Popeye and spinach: tall story or science?

Latest from Science

I expect everyone reading this has backed Popeye, at least once. This legendary sailor drawn by Elzie Crisler Segar is famed for knocking down his opponents and standing up for the weakest.

And his invincibility, physical strength and speed come from the spinach he eats, from that instantly recognisable can, just before tackling – and annihilating – his enemies. For him, this spinach instantly makes his biceps grow, almost literally turning them to iron!

Power of betaine

We have no idea whether Segar even knew what betaine was, but today we do know betaine, the primary substance in spinach, is used as a supplement in endurance events and high-intensity training. At a daily dose of 500 to 9000 mg/day, betaine might even help treat hyperhomocysteinaemia or alter body composition.

Some studies suggest using betaine supplements could reduce fat mass and/or increase lean mass, making it useful for overweight athletes or patients.

How it works remains unclear

Betaine’s precise mechanism of action isn’t 100% clear, but the following seems fairly certain:

  • It has a lipolytic effect (i.e. reduces fat mass);
  • It helps prevent fat formation;
  • Using a mechanism of action similar to growth hormone, it seems to facilitate the production of IgF1, with an increase in cellular protein synthesis;
  • It has an anti-catabolic action and helps prevent fatigue.

Foods rich in betaine

Betaine is widely known to be found in sugar beet, at a concentration of 250mg/100g, and in spinach, at 600mg/100g, but it is also found in high quantities in wheat bran (1,330mg/100g), wheat germ (1,241mg/100g), and wheat bread (200mg/100g), albeit at quite variable values.



Studies thus far

Numerous studies consider a daily dose of 2.5-5g sufficient to increase plasma betaine concentrations. Likewise, 2.5g/day might well improve performance.


In one study, the effects of acute betaine supplement ingestion were explored during a race, with the competitive marathon athletes slightly dehydrated  (-2.7% of body weight) and in a hot environment. They then rehydrated by consuming 1 l of fluid (with or without 5g/day of betaine) 45 minutes before prolonged treadmill running (75 minutes) at 65% Vo2max and a performance sprint at 85% of Vo2max.


The betaine treatment increased the plasma betaine concentration. Despite no differences in heart rate, body and surface temperature, sweating and lean body mass loss, those athletes who took the betaine supplements showed increased oxygen consumption and sprint duration, supporting the idea betaine enhances physical performance.


A 2011 study demonstrated how consuming betaine for 14 days improved post-exercise skeletal muscle oxygen saturation, compared to a control group.

Betaine in the future

Current literature seems to indicate betaine could be beneficial for medium/high intensity aerobic exercise in hot conditions. There are two reasons for this:


1. It presumably increases maximum muscle oxygen consumption;

2. It effects plasma osmolality.


Both these hypotheses need to be properly tested in the future by targeted studies conducted in stress conditions matching exercise. Let me expand on this point briefly. Supplement studies are often done in closed settings, on a treadmill or exercise bicycle, at constant temperature and humidity. This does not suitably replicate the conditions when exercising outside. Take, for example, running on a mountain trail and think of all the changes in environment and terrain.

Improved strength and power performance…

A 2009 study showed betaine improved performance in strength and power activities. Taking 2.5g/day of betaine supplements for 15 days resulted in improved performance in squat repetitions.

The benefits of betaine for resistance training (I mean weights here) are yet to be clarified.

One study did demonstrate that taking betaine supplements for 14 days increased both the number of reps and the volume during 10 sets of bench press exercises. Nonetheless, the impact of betaine supplements on body composition in men and hypertrophy is limited.



… and body composition

For the first time in 2013, science showed taking 2.5g/day of betaine for 6 weeks can improve body composition when combined with strength training. In the study, the results showed a reduction in fat mass and an increase in lean mass.


The mechanism that causes betaine to have this effect now needs to be more thoroughly investigated.


It might be that betaine can influence body composition by stimulating the secretion of growth hormone and IGF1. In 2012, a study demonstrated taking 2.5g of betaine for 14 days induced an increase in plasma growth hormone and IGF1 and a drop in cortisol concentrations due to physical exercise.

Feeling less tired

There is a theory that betaine has an effect, in endurance sport, on feeling thirsty and on an athlete’s perception of temperature. A 2008 study found it could reduce the sensations of thirst and heat in the final sprint.

Another study in 2011 showed how using the same dose of 2.5g/day of betaine helped reduce the feeling of tiredness during prolonged high-intensity exercise.


Take-home message

In conclusion, a supplement of 2.5g/day of betaine would seem to have positive effects for high-intensity aerobic sports, especially when it’s hot, and for power and strength sports. Finally, there does seem to be some impact on body composition, with a drop in fat mass and an increase in lean mass.


Yet, the literature is seemingly a bit contradictory and so controlled, randomized studies are needed to determine the mechanisms in the body that produce these presumed effects and potential performance benefits.


  • Craig SAS. Betaine in human nutrition. Am J Clin Nutr. 2004; 80:539-549.
  • Borsook ME, Billig HK, Golseth JG. Betaine and glycocyamine in the treatment of disability resulting from acute anterior poliomyelitis. Ann West Med Surg. 1952; 6:423-427.
  • Eklund M, Bauer E, Wamat U1, Mosenthin R. Potential nutritional and physiological functions of betaine in livestock. Nuu Res Rev. 2005; 1,8:31-48.
  • Armstrong LE, Casa DJ, Roti MW, Lee EC, Craig SA, Sutherland JW, Fiala KA, Maresh CM. Influence of betaine consumption on strenuous running and sprinting in a hot environment. J Strength Cond Res. 2008; 22:851.
  • Trepanowski JF, Famey TM, McCarth y CG, Schilling BK, Craig SA, Bloomer RJ. The effects of chronic betaine supplementation on exercise performance, skeletal muscle oxygen saturation and associated biochemical parameters in resistance trained men. J Strength Cond Res. 2011 Dec;25(12):3461-71.
  • Cholewa JM, Wyszczelska-Rokiel M, Glowacki R, Jakubowski H, Matthews T, Wood R, Craig SA, Paolone V. Effects of betaine on body composition, performance, and homocysteine thiolactone. Int Soc Sports Nutr. 2013 Aug 22;10(1):39.
  • Del Favero S, Roschel H, Artioli G, Ugrinowitsch C, Tricoli V, Costa A, Barroso R, Negrelli AL, Otaduy MC, da Costa Leite C, Lancha-Junior AH, Gualano B. Creatine but not betaine supplementation increases muscle phosphorylcreatine content and strength performance. Amino Acids. 2011; 42:2299-2305.
  • Lee EC, Maresh CM, Kraemer WJ, Yamamoto LM, Hatfield DL, Bailey BL, Armstrong LE, Volek JS, McDermott BP, Craig SA. Ergogenic effects of betaine supplementation on strength and power performance. Int Soc Sports Nutr. 2010 Jul 19; 7:27.

An endocrinologist by training, he was a Psychoneuroendocrinology lecturer at Parma University and a Nutrition & Endocrinology lecturer at Pavia University. He is now in charge of the medical division at the Ecomedica clinical research institute and JMEDICAL’s Nutrition and Sports Nutrition department. He has published numerous scientific papers and is President of SINSeB, the Italian sports nutrition and wellness association, as well as the Italian Ambassador and member of the advisory board of the International Society of Sport Nutrition (ISSN). He is in charge of the sport nutrition and supplements department at Vr46 Riders Academy, Empoli Calcio, and Sampdoria, and an endocrinology consultant for the Italian national and U21 football teams, and Juventus FC.