IntroductionIt’s been several years since I’vetalked about iron supplementation. Vita-mins and minerals aren’t very glamorous,and nobody really gets too excited aboutthem. They are however very importantand should form the core of any supple-ment program. Iron deserves special at-tention because athletes are at increasedrisk for iron deficiency, and this can com-promise exercise performance. What youneed to know is not too complicated: takean iron supplement, preferably one madewith heme iron. Alternatively, you can eata lot of red meat, if you don’t mind thefat, or you could eat a lot of liver, if youdon’t mind barfing.Iron Requirements andIron DeficiencyDaily iron losses by the adult maleaverage about 1.0 mg per day. Lossesthrough menses increases the iron require-ments of women to about 1.4 mg per day.
The amount of iron absorbed from foodaverages about 10%, so that means menneed to consume 10 mg and women 14mg per day.When a person absorbs less ironthan is lost, iron deficiency will result. Ifleft uncorrected, this will eventuallyprogress to anemia. Without enough iron,the body cannot manufacture enough he-moglobin. If you look at anemic blood ina microscope, the red blood cells are small(microcytic) and pale (hypochromic) be-cause they don’t contain enough hemo-globin. This condition reduces the oxy-gen carrying capacity of the blood. Inorder to meet the oxygen consumptiondemands of exercising muscle, the hearthas to pump harder and faster to supplythe tissues with a larger volume of oxy-gen-poor blood. (Since anemic blood con-tains less oxygen, the heart tries to com-pensate by pumping a larger volume ofblood per minute.) During maximal exer-cise capacity the heart is already produc-ing maximum cardiac output, so oxygendelivery is ultimately compromised (theheart can only compensate so much). Thisin turn puts an upper limit on exercisecapacity.
How would you feel about train-ing like a demon for six months, or longer,and being absolutely strict on your diet,only to have the top shaved off of yourperformance by less than optimal oxygendelivery? You thought you were doing ev-erything right. Attention to detail is whatseparates first and second place. You thinkthis is a rare problem and that you don’thave to worry about it? Hardly. At least11 studies have looked at iron deficiencyin athletes (these are summarized in ref-erence 1). I took the results of these stud-ies and averaged them. According to thesestudies, 35% of female athletes and 10%of male athletes are iron deficient. Iron deficiency and PerformanceThere is no question that irondeficiency anemia has a significant nega-tive effect on oxygen uptake and exercisecapacity (1). During maximal exercise,cardiac output cannot increase to com-pensate for reduced oxygen transport (1).That is, the heart is already at maximumoutput and cannot compensate any fur-ther. No one questions the reality of thiseffect. In fact, some endurance athletesuse “blood doping” to improve exerciseperformance. This practice involvestransfusion of blood one or two days priorto an event to increase hemoglobin con-centration to above normal levels.
A moresophisticated approach is to useerythropoetin. Erythropoetin is a hormonemanufactured by the kidneys whichstimulates the bone marrow to producemore red blood cells. Recently the genefor erythropoetin has been cloned and thehormone can now be produced in vitro(in a lab) and is available for use as aninjectable drug.What about mild iron deficiencywhich has not yet progressed to the ex-treme of frank anemia? Iron is requirednot only in hemoglobin, but also in myo-globin (an oxygen transport protein inmuscle cells) and in several enzymes (in-cluding the cytochromes and others)which are involved in energy production.In one study, rats were made anemic byfeeding them an iron deficient diet andthen the anemia was corrected by bloodtransfusion. These rats still had decreasedexercise capacity even though their ane-mia had been reversed, demonstrating thatiron deficiency can negatively affect ex-ercise performance in the absence of ane-mia (1). These iron deficient rats werefound to have reduced enzyme activitiesin the energy producing pathway com-pared to normal rats. Studies in iron defi-cient humans have demonstrated that aslittle as 2 days of iron supplementationtherapy can reduce heart rate during ex-ercise, presumably by increasing oxygencarrying capacity of the blood and thusreducing the work required by the heartto supply oxygen to the body (1).
Fur-thermore, iron deficient adults also havehigher blood lactate levels following maxi-mal exercise than subjects with normalhemoglobin concentrations (1). Lactate isa product of anaerobic metabolism, indi-cating that these individuals were not de-livering enough oxygen to workingmuscles, or were not able to optimallyproduce energy from oxygen. So it ap-pears that even mild iron deficiency whichhas not progressed to the point of anemiacan also impair exercise performance.Dietary IronDietary iron sources are usuallydivided into two general categories: hemeiron and nonheme iron (1). “Heme iron”is iron which is already bound to heme -the red pigment in hemoglobin. Goodsources of heme iron are red meat andliver. White meat chicken and turkeybreast also contain heme iron, but in loweramounts (2). The form of iron found inplants and conventional iron supplements(ferrous sulfate) is not incorporated intoheme and is therefore called “nonhemeiron.” Iron from red meat and liver, in theform of heme iron, is much easier for yourbody to absorb (1-4).
