foods contain iron in them. Therefore it is important to understand heme iron vs. Sign-up today for in-depth and empowering articles with actionable tips to assist you on your journey with hemochromatosis! By Dr. In This Article:. Making Dietary Choices When You Have Hemochromatosis In a diet for iron overload, it is important to understand which foods you should pay the most attention to. The two forms of dietary iron are heme iron and non-heme iron: Heme iron is found only in meat, poultry, seafood, and fish, so heme iron is the type of iron that comes from animal proteins in our diet.

Non-heme iron, by contrast, is found in plant-based foods like grains, beans, vegetables, fruits, nuts, and seeds. Another way to think about Heme vs. Non-Heme is by categories of foods: Animal meat is a combination of heme and non-heme.

Dairy and eggs are non-heme. Plant foods are non-heme only. The way our body absorbs these two types of iron is very different: Heme iron is more easily absorbed and is, therefore, a large source of dietary iron for people both with and without hemochromatosis. Non-heme iron is usually less readily absorbed than heme iron.

Especially in people without hemochromatosis, non-heme iron tends not to be a big source of dietary iron. Why Does Heme vs. Non-heme Iron Matter in Hemochromatosis?

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