April 8, 2024 • 17min
#297 - AMA #58: Iron: its role in health, testing methods, and strategies for preventing and managing iron deficiency
The Peter Attia Drive
Key Takeaways
- Iron is essential for many bodily functions, including oxygen transport, enzyme activity, and cellular respiration. About 2% of the human genome encodes for iron-related proteins.
- Ferritin is a key protein for storing iron in the body. Measuring ferritin levels is important for assessing total body iron stores, but it can be elevated due to inflammation even if iron levels are low.
- Iron deficiency is common, especially in women, vegetarians/vegans, and endurance athletes. Symptoms can include fatigue, weakness, pale skin, and shortness of breath.
- Testing for iron status should include serum iron, ferritin, transferrin saturation, and total iron binding capacity (TIBC). Ferritin below 30 ng/mL indicates iron deficiency.
- Dietary sources of iron include red meat, poultry, fish, beans, and fortified grains. Heme iron from animal sources is better absorbed than non-heme iron from plant sources.
- Iron supplementation options include oral supplements and intravenous infusions. Oral supplements can cause GI side effects. IV iron is faster acting but more invasive.
- Too much iron can be harmful, so supplementation should be done under medical supervision. Excess iron increases oxidative stress and inflammation.
Introduction
In this "Ask Me Anything" (AMA) episode, Dr. Peter Attia and his co-host Nick Dennison dive deep into the topic of iron and iron deficiency. They explore why iron is crucial for the body, what happens in iron deficiency, how to test for it, who is most susceptible, and ways to improve iron levels. This comprehensive discussion aims to provide listeners with actionable information about iron metabolism and supplementation.
Topics Discussed
The Importance of Iron in the Body (4:56)
Dr. Attia begins by emphasizing the ubiquity and necessity of iron in the human body:
- About 2% of the human genome encodes for iron-related proteins
- Nearly half of these are heme-binding proteins
- 6.5% of all enzymes in the human body are iron-dependent
- Iron is crucial for oxygen transport via hemoglobin
- Iron is essential for cellular respiration in mitochondria
He notes: "If you forget everything else about iron's importance, just remember this: you're not going to be able to move oxygen around your body without it."
Ferritin: The Iron Storage Protein (7:19)
Dr. Attia introduces ferritin as a key protein for understanding iron metabolism:
- Ferritin is a large spherical protein that stores iron
- Each ferritin molecule can store about 4500 iron ions
- Most ferritin is found in tissues, especially muscle and liver
- Serum ferritin levels are used to assess total body iron stores
He emphasizes: "Take home message number one of this podcast is if your doctors are not checking your ferritin levels, please ask that they do. It's not enough to just know what your iron level is."
Iron Absorption and Metabolism (10:27)
Dr. Attia explains the basics of iron intake and utilization:
- We consume 10-20 mg of iron per day but only absorb about 10% (1-2 mg)
- We lose 1-2 mg of iron per day, mostly through cell turnover
- 75% of absorbed iron goes to red blood cell production
- 10-20% goes into ferritin storage
- 5-15% is used for other enzymatic processes
He notes that iron must be bound to the protein transferrin for transport in the bloodstream, as free iron is toxic.
Testing for Iron Status (14:22)
Dr. Attia outlines the key tests for assessing iron status:
- Serum iron: Measures circulating iron
- Ferritin: Reflects total body iron stores
- Transferrin saturation: Percentage of transferrin bound to iron
- Total iron binding capacity (TIBC): Measure of transferrin
He emphasizes that ferritin is the most important measure but can be elevated by inflammation, so other tests are needed for a complete picture.
Iron Deficiency vs. Anemia (17:15)
Dr. Attia clarifies the difference between iron deficiency and anemia:
- Iron deficiency: Low iron stores (low ferritin) but normal hemoglobin
- Iron deficiency anemia: Low iron stores and low hemoglobin
- Anemia can have causes other than iron deficiency
He notes that iron deficiency without anemia is more common and can still cause symptoms.
Symptoms of Iron Deficiency (22:15)
Dr. Attia lists common symptoms of iron deficiency:
- Fatigue and weakness
- Pale skin
- Shortness of breath
- Headaches
- Dizziness
- Cold hands and feet
- Brittle nails
- Unusual cravings for non-food items (pica)
He emphasizes that these symptoms can be vague and overlap with other conditions.
Prevalence and Risk Factors for Iron Deficiency (24:30)
Dr. Attia discusses who is most likely to be iron deficient:
- Women of childbearing age (due to menstrual blood loss)
- Pregnant women
- Vegetarians and vegans
- Endurance athletes
- People with certain gastrointestinal disorders
- People who have undergone bariatric surgery
He notes that iron deficiency is one of the most common nutritional deficiencies worldwide.
Dietary Sources of Iron (30:30)
Dr. Attia explains the different types of dietary iron:
- Heme iron: Found in animal products, more easily absorbed
- Non-heme iron: Found in plant sources, less easily absorbed
Good sources of iron include:
- Red meat, poultry, and fish
- Beans and lentils
- Spinach and other leafy greens
- Fortified cereals and grains
He notes that vitamin C can enhance iron absorption, while calcium and tannins (in tea and coffee) can inhibit it.
Iron Supplementation (34:45)
Dr. Attia discusses options for iron supplementation:
- Oral supplements: Various formulations available (ferrous sulfate, ferrous gluconate, etc.)
- Intravenous (IV) iron infusions: For severe deficiency or when oral supplements aren't tolerated
He cautions: "Iron supplementation should be done under medical supervision, as excess iron can be harmful."
Side Effects and Precautions with Iron Supplementation (37:45)
Dr. Attia outlines potential issues with iron supplementation:
- Gastrointestinal side effects (constipation, nausea) with oral supplements
- Risk of iron overload, especially in people with hemochromatosis
- Possible increased oxidative stress and inflammation with excess iron
He emphasizes the importance of proper dosing and monitoring when supplementing iron.
Intravenous Iron Infusions (42:00)
Dr. Attia discusses IV iron as an alternative to oral supplements:
- Faster acting than oral supplements
- Useful for severe deficiency or when oral supplements aren't tolerated
- Requires medical supervision and administration
- Potential for more serious side effects (allergic reactions)
He notes that IV iron can be particularly helpful for people with inflammatory bowel disease or after bariatric surgery.
Who Should Consider Iron Supplementation (44:00)
Dr. Attia summarizes who might benefit from iron supplementation:
- People with confirmed iron deficiency (low ferritin, low transferrin saturation)
- Women with heavy menstrual periods
- Pregnant women (under medical supervision)
- Vegetarians and vegans who struggle to get enough iron from diet
- Endurance athletes with low ferritin levels
He emphasizes: "Iron supplementation should always be based on lab results and symptoms, not just because you think you might need it."
Rapid-Fire Questions on Other Topics (50:15)
The episode concludes with Dr. Attia answering several quick questions on unrelated topics:
- His approach to creatine supplementation
- Sodium intake and blood pressure
- Thoughts on writing another book
Conclusion
This comprehensive discussion on iron metabolism highlights the crucial role of iron in human health and the importance of maintaining proper iron levels. Dr. Attia emphasizes the need for appropriate testing, including ferritin levels, to accurately assess iron status. He outlines the various causes and symptoms of iron deficiency, as well as strategies for improving iron levels through diet and supplementation. The episode provides listeners with valuable insights into this often overlooked aspect of nutrition and health, empowering them to take a more informed approach to their iron intake and overall well-being.