The five second rule: fact or fiction?

The five second rule: Fact or fiction?

With toddlers and young children constantly dropping food - then picking it up again to eat it - many parents want to know how careful they need to be about food hygiene for little kids - and whether there is any real science behind the 'Five Second Rule'.

What is the Five Second Rule?

Many people claim that the Five Second Rule applies to food dropped and quickly picked up again with the purpose of eating. The thinking is that it's OK to eat food that's been picked up in less than five seconds because it has not had enough time on the ground to collect germs and bacteria.

The science behind the Five Second Rule

In 2003, Jillian Clarke, a US student, conducted experiments investigating the validity of the Five Second Rule and discovered that bacteria can attach to objects much faster than five seconds. By covering ceramic tiles with the E. coli bacteria and using gummi bears (a sticky surface) and biscuits (a non-sticky surface) as the test foods, Clarke proved that food becomes immediately contaminated with bacteria on contact.

Testing of the Five Second Rule proved that:

Clean doesn't necessarily mean clean

Bacteria can live on all surfaces - a dirty floor, a cleaned bench-top, the cloth used to wipe the bench-top. While a floor that looks dirty is usually going to be worse than a floor that looks clean, it is all relative a clean floor will still house germs and bacteria.

Five seconds, thirty seconds, five minutes

The longer food spends on a contaminated surface, the more bacteria it will collect. Based on this finding, the Five Second Rule does apply - kind of. Food picked up in less than five seconds will have fewer bacteria on it than food picked up after five minutes BUT it will have been contaminated by bacteria in both circumstances.

Wet vs dry

How much bacteria contaminates dropped food is dependent on what type of food it is and what type of surface it is dropped on. Wet surfaces and wet foods will become contaminated faster than dry surfaces and dry foods. Having said that, food dropped in high traffic areas, like shopping centre floors, public toilets, footpaths, will become contaminated extremely quickly no matter what the food and no matter what the surface.

Does the Five Second Rule matter?

So with the Five Second Rule disproved, do we need to be on hyper-alert should kids want to eat food that has hit the floor? Yes and no.

Some bacteria are not harmful - but plenty are. And despite our best efforts to keep our homes clean, bacteria abound. Research has shown that some bacteria, such as salmonella (which causes food poisoning) can survive on surfaces for up to 28 days.

So while many bacteria on contaminated food won't do us any harm at all, some can make us incredibly sick - and as we can't see (or count) the number and type of bacteria on the food we eat, the rule of thumb for eating dropped food should generally be, if in doubt, throw it out.

Bacteria number-crunching

  • There are 49 germs per square inch on a toilet seat.
  • There are 7.2 billion germs on the average kitchen sponge.
  • There are 100 billion bacteria in our mouths.
  • There are 100 trillion bacteria in our gastrointestinal tracts.

Hygiene hypothesis

With the number of allergy sufferers on the increase in recent years, experts have developed a 'hygiene hypothesis' that questions whether our modern-day obsession with limiting our kids' exposure to bacteria in early life is having a detrimental effect on our children developing a robust immune system. Immunologists are now encouraging parents to let their kids run around outside, explore and get dirty. Part of this exposure includes the occasional consumption of bacteria on dropped food - following the Five Second Rule of course!



blog comments powered by Disqus

Nutritious first foods

  1. Apple and mango puree
  2. Apple and raspberry porridge
  3. Apple and raspberry puree
  4. Apple yoghurt
  5. Apple, pear and cinnamon puree
  6. Apricot chicken
  7. Baby bolognese
  8. Baby crispbread
  9. Baby guacomole
  10. Baby porridge
  11. Baby spaghetti bolognese
  12. Baby yoghurt
  13. Baby's first apple puree
  14. Baby's first vegetable purees
  15. Baby's rice pudding
  16. Baked custard
  17. Banana and avocado puree
  18. Banana oatmeal breakfast
  19. Banana pudding
  20. Banana teething biscuits
  21. Banana, raspberry and mango sorbet
  22. Bean, pea and potato puree
  23. Beef and vegetable dinner
  24. Beetroot and chickpea dip
  25. Beetroot and potato puree
  26. Blueberry, pear and raspberry swirl
  27. Boiled eggs
  28. Broccoli trees
  29. Broccoli, pear and pea puree
  30. Carrot and swede puree
  31. Carrot, corn and chicken
  32. Chicken and corn chowder
  33. Chicken, rice and vegetables
  34. Creamy sweet corn puree
  35. Delicious chicken dinner
  36. Easy beef casserole
  37. Easy chicken casserole
  38. Egg and vegetable omelette
  39. Eggless baby cereal cookies
  40. French toast soldiers
  41. Fruit jelly
  42. Fruit puree
  43. Fruity chicken and rice
  44. Homemade baby oat cereal
  45. Homemade brown rice cereal
  46. Homemade cheese sticks or cubes
  47. Homemade cottage cheese
  48. Homemade teething rusks
  49. Homemade yoghurt
  50. Hot corn cereal
  51. Lamb and pumpkin
  52. Nutritious teething biscuits
  53. Pea and zucchini puree
  54. Peach and mango mash
  55. Peachy chicken
  56. Pear and apricot puree
  57. Pear and rice puree
  58. Pear, peach and banana puree
  59. Penne pasta
  60. Pikelets
  61. Pumpkin and potato mash
  62. Pumpkin and spinach risotto
  63. Red egg
  64. Rice and lentil dinner
  65. Roasted pumpkin puree
  66. Steamed and julienned carrot sticks
  67. Stewed prunes
  68. Sweet corn and avocado puree
  69. Sweet potato and sweet corn mash
  70. Sweet veggie puree
  71. Weet-Bix custard
  72. Weet-Bix with apple and cinnamon
  73. Zucchini, potato and spinach mash