1. Nearly every person on the surface
of the earth knows at least a little bit
about healthy and unhealthy habits
through parental guidance, word-of-
mouth, and “common knowledge.”
While these sources of information
are not the most reliable, they do
lead to globally accurate conclusions.
Meaning, people are usually aware
that eating too much can cause weight
gain, not brushing ones pearly whites
can result in cavities, and smoking
can increase the risk of lung cancer,
etc...But is every piece of health
information thrown around by the
majority necessarily true? You might
be surprised to find that some of the
most commonly adhered to and long-
lived pieces of advice are actually
completely false. It is time to debunk
them once and for all and honor those
which stay true to the facts.
left:akinbostanci/istockphoto;right:margarytavakhterova/istockphoto
Common Health Myths
DEBUNKED
by julia feygelman | designby catrina pang

2. why the belief is held
Many organizations have made this recommendation, including the
Institute of Medicine (IOM). The myth might be sourced back to a 1945
recommendation by the National Research Council, which once advised: “An
ordinary standard for diverse persons is 1 milliliter [of water] for each calorie
of food. Most of this quantity is contained in prepared foods,” but people
ignored the latter sentence, leading them to believe that they needed to
obtain the amount solely from drinks.
Another possible reason for this belief might be because of Frederick Stare
(MD, PhD), a highly regarded nutritionist and founder of the Department
of Nutrition at the Harvard School of Public Health, who said in 1974 that
people should consume “around 6 to 8 glasses per 24 hours,” with no
evidence to support his claim.
the verdict? false
According to a detailed 2002 review by the
American Journal of Physiology, rigorous evidence
for this belief seems to be lacking. The review,
which sought to find scientific studies supporting
the “8-by-8” (8 8-oz glasses) claim, found, on
the contrary, that studies following thousands of
adults assertively suggest that such a large intake
of water is not needed for healthy individuals.
The “8-by-8” recommendation is also exaggerated
because it disregards caffeinated drinks, juices
or sodas, and mild alcoholic beverages like beer
consumed in moderation as sources of hydration,
which newer studies count towards the daily total.
Following the American Journal of Physiology’s
investigation, numerous published experiments
stress the ability of the osmoregulatory system
(which maintains an organism’s internal balance
between water and solutes - components of
a solution or a substance dissolved in another
substance) to keep water balance in check. This
basically means that it is not vital to drink exactly
8 glasses per day because the body can regulate
its fluid concentrations as needed. It should be
noted, nonetheless, that large intakes of fluid can
be beneficial under special circumstances, such
as during strenuous exercise or in hot climates.
the real deal
TheIOM set anewstandard(in2010)of2.2liters(about
98-oz glasses)dailyforwomenand3liters(about12.5
8-oz glasses) formen,comingfromfoodandbeverage
combined, withabout19%comingfromfood.That comes
out to about 7 net glasses for women and 9.5 for men.
While these numbers are still close to the 8 8-oz glasses
recommendation, they have decreased from the IOM’s
2004 guidelines.
It is important to keep in mind, however, that due
to the body’s regulation responses, slight over- and
underhydration can be atoned for over the short term.
Thus, there is not one single water intake level that can
globally be labeled as the “healthiest amount” for sufficient
hydration.The new model represents an average, with the
precise amount varying from person to person. So how
does each individual figure out how much to consume?
The key for healthy people is to pay attention to thirst
signals as a guide to fluid requirements. According to
a 1965 study by the Journal of the American Medical
Association, these thirst signals include but are not limited
to: decreased skin turgor and a “full” (swollen) tongue.
Skin turgor can be self-determined by pinching the skin
on the back of the hand between 2 fingers for a few
seconds and then releasing it. Skin with decreased turgor
(a sign of dehydration) remains elevated and returns to its
original position more slowly. This, however, is a late sign in
dehydration. An easy and effective way to track hydration
level is by looking at urine color. According to a 2007
study by the Journal of the American College of Nutrition,
pale yellow urine indicates euhydration (normal level of
hydration), while darker yellow indicates dehydration.
Drinking 8 8-oz glasses of water per day
is necessary to stay adequately hydrated.#1

3. why the belief is held
Some people avoid eating foods such as eggs, shrimp, and
cheese because they contain high amounts of cholesterol,
making people believe that this will raise their blood LDL.
This belief emerged in the general population because there is
a myriad of controversial and contradicting information about
this issue in the media. Also, many overgeneralize the findings
by not differentiating between HDL (high-density lipoprotein,
or “good” cholesterol) and LDL, which skews the upshot.
the verdict? false
While ingesting dietary cholesterol can raise blood cholesterol,
there is a misconception about how and to what extent
this cholesterol contributes to the dangerous problem of
arteriosclerosis (thickening and hardening of the arteries)
that leads to CHD. When the artery is inflamed and damaged,
LDL tries to “patch it up,” and while this immune response is
initially helpful, it becomes dangerous when the inflammation
and LDL causes plaque buildup. Therefore, reducing dietary
cholesterol does not completely eliminate the cause of the
problem. The primary villains driving CHD are smoking, high
blood pressure, elevated blood sugar levels, alcohol, and
nutritional deficiencies, explains the New Zealand Journal of
Natural Medicine in a 2012 article.
