Iron deficiency symptoms such as fatigue, dizziness, and pale skin may signal low iron levels, and they affect energy, immunity, and concentration.
This article summarizes how iron works in the body, the difference between heme and nonheme iron, practical tips to improve absorption, and simple dietary changes recommended by registered nutritionist Kayla Hu (胡嘉琪).
Iron’s role in the body
Iron is a core component of hemoglobin, the protein in red blood cells that carries oxygen from the lungs to muscles and organs, and returns carbon dioxide to the lungs for exhalation.
Insufficient iron can shrink red blood cells and reduce their oxygen carrying capacity, which can lead to iron deficiency symptoms including persistent tiredness, pale skin, dizziness, and reduced appetite.
Iron also helps with DNA synthesis, nerve signaling, and immune cell production, so long term deficiency may impair concentration, mood, and infection resistance, and it can affect cognitive development in children and adolescents.
Heme iron versus nonheme iron
Heme iron is found in animal foods and is chemically similar to the hemoglobin in our bodies, so the small intestine can absorb it directly. Common sources include lean red meat, shellfish, poultry, fish, and organ meats such as liver.
Nonheme iron appears in plant foods and fortified grains, but it must be converted in the gut before it can be absorbed. Typical sources include dark leafy greens, soybeans and other legumes, whole grains, nuts, seeds, and iron fortified cereals.
How to boost iron absorption
To increase absorption of nonheme iron, eat vitamin C rich foods at the same meal or immediately before or after iron containing plant foods. Vitamin C helps convert nonheme iron into a form the body absorbs more easily.
Examples of vitamin C rich pairings include citrus fruits, kiwi, tomatoes, and bell peppers served with spinach, beans, or fortified cereals. Combining these foods can noticeably reduce iron deficiency symptoms over time when part of a consistent diet.
Avoid consuming known inhibitors at the same time as iron rich foods. Tannins and polyphenols in strong tea, coffee, cocoa, and red wine can bind iron and reduce absorption.
Also separate high calcium foods and supplements from high iron meals, because calcium competes with iron for the same intestinal uptake pathways. For example, have milk or calcium supplements at least one to two hours apart from your main iron sources.
Anemia warning signs and supplementation guidance
Mild iron deficiency without anemia can often improve with dietary changes alone, focusing on increasing total iron intake and prioritizing high absorption sources.
The recommended daily iron intake for many adults is about 18 mg per day. Prioritize heme iron foods such as lean red meat, shellfish, and animal blood products when appropriate, because these sources are absorbed more efficiently than plant based iron.
Vegetarians and vegans should pair plant iron sources with vitamin C rich foods at every meal, and avoid drinking strong tea or coffee with those meals. If symptoms persist or are severe, seek testing and advice from a clinician before starting iron supplements.
About the nutritionist
Information in this article was reviewed by Kayla Hu (胡嘉琪), a registered nutritionist and a member of the Hong Kong Nutritionists Association. She holds a bachelor of science in food and nutritional sciences from Northumbria University in the United Kingdom.
Kayla practices at Kat-Spirit Nutrition Health Centre and focuses on simple, varied meal plans tailored to individual lifestyles. For more, see her clinic page on Facebook: Kat-Spirit Nutrition Health Centre.
