By Jill Castle, Registered Dietitian and Child Nutrition Expert
Popeye the Sailor Man got it right. By focusing on iron (spinach), he transformed himself into a strongman, ready to save the day. He knew that iron was an important nutrient to health. While the swimmer won’t experience Popeye’s immediate transformation into a muscle wielding superhuman, he will strengthen his immune system and energy level.
Where iron is and what it does
There are two sources of iron in our food supply: heme iron (from meats and fish) and non-heme iron (from plant foods). While both are absorbed and utilized by the body, heme iron sources are better absorbed than non-heme iron foods.
Iron helps the body transport oxygen to cells. This is important for the swimmer, as a deficiency in iron will limit oxygen delivery to all cells, including the all-important muscles.
How iron needs change and what they are
As swimmers grow, iron needs increase because blood volume expands naturally. Iron requirements are as follows:
9-13 years: 8 mg per day
14-18 years 11 mg per day
9-13 years: 8 mg per day
14-18 years: 15 mg per day
The female swimmer almost doubles her iron needs when puberty hits, this is due to blood volume increases, and blood losses (menstruation).
Signs of not getting enough
Fatigue or lack of energy, paleness, low body temperature, chronic infections/colds, and reduced academic performance are indicators of a potential problem. Iron deficiency is caused by too little iron in the diet and can lead to iron-deficiency anemia. Swimmers who are lacking iron in their diet will need to focus on getting more. Swimmers who have anemia may be prescribed an iron supplement to rejuvenate their iron stores, in addition to an iron-rich diet.
Swimmers and other endurance athletes are at higher risk for iron deficiency anemia. This is due to blood cell breakdown during exercise, making iron more of a concern. Children and teens who are picky eaters, dieters, meal skippers or who have a poor quality diet (heavy on junk, light on nutritious options) are at risk for iron deficiency. Lastly, female swimmers have a double-whammy—greater iron needs with growth and blood loss due to menstruation.
Popeye was strong because he ate his spinach, but other foods offer the swimmer a punch of iron too. Organ meats (liver), red meats, poultry and fish are the richest sources of heme iron and best absorbed by the body. Non-heme iron sources such as beans, tofu, dark leafy vegetables (spinach, kale), fruits (raisins), iron-fortified cereals, quinoa, iron-fortified breads, bagels and muffins, edamame (soy), almonds and cashews require a little help from Vitamin C to boost the iron absorption.
Tips for getting more
• Plan to include iron-rich foods at each meal.
• Vitamin C promotes iron absorption of non-heme sources. Pair citrus juices, fruits such as strawberries and mango, and other sources of vitamin C with plant-based iron-rich foods.
Example: iron-fortified cereal with raisins and a glass of orange juice
• Protein helps iron absorption. When meat is combined with iron sources (the “meat factor,”), absorption of iron increases 2-3 times!
Example: Enchiladas with lean ground beef and beans; steak and spinach
• Worried your swimmer is not getting enough? Try this!
4-6 ounces of orange juice
½ - 1 cup of baby spinach leaves (or kale)
1 cup of frozen berries (raspberries, blueberries, or other)
¼ cup plain Greek yogurt or iron-fortified tofu
Jill Castle, MS, RD, LDN is a registered dietitian and child nutrition expert. She is the co-author of the upcoming (2013) book, Fearless Feeding: How to Raise Healthy Eaters from High Chair to High School, and creator of Just The Right Byte, a child and family nutrition blog. She lives with her husband and four children (one swimmer!) in Nashville, TN.