According to a 2006 study performed by the Department
of Nutritional Sciences, University of Connecticut and
published in Current Opinion in Clinical Nutrition and Metabolic
Care, dietary cholesterol increases both “good” and “bad”
cholesterols, keeping the ratio at an innocuous level. The
former article agrees that the balance between the two is more
important than their individual values. Additionally, 70% of
the population experiences mild to no alterations in plasma
(i.e. contained in the blood) cholesterol when consuming high
amounts of dietary cholesterol (see our Q&A on eggs and
cholesterol from issue 2, volume 13, “Healthy Living from Head
to Toe” for the full scoop).
The conclusion? Healthy populations (i.e. not needing help
in daily activities and without serious conditions or diseases)
experience no risk in developing CHD by increasing cholesterol
ingestion. Also, itisoftenoverlookedthatsaturatedfat
raisesbloodcholesterolmorenotablythancholesterol
itself, as stated by a multi-authored article published by the
University of Illinois. Trans fats, according to 1990 study by The
New England Journal of Medicine, are even more detrimental
because they not only raise LDL, but also lower HDL. A 1995
study in The American Journal of Clinical Nutrition adds that
saturated fats are a more important elevator of LDL cholesterol
than unsaturated fats. It appears as though the majority of
studies on serum cholesterol point to fat as the culprit, not
dietary cholesterol.
right:stockcam/istockphoto;magone/istockphoto;juanmonino/istockphoto
Consuming foods that contain cholesterol raises blood
LDL (low-density lipoprotein, or “bad” cholesterol) and
increases the risk of coronary heart disease (CHD).
#2

4. eggs
Eating eggs may decrease the risk of developing macular degeneration (loss of vision) up to 40% due
to their carotenoid content, reports the Journal of the American College of Nutrition in 2000. Two large
eggs contain 0.3 mg of carotenoids. Because people’s sensitivity to dietary cholesterol is different
and depends on overall health, start with 1 egg or fewer per day for 3 months and have cholesterol
levels checked by getting a blood test. Based on these levels and your doctor’s recommendations,
the amount of eggs eaten can be decreased or increased.
According to a 2011 article by the University of Maryland Medical Center, sulfur (which is contained
in eggs) keeps joints healthy and may help in pain reduction. A 2002 study in Alternative Medicine
Review agrees and expands on this finding, reporting that sulfur may be efficacious in helping to
reduce the symptoms of arthritis and to treat allergies, pain syndromes, athletic injuries, and bladder
disorders.
Additionally, the Journal of Agricultural and Food Chemistry claimed in 2005 that eggs contain various
elements (such as lysozymes and oligosaccharides) that help protect against bacterial and microbial
infection.
shrimp
According to a 2010 study published in the Marine Pollution Bulletin and executed by the
Department of Marine Science at Coastal Carolina University, shrimp contains omega-3 fatty acids,
resulting in protective health effects such as reduced risk of cardiovascular disease, stroke, and
diabetes.
Stated in a 1996 article in the American Journal of Clinical Nutrition, shrimp consumption is also
deemed healthy for the circulatory system because its lack of saturated fat turns the tables on its
high cholesterol content and actually ameliorates the ratio of LDL (“bad” cholesterol) to HDL and
lowers blood lipid levels.
cheese
According to a 2009 article in Trends in Food Science and Technology, ingestion of probiotic cheese
(cheese made from raw, unpasteurized milk or aged cheese) has shown clinical benefits in its
ability to deliver viable probiotic bacteria into the human body. Probiotics, as defined in 2008 by
the International Scientific Association for Probiotics and Prebiotics and Dairy and Food Culture
Technologies, are “products that contain an adequate dose of live microbes that have been
documented in target-host studies to confer a health benefit.”
The former journal also found that probiotic cheese could decrease the risk of hyposalivation (dry
mouth, which can sometimes cause bad breath) and be advantageous for oral health in general.
the real deal
Foods containing relatively high levels of dietary cholesterol can have important health benefits.*
* While cholesterol-rich foods may possess benefits due to their other properties, they should still be consumed in moderation as
part of a balanced nutritional plan. The government’s “Dietary Guidelines for Americans” precautionarily advises to choose a diet low
in saturated fat and cholesterol, reports a 2011 article in Nutrition Reviews. According to a 1995 article in Circulation, there are indeed
clinical health benefits (such as lowering the incidence of CHD) related to lowering dietary cholesterol intake. A 2000 study in the
Cleveland Clinic Journal of Medicine confirmed that lowering cholesterol intake levels can, due to lowered blood LDL, reduce the risk
of developing CHD.
