“I’m Popeye the Sailor Man,
I’m Popeye the Sailor Man.
I’m strong to the finish
Cause I eat me spinach.
I’m Popeye the Sailor Man.”
We all know the jingle and the infamous 'bowling pin' forearms that us guys all wish we had. In fact, I think you'd struggle to find any young boy who's watched a couple of episodes of Popeye and didn't want to grow up wishing he had those muscles. In fact it's been noted that during the first decade Popeye was aired sales of spinach increased by 30%. Moreover, a recent study (2010) noted that children were more inclined to eat spinach, and doubled their daily vegetable intake after watching an episode of Popeye.  Traditionally Popeye consumed his trusty can of spinach to help him become strong enough to fight off different villains, like Bluto. But is there any scientific basis for Popeye’s trust in spinach?’ Spinach has is known as a 'superfood, meaning it contains all the vital vitamin sand minerals the body needs. It's typically high in calcium, copper, foliate, omega 3, vitamin A, B6, B12, vitamin C, E, K zinc ,and well the list goes on. But what it's most famous for is its high levels of iron.
Despite claims of spinach being super high in iron, the science Professor Von Wolff who carried out the research on its iron content actually misplaced the decimal point, claiming it was 10x higher in iron that is actually was . This myth continued on for more than 50 years before Professor Von Burge discovered the error with Professors Bender & Hamblin, who finally published the ‘Spinach, Popeye Iron, Decimal, Error Story (SPIDES),’  and that spinach has no more iron than any other leafy vegetable . In fact, spinach contains more Vitamin A and magnesium than it does iron and it was this that was thought to have contributed to Popeye's level of strength, not the iron.  Despite all of these great things, it's not iron, vitamin A, nor magnesium I want to talk about, but rather I want to direct your attention to two other nutrient 'bombshells' that Popeye may have known about and kept secret from Bluto.
Spinach belongs to the Amaranthaceae plant family, which is known to contain a steroid-like substance called ecdysterone . Ecdysteroids are a class of compounds that are structurally similar to androgens (male sex hormones) and have been cited by some researchers as "behaving similar to anabolic steroids putatively without the androgenic effect" 
Ecdysterone is a compound found in spinach and is there to protect itself against being eaten by caterpillars. When caterpillars eat the spinach they also consume the ecdysteriods, which helps to change them into butterflies. Interestingly butterflies tend not eat spinach due to its potent hormonal effect.
Ecdysteriods have been shown across a multitude of studies to be pro-anabolic , improve performance  and cause increased muscle growth,  but only in animal studies. One study in the Molecular Nutrition and Food Research looked at the effects ecdysterone had on muscle hypertrophy in rats. When researchers fed 5mg (50-100mg human equivalent) of ecdysterone daily for three weeks to see what affect it had on muscle size compared to a control group, their results showed that the daily dose of 5mg had a modest and noticeable affect on the rats' leg muscles.  This is thought to be down to the stimulatory effect ecdysteriods has on estrogen beta receptors, which have an anabolic effect in and of themselves, and also strengthen the anabolic effect of testosterone in muscle cells. They at least make sure that muscle cells produce more IGF-1 (insulin-like growth factor-1) when they receive anabolic stimuli from testosterone.  Nevertheless, despite numerous studies backing up the steroid-like affects ecdysteriods have there have been limited studies done on humans. To date there's only one showing that ecdysterone may be able to indirectly exert testosterone-like affects through a series of pathways.  Ultimately, this did not have any direct affects on the body's natural levels of testosterone . However, one study published in The American Journal of Clinical Nutrition did show signs to suggest Ecdysterone may be useful in muscle protein synthesis and gains in strength,  which may be the secret to how Popeye is able to lift 500lbs above his head: single handedly!
So the question remains, was Popeye right? Does Spinach increase strength and muscle mass?
Well, despite spinach being a nutritional superfood, containing a host of vitamins and minerals, more so vitamin A and magnesium than iron. Its somewhat steroid-like reputation may be a little over exaggerated from the results that current research suggests. By all means if you're a rat, a pig or even a sheep  ecdysteriod consumption from spinach would no doubt have some sort of an impact when it comes to muscle size and performance. However, for us humans I'm afraid that these steroid-like affects may just be a wishful thought…
Stay tuned for the second part when I'll be discussing the one other nutritional 'powerhouse' in spinach that most people are unaware of.
 Mahidol University, Thailnad
K. Sune Larsson in the Journal of Internal Medicine: The Spinach, Popeye, Iron, Decimal Error Myth is Finally Bustedhttp://www.bestthinking.com/articles/science/chemistry/biochemistry/the-spinach-popeye-iron-decimal-error-myth-is-finally-busted?tab=article
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 Gorelick-Feldman J, Cohick W, Raskin I. Ecdysteroids elicit a rapid Ca2+ flux leading to Akt activation and increased protein synthesis in skeletal muscle cells. Steroids. (2010)
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Parr MK, Zhao P, Haupt O, et al. Estrogen receptor beta is involved in skeletal muscle hypertrophy induced by the phytoecdysteroid ecdysterone. Mol Nutr Food Res. 2014;10. doi: 10.1002/mnfr.201300806.
 Velders M, Schleipen B, Fritzemeier KH, Zierau O, Diel P. Selective estrogen receptor-β activation stimulates skeletal muscle growth and regeneration. FASEB J. 2012;26(5):1909-20. doi: 10.1096/fj.11-194779.
 Báthori M, et al. Phytoecdysteroids and anabolic-androgenic steroids--structure and effects on humans. Curr Med Chem. (2008)
 Wilborn CD, et al. Effects of methoxyisoflavone, ecdysterone, and sulfo-polysaccharide supplementation on training adaptations in resistance-trained males. J Int Soc Sports Nutr. (2006)
 Bucci LR. Selected herbals and human exercise performance. Am J Clin Nutr. (2000)
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About Chris Hall
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