Five Health Myths Re-investigated
Do you really need to eat five daily portions of fruit and veg? Do you lose most hot from your head? Does reading in the dark wrecking your eyesight?
Eat five portions of fruit and veg a day
The five-a-day campaign has been running, in one form or another, in the UK since 1993. You may not know, however, that given this context, one section equals 80 g. What a nice, neat style, someone thought, of packaging the WHOs daily recommended fruit-and-veg dosage of 400g. But while the tagline has been taken into the nations bosom with people often jokingly wondering whether a Terrys Chocolate Orange, or glass of Fanta, counts as one of their five-a-day obesity has continued to rise, and fresh-produce consumption has declined .~ ATAGEND The cost of fresh food has risen, and lower-income households feed the least fruit and veg. Food pushers, meanwhile, cause mass embarrassment by flogging five-a-day items in random section sizes, and by only flagging up the five-a-day eligibility of more expensive, or less healthy, processed foods rather than basic, cheaper fresh ingredients.
As far as we know, though, the advice is actually sound. Some of the original hypotheses about the extent of the cancer protection that fruit and veg offers have been rubbished, but it is generally agreed that fruit and veg is nutritious, provides fibre, and takes up room on the plate that might otherwise accommodate adeep-fried Mars bar.( That said, “were not receiving” sorcery superfood, and other unprocessed foods are good for us, too .) In 2014, a study by University College London suggested that seven sections a day were necessary, but, soon after, a much larger study detected no evidence that more than five sections a day would devote further protection against some cancers and heart disease. Phew.
Drink eight glasses of water a day
No one knows where this dictum originated. A 1945 US Food and Nutrition Board document once said that we need 2.5 litres a day, but it also said that much of this can be obtained from food. In any case, how much we need fluctuates, on any devoted day, according to how active were being, what were feeing, whether were ill, and the climate. This is why our bodies handily tell us when we need more water( although old age can stymie thirst signals ). Dont listen to anyone who tells you youre already dehydrated when you feel thirsty. Person built that up.
In 2011, Margaret McCartney, aGP, wrote to the BMJ to highlight the lack of evidence for hydration advice, including the NHSs more modest recommendation of six to eight glasses( or 1.2 -1. 9 litres) a day. She namechecked an initiative called Hydration 4 Health, which promotes the added benefit of drinking extra water to the public and to doctors. Hydration 4 Health recommends two litres for men and a little less for women( 1.6 litres ). It is sponsored by the French company Danone, which owns Evian, Badoit and Volvic mineral waters.
A review study published in the Journal of the American Society of Nephrology in 2008 detected no clear evidence of benefit from drinking increased sums of water. The potential perks such studies investigated included improved kidney function and detoxification, clearer skin, fewer headaches and reduced calorie consumption due to feeling fuller. However, the authors wrote, although we wish we could demolish all of the urban myths found on the internet regarding the benefits of supplemental water ingestion, we confess i still have no clear evidence of lack of benefit.
You lose the most body heat from your head
Its easy not to topic this. Heat rises, after all. Roofs need insulation and so do heads. Except , now you mention it, so does any part of the body when it is cold. It is believed the embarrassment arose from the misinterpretation of an experiment carried out by the US military in the 1950 s. It was freezing and only the participants heads were exposed to the elements, so, of course, that is where they shed the most hot. More recent investigations have found that the head loses as much body heat as any other uncovered body portion. Bad news for the hat industry.
Starve a fever, feed a cold
This goes back a long, long way: it appears in John Withals dictionary of 1574, and has been linked to amisreading of Chaucerian English in The Canterbury Tales. The original reasoning was likely that fasting would cool the body during a fever, whereas feeing would warm you up when you have a cold. However, in practice, we should feed both colds and fevers. Fevers speed up the metabolism and burn more calories, sofoodis welcome. That said, if you lose your craving for a few days, bodies are adept at use fat stores for emergency energy. Drinking, however, is essential, and this is one occasion when you should force yourself to drink, even if you dont feel like it. Fevers and colds speed up dehydration( which will in turn cause mucus to harden, and this you really dont wantto happen ).
Reading in the dark ruins your eyesight
Poppycock. Reading in dim sun can be challenging, to the point of being deeply annoying. It can even give you a headache and result in tired or strained eyes. However, says the College of Optometrists, reading in dim sun or in the dark is highly unlikely to cause any permanent damage caused to your eyes. Some examines have found that myopia is more common in highly educated cultures, in which children grow up doing more close work, such as read, but the connection could simply be that richer populations have better access to diagnosis from eye specialists. Ideally, however, when reading after dark, sun should shine immediately on to the page, and not come from over your shoulder, thus causing glare.