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5. Reading in dim lighting can damage eyes.
#3
why the belief is held
The concern that reading in dim light could diminish
eyesight might have originated in the feeling of eye
strain when trying to read in the dark. Inadequate lighting
can create the sense of having trouble focusing. It also
decreases the rate of blinking and leads to uncomfortable
dry eyes, especially when paired with squinting, say 2006
and 2005 articles in Insight and Optometry & Vision Science,
respectively.
the verdict? false
These sensations (straining, dry eyes) are not problematic
because the effects are only temporary. According to a
2003 patient handout, Taking care of your eyes: a collection
of patient education handouts used by America’s leading eye
doctors, reading in dim light does not lead to permanent
damage to eyes. There are temporary negative effects, but
the inherent functioning and structure of the eyes remain
unchanged.
the real deal
To adjust to lower illumination, the eye undergoes several
reversible changes. A 1996 treatise titled Biomembranes
reads that rhodopsin, a pigment in the retina (lining on the
inside of the eye receiving light) is the first to perceive light
and adapts immediately, while rods (photoreceptors in
the retina) are more sensitive to light and require longer to
adapt, reaching maximum sensitivity at around 30 minutes,
according to the 2008 edition of Psychology: The Science
of Mind and Behavior. Cones, photoreceptors responsible
for color vision, take about 9 to 10 minutes to adjust
(Encyclopedia Britannica). Luckily, the general consensus in
ophthalmology is that reading in dim light does not damage
nor hurt your eyes. The changes that occur during dark
adaptation can be accompanied by strain and temporary
discomfort, but are not damaging. The British Medical
Journal claimed in a 2007 article that hundreds of experts
agree that reading in low light does not harm your eyes.
left:ericferguson/istockphoto;kickstand/istockphoto;right:pixhook/istockphoto;
morepixels/istockphoto

6. You must wait 1 hour after eating before
swimming (or exercising).#4
why the belief is held
The idea behind this belief is that muscle cramping arises
(potentially leading to drowning if swimming) due to a lack
of oxygen-carrying blood to muscles which flows, instead,
towards the stomach to aid in digestion.
the verdict? true!
While it is best to wait several hours before exercising, it is
not for the reasons most people believe. While swimming or
exercising after eating is not life-threatening nor harmful in the
long run, it can still cause temporary yet significant discomforts.
In a 1992 study by the International Journal of Sport Nutrition,
all subjects who ate within 30 minutes of a triathlon vomited
while swimming. Those with vomiting symptoms had eaten
high-fat or high-protein meals. All individuals who experienced
intestinal cramps had consumed fiber-rich foods before the
race. American Association for Health, Physical Education and
Recreation had no complaints of stomach cramping with
swimming after eating in a 1968 study, but nausea did occur
when participants ate within 30 minutes of swimming, among
other minor physical disturbances with longer periods of time
between eating and swimming.
In the case of swimming, eating prior to the activity should
not cause serious adverse effects. According to Charles Smith,
MD, a board certified family physician at the Family and
Preventative Medicine Department at UAMS (University of
Arkansas for Medical Sciences), there is no medical evidence
supporting the drowning myth. The reality is that there is
enough oxygen to go around for both digestive purposes as
well as muscle function.
the real deal
According to a 2010 article published by Duke Medicine,
the biggest dangers entailed by eating and swimming
(or exercising) are most likely minor, non-life threatening
cramps and nausea. Elisabetta Politi, RD, nutrition director
at the Duke Diet & Fitness Center, mentions that the
best thing to do is to eat 2 to 3 hours before exercising
(to minimize possible discomfort). Eating right before
recreational swimming should not cause any issues, reports
the University of Arkansas for Medical Sciences.
summary
Health rumors will always continue to circulate whether due to the “telephone effect,” inconclusive
studies, or outdated die-hard recommendations. Now it’s 4 down, hundreds to go! The takeaway?
When it comes to staying hydrated, don’t drink until you feel like a water balloon to fulfill the 8-by-8
passé requirement. Instead, focus on the body’s signals or follow the simple instructions for detecting
dehydration. Craving a shrimp taco, grilled cheese, or tasty breakfast omelet? Go ahead and indulge,
in moderation. As long as the cheese is probiotic (such as cheddar, provolone, or gruyere), the melty
sandwich shouldn’t be a problem. After the tasty meal, swimming is on the agenda. Should one wait
for the hand to make the full 60 minutes? If not, minor cramps might be a consequence, so wait a
few hours to be on the safe side. However, there is no need to fear drowning if waiting isn’t an option.
In the evening, some reading sounds appealing. If it’s a little dark, temporary ocular discomfort may
occur, but don’t worry about permanent damage. tw