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Can we in

uence the ecosystem of bacteria in our body with what we eat?

That’s the basic concept of probiotics. However, that concept is a bit

awed.

The primary conceptual problem here is that the ecosystem is easily altered.
In fact, it’s not easy to alter it at all. It’s very dif

cult for a new bacterial

species to work its way into that ecosystem.

Concepts aside, what does the evidence actually show? Do probiotic products
work for any speci

c indication? There are some indications for which a

mild bene

t has been shown for some probiotic products. However, that is

only the case when treatment is given very early and consists of probiotics
with high colony counts that contain several species.

Let’s talk about some speci

c uses. One use is preventing or treating

diarrhea resulting from antibiotics. It turns out if you have an infection

with

C. dif

cile

, the evidence

shows that probiotics are of no
bene

t. What about irritable

bowel syndrome, a very common
disorder? There is weak evidence
of a mild bene

t, but the best that

researchers could say at this time
is that more research is needed.
Probiotics have also been tested in

allergies. A 2008 systematic review of the evidence for a speci

c type of

allergy called atopic dermatitis found only mixed results. Do probiotics
work for

H. pylori

? There’s preliminary evidence for a mild bene

t, not

by itself, but as what we call adjunctive therapy. If you’re taking the other
treatments that have been shown to be effective for

H. pylori

and add

probiotics, you may have a mild advantage.

Most of the probiotic market is actually for routine use. Here I think the
evidence is pretty clear: If you’re a healthy individual with your normal
bacterial ecosystem, then eating speci

c types of live bacteria simply doesn’t

have any bene

t. It also should be noted that we are constantly exposed to

bacteria from our environment. Adding a few extra bacteria in a speci

yogurt doesn’t really add much to our environmental exposure to bacteria.
The bottom line is there is no evidence for routine use. While probiotics and

People tend to think of bacteria
as germs—things that cause
disease—when that is mostly
not true.

Lecture 6: Probiotics and Our Bacterial Friends

prebiotics are more hype than help currently, there is evidence that there may
be some potential symptomatic bene

t for speci

c medical conditions. We

may be able to affect human health with the probiotic approach, but we’re
not there yet.

Crislip, “Probiotics.”

Floch and Kim,

Probiotics.

What is the role of friendly bacteria in human health?

Are there any proven uses for probiotics?

Suggested Reading

Questions to Consider

Sugar and Hyperactivity

Lecture 7

In fact—and this seems somewhat counterintuitive—because caffeine is
a stimulant, it may improve attention and stimulate the frontal lobes to
function a little bit better. It may, paradoxically, decrease hyperactivity
or improve attention in children.

very parent knows that kids have a ton of energy, and hyperactivity
may just be a natural part of being young. But, in some children, it can
actually be a disorder, a disability that hampers school performance

and makes home life challenging. The search for a cause and a cure for
excessive hyperactivity in kids has led down many blind alleys. It has led to
an industry of self-help books leaving parents with a tremendous amount of
information, including a lot of misinformation.

One of the biggest hypotheses—and perhaps the biggest myth dealing with
childhood behavior—is the food hypothesis: Children behave the way they
do because of the food that they eat. This notion that there’s a link between
food and hyperactivity goes back to the 1920s and has been controversial ever
since. It was mostly popularized in the 1970s by Benjamin Feingold, who
created the Feingold diet. This is a diet that removes many things, including
food coloring, from children’s diets to eliminate or reduce hyperactivity.

A comprehensive review of the evidence performed in the 1980s showed
that there is no link between additives and food, and hyperactivity or
behavioral changes. But a recent study showed a weak correlation between
food coloring and parents noticing an increase in their child’s activity. It is
possible that there is a mild effect in a small subset, about 5%, of children.

There are also those who think that sugar is the culprit. Despite this common
belief with its obvious source in casual observations that most parents would
make, there is no link. There is no evidence to support a link between eating
lots of sugar and any behavioral change.

Lecture 7: Sugar and Hyperactivity

What about allergies? I’ve had parents tell me that they think that their child
has a food allergy, and that the allergic reaction is behavioral changes. Real
allergies cause skin rashes, breathing problems, sleeping dif

culty, and

generally feeling under the weather. Allergies do not cause hyperactivity or
other behavioral changes.

Attention de

cit hyperactivity disorder, or ADHD, is diagnosed in children

who are far enough to the hyperactive end of the spectrum that it begins
to impair their ability to function at home, at school, and in other
situations. ADHD is
best understood as a
relative de

ciency of

executive function in
the brain. Executive
function comes from
our frontal lobes,
which give us the
ability to look at the
big picture, to think
about the consequences
of our actions.

How do we diagnose
ADHD? There’s no
blood test. There’s no MRI scan. There’s no de

nitive objective biological

test to say who has ADHD and who doesn’t. With spectrums, there’s no
absolute objective place to draw the line. To meet the criteria for that
diagnosis, children or adults need to have at least 6 speci

c symptoms.

The symptoms need to be of at least 6 month’s duration and present in 2 or
more settings.

How common is ADHD? By the strict diagnostic criteria, about 3% to 8%
of children can be diagnosed with ADHD. About 50% of them will continue
to meet those criteria into adulthood. It is a bit of a myth that all children
with ADHD will outgrow their symptoms; only 50% do. A claim that
comes up frequently is that ADHD is overdiagnosed. I think it is important
that we do due diligence to make sure that we’re using our diagnostic

No link has been shown between eating sugar and
behavioral change.

criteria appropriately. This has been speci

cally studied. If ADHD were

overdiagnosed, you would expect that the false positive rate would exceed
the false negative rate. But in speci

c studies, they

nd that there’s no

difference. ADHD is actually not overdiagnosed, despite the very popular
belief that it is.

Is ADHD overtreated? There is an increase in the use of medication over
recent years, but studies have shown that this increase is mainly because
previously underserved populations are now being treated. A higher
percentage of people with ADHD are being treated.

While ADHD is a genuine disorder, it is also part of a spectrum of typical
childhood behavior and is highly treatable. We have very effective methods
of improving behavior and outcomes in children. There’s also a lot that
we’ve learned about what to do for your typical child who has the typical
range of hyperactivity—the kind of thing that all parents deal with.

There are a great number of myths out there about what triggers hyperactivity.
A lot of it revolves around food—sugar, caffeine, and food additives. These
serve as a distraction from the truth, and this is one of the big downsides of
myths. Misinformation is often more harmful than just ignorance. Parents
focus their efforts on highly restrictive diets that are very dif

cult and that

may cause more problems for their child. They are better off focusing on
basic parenting skills, forming a working relationship with their children,
and focusing on the behavioral modi

cation techniques that have been

effective for decades.

Hallowell and Ratey,

Driven to Distraction

MedlinePlus, “Hyperactivity and Sugar.”

Suggested Reading