Iron deficiency is associated withvegetarian diets (1). Some vegetables suchas beans, corn, and spinach contain a sig-nificant amount of iron. Unfortunately, ironfrom vegetable sources is poorly absorbed(1). For example, while spinach is rela-tively rich in iron, only 1.4% of iron fromspinach is absorbed. Red meat providesmuch higher amounts of iron per servingthan vegetable sources (2). And liver isan even better source of iron than redmeat. Furthermore, the iron from redmeat and liver – heme iron – is much easierfor your body to absorb (1-4). About 15-35% of iron from red meat and liver isabsorbed (1,2). The higher iron contentof these foods, plus the greaterbioavailability of heme iron, makes redmeat and especially liver much better di-etary iron sources.About 2-8% of nonheme iron isabsorbed, depending on the compositionof the meal (1). Heme iron is chelated(ionically bound) to a special carrier mol-ecule called a porphyrin, which is in turnbound to the protein hemoglobin. Thiscomplex improves iron absorption by thegut to around 15-35% (1). This makes itaround 4 times more efficient (on aver-age) as an iron supplement. Obviously,heme iron is the way to go.Effects of Iron SupplementationIt has been extensively proven in manystudies that iron supplementation will im-prove exercise performance in iron defi-cient anemic athletes (1).
Studies of ironsupplementation in iron deficient but notanemic individuals have yielded mixed re-sults, some showing improvement andsome showing no effect. The studiesshowing no effect were likely performedusing subjects whose iron deficiency hadnot yet progressed to the point of impairedperformance. “Iron status is a commoncause of decreased exercise performancein humans, especially in women…It isstrongly recommended for serious athletes, those whose performance hasreached a plateau, and female enduranceathletes to seek medical consultation fordetermination of iron status. If deficientin any way, iron repletion by dietary ma-nipulation and/or iron supplementation iswise.”This is a direct quote from refer-ence 1. (I couldn’t have said it bettermyself.) The lab tests you’ll need includea CBC (complete blood count), an ironlevel, ferritin level, and iron binding ca-pacity. These tests are necessary to diag-nose anemia and to prove whether or notthe anemia is due to iron deficiency. Thedoctor’s office visit will cost about $40.00and the lab tests will cost about another$200.00 (give or take). While this is thescientific way to go, it turns out to becheaper just to buy the iron supplementand give it a try. Unless you suspect somemedical problem, this is what I generallyrecommend.
You’ll need to give it a trialof about three months to see if it worksfor you.What is “Sports Anemia?”Sports anemia is induced by exercise train-ing – endurance athletes are especially atrisk (2,3). Many times, sports anemia isnot associated with a true iron deficiency.Skeletal muscle fibers are damaged dur-ing intense exercise training and this dam-age must be repaired during the recoveryperiod following exercise. If dietary pro-tein intake is inadequate, the body willdraw on red blood cells, hemoglobin, andplasma proteins as a source of protein torepair the muscles (2,3). If protein intakeis limited, repair of muscle tissue may soakup all of the incoming protein and not leaveenough left to rebuild new red blood cellsat the normal rate. Increased protein in-take may be effective in treating sports-induced anemia (2,3). Often times, an ath-lete experiences a decrease in red bloodcell count and serum iron levels duringthe early phase of training. This could bedue to the fact that aerobic training causesan increase in myoglobin (an oxygen car-rying protein) and cytochrome content ofmuscle tissue and the protein and iron re-quired for their formation could be ob-tained from destruction of red blood cells.In other words, myoglobin (in muscle)may be increased at the expense of he-moglobin (in blood) if protein intake isinadequate. In summary, sports anemia isa form of anemia seen in hard training ath-letes who are often not iron deficient. Eventhough they are getting enough iron, theybecome anemic do to chronic protein de-ficiency (2,3).
You can’t build blood cellswithout protein.What Should I Do?The best iron supplement is onemade from heme iron, because this ismuch more efficiently absorbed (1-4).The only type of supplement made usingheme iron is desiccated liver. Parrillo Per-formance Liver Amino is made using aspecial extraction process which removesall of the fat and cholesterol which is foundin liver. This is really the only way to getheme iron in a significant amount withoutgetting a boatload of fat along with it.We’ve added a special protein to improveit’s amino acid profile, making LiverAmino a source of high efficiency pro-tein as well as heme iron. There is no otherproduct like it on the market. It is alsofortified with dibencozide, a superior formof B-12 which is better absorbed. It alsocontains other cofactors involved in bloodproduction. To complete the picture youshould also be taking Essential VitaminFormula and Mineral-Electrolyte Formula.In addition to iron, you also need vitaminB-12 and folate to manufacture blood cells.Finally, an adequate protein intake is es-sential. If you’re in a negative nitrogenbalance, the other things probably won’tbe able to help. In summary you needheme iron, B-12, folate, and protein. LiverAmino should be considered a first line“essential” supplement for serious endur-ance athletes, especially women. Also, anywomen who are extremely lean, follow-ing a strict diet, or who are having men-strual irregularities should strongly con-sider this supplement.Attention to Detail
1. Wolinsky I and Hickson JF. Nutritionin Exercise and Sport, second edition.CRC Press, Boca Raton, Florida, 1994.(See chapter 11 “Trace Minerals and Ex-ercise,” by Emily Haymes and chapter 14“Nutritional Ergogenic Aids,” by LukeBucci.)
2. Haymes. “Proteins, Vitamins, andIron.” Ergogenic Aids in Sport, Williams,editor. Human Kinetics Publishers, 1983.
3. Whitmire. “Vitamins and Minerals: Aperspective in Physical Performance.”Sports Nutrition for the 90s, Berning andSteen, editors. Aspen Publishers, 1991.
4. Wapnir. Protein Nutrition and MineralAbsorption. CRC Press, 1990.