Why does good so often triumph over evil? How is it that, in the world's great fantasy stories, sorely outmatched heroes and heroines surmount the odds to trump the forces of darkness? Is it the power of love? A stout heart and the bond of friendship? A manifestation of greater cosmic justice? Writing for the Medical Journal of Australia, Joseph Hopkinson and his father, Dr. Nicholas Hopkinson, offer up a less romantic answer: it's nutrient deficiency.

From cave-dwelling Gollum to Smaug, holed up in the Lonely Mountain, to the forces of Sauron, living in the dark, defiled land of Mordor, the evil denizens of Middle Earth—the focus of the Hopkinsons' analysis—all suffer a consistent problem: their diets, short in fresh fruits and vegetables, and their affinity for dark places, leaves them deficient in vitamin D.

Vitamin D supports calcium metabolism, and having a shortage of the vitamin, says the study, can cause rickets and other bone problems.

Vitamin D also has immune-modulating roles with potential effects on susceptibility to conditions ranging from multiple sclerosis to tuberculosis and accelerated lung function decline.

So, when push comes to shove a veteran goblin may be bested by a fresh-faced hobbit not because of the halfling's prowess in battle, but by the goblin's advanced musculoskeletal decay.

The Hopkinsons' write that “[m]ore research would be needed to establish whether the results of the current pilot investigation are representative of the wider Tolkien corpus and indeed of fantastic literature in general,” but we could see the hypothesis making sense. After all, how many super-villains lodge in hollowed-out volcano lairs or deep-sea bases, totally deprived of regular access to sunlight?

Then again, published as a “Christmas cracker” in a special Christmas edition of the medical journal, the Hopkinsons' analysis was obviously not ushered through the typically rigorous peer review process, otherwise they would have realized that their hypothesis totally fails to account for good guy cave-dweller Batman. (Though, as a modern multibillionaire, maybe Bruce Wayne takes vitamin D supplements.)

H/T Science Magazine

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