Will eating spinach make me strong?

Also in this week's column:

• Do you feed a cold and starve a fever?
• What fluids should you drink when it's hot?
• What is amniotic fluid?

Will eating spinach make me strong?

Asked by Thomas Glass of Hartford, Connecticut, USA

The Popeye Effect is the belief that eating spinach will give you big muscles. Unfortunately, this is a myth.

Just eating spinach is not going to make anyone as strong as the cartoon character, Popeye. If it did, body-builders and athletes would be popping tins of spinach as often as Popeye did in his cartoons. Come to think of it, Bluto would be eating spinach too!

The fact is that many other nutritional supplements build muscle bulk and strength faster and more effectively than spinach. However, it is often true that people with weak muscles have a variety of vitamin and mineral deficiencies.

"Spinach" derives from the Latin word spina meaning "spine". Spinach is a vegetarian, low-calorie, non-animal source of iron and magnesium. Both are essential to muscle development. Spinach also contains vitamin C, vitamin B-9 (folate, folic acid), and additional antioxidants that the conventional wisdom in human nutrition claims helps prevent cancer. All of these are beneficial to the body.

Dr Shawn Somerset of the School of Public Health at Griffith University in Brisbane, Australia, points out that a difficulty in over-relying upon spinach as a source of iron is that spinach is rather poorly absorbed by the body unless eaten with calcium. The type of iron found in spinach is non-blood (non-heme), a plant iron, which the body does not absorb as efficiently as blood (heme) iron, found in meat.

The myth of the Popeye Effect dates back to a real scientific mistake. In 1870, Dr E von Wolf mistakenly misplaced a decimal point and wrongly estimated the iron content of spinach to be 10 times more than any other green vegetable. The mistake was corrected only in 1937. But by then it was too late. The first Popeye cartoons appeared in 1929 - and the spinach-muscles-strength legend was already born.

Health benefits of spinach

The idea that spinach makes you strong relates to its iron content. Iron is essential for transporting oxygen from the lungs to the muscles and for storing oxygen in the muscles.

Health benefits of spinach include:

• Protecting against heart disease
• Helping prevent colon and prostate cancer
• Maintaining good eye health
• Reducing chances of brain damage after a stroke
• Helping preserve healthy bones

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au