foods elicit such strong opinions as milk and dairy products.
People don't simply like milk, or avoid milk, they preach
about its virtues or its evils. The cow's-milk-is-for-calves
folk warn that dairy is behind nearly all our major diseases,
from cancer and diabetes to heart disease and even osteoporosis.
Meanwhile, the other side would have you believe that dairy
is essential, that your bones will crumble if you don't
drink milk, and that it will prevent hypertension and even
promote weight loss.
used to be considered a perfect food, and nearly everyone
agrees it's very nutritious and by far the leading source
of calcium in the diet. Thus, last year's new federal dietary
guidelines specified three cups of low-fat or non-fat milk
or other dairy products every day (two cups for kids age two
to eight)or else calcium-fortified foods and beverages. This
caused an uproar among anti-milk groups, and even some mainstream
nutrition experts suspected that the strong influence of the
dairy industry played a role.
has been lots of research about dairy in recent years, so
it's time for an update. Here are the main issues.
or bad for your heart?
you consume lots of whole milk and cheese, you're likely
to see your blood cholesterol levels rise. That's true,
however, of any foods rich in saturated fat. But more and
more dairy products these days are nonfat or low-fat, and
thus do not raise cholesterol levels. In fact, there's
some evidence that certain substances in milk may help lower
opponents often cite a few studies that indicted milk (sometimes
even nonfat milk) as a cause of heart disease. But these studies
are not convincing, and many others find no increased coronary
risk or even show reduced risk. Moreover, since dairy is rich
in calcium, potassium, and magnesium, it can help reduce the
risk of hypertension, and thus it is an important part of
the DASH diet.
opponents often claim that dairy products increase the risk
of breast, prostate, and ovarian cancer. Some studies have
linked high intakes of calcium and/or dairy to increased risk.
But others have found no connection, and even a reduced risk.
In 2004, for instance, a review of 46 studies on dairy consumption
and breast cancer found no clear link negative or positiveto
breast cancer. There is, however, fairly good evidence that
dairy products help reduce the risk of colon cancer. One complication:
dairy products contain many nutrients, some of which may decrease
the risk of certain cancers (such as vitamin D), while other
may increase it (such as fat or milk sugar).
decade ago a group of anti-milk physicians, including the
late Dr. Benjamin Spock, shocked parents by claiming that
dairy products increase the risk of Type 1 (previously called
juvenile) diabetes. This has never been proven, though breast-fed
children do seem to have a lower risk of the disease. No reputable
authorities have proposed that children avoid milk and dairy
products. As for adults, dairy may reduce the risk of Type
2 diabetes. Last year, for instance, Harvard researchers linked
increased dairy (especially low-fat) with a lower risk in
may have thought that this at least was certain that getting
calcium from dairy products throughout your life is the key
to keeping bones strong and thus preventing osteoporosis.
In fact, the calcium/bone story is very complicated. Some
studies have found that consuming dairy or calcium leads to
greater bone density, but others have not. So many factors
affect bone health from genetics, physical activity, and body
size to age at menopause and a wide array of nutrients that
it's hard to tease out dairy's effect. Consuming adequate
calcium is important, especially from childhood through early
adulthood. However, once an older adult has weak bones, increasing
calcium intake by itself has minimal effect.
anti-milk groups claim that dairy products actually increase
the risk of osteoporosis. They point to the fact that in countries
such as China and India, where dairy products are rarely consumed
and calcium comes primarily from green vegetables, the rate
of osteoporosis and fractures is much lower than in the U.S.,
where dairy consumption is high. But it's not possible
to blame these national differences in bone health solely
on dairy intake, since genetic, cultural, and lifestyle factors,
as well as other dietary ones, undoubtedly also come into
possible problem with dairy products is that they are rich
in protein and a high protein intake slightly increases calcium
excretion in urine and may reduce bone density. However, adequate
protein helps keep bones strong, and the high levels of calcium
in dairy products may more than offset the small adverse effect
their protein has on bones. In addition, milk is almost always
fortified with vitamin D, which is as important for bone health
as calcium, according to recent research.
the grand scheme of factors affecting bone health, dairy and
calcium intake after early adulthood is likely to play a small
beneficial role. Don't believe claims that dairy products
hurt your bones.
latest argument about dairy is whether it helps people lose
weight, or at least prevents weight gain. The dairy industry
has advertised this virtue, based largely on studies it has
funded. However, not all studies have linked dairy or calcium
to weight loss. Even the positive studies found only a small
benefit over long periods. The key to weight control is, as
always, consuming fewer calories than you burn. Calcium by
itself will not make you lose weight. But if you are trying
to lose weight, don't drop dairy foods from your daily fare.
Just choose low-fat or nonfat products. They may help a little.
people are anti-milk because they think milk is anti-them
that is, it causes bloating and diarrhea, symptoms of lactose
intolerance. Most Asian and African adults, as well as Native
Americans, Latinos, and Ashkenazi Jews, have trouble digesting
milk because they have lower levels of lactase (the intestinal
enzyme that digests milk sugar, or lactose) than people of
northern European descent. Still, many studies have shown
that lactose intolerance is less prevalent than is commonly
believed. Also, even those who truly are lactose-intolerant
are often able to digest a cup or two of milk a day, if consumed
at meals, with few if any symptoms. Lactose intolerance is
not an all-or-nothing scenario, but a matter of degree. In
one study, black Americans who were on the DASH diet were
able to eat three servings of dairy products daily without
any adverse effects.
and low-fat dairy products are good foods, but like other
good foods, you don't have to consume them if you don't
like them or they don't like you. While for most people
a balanced diet featuring all major food groups is the best
way to get the nutrients they need, a diet lacking a food
group can be healthy too, though it may take a little extra
planning. For instance, vegetarians, including those who avoid
dairy, have a lower risk for many chronic diseases.
most people, dairy is an easy way to get calcium and other
important vitamins and minerals. Some green vegetables (such
as collards and broccoli), salmon or sardines (with the bones),
soybeans, and almonds are also fair-to-good sources of calcium,
though most of us don't eat lots of these foods. Calcium-fortified
foods, such as orange juice, soy milk, and breakfast cereals,
are good options. And calcium supplements can easily make
up for calcium missing from your diet. The 2005 federal guidelines
strongly emphasized dairy largely because its potassium helps
prevent hypertension. But, again, you can get potassium from
other foods, especially produce.
your diet is good (lots of fruits, vegetables, and whole grains,
plus small portions of lean protein), consuming little or
no dairy won't be a problem, as long as you make sure you
get adequate vitamin D, calcium, and potassium from other
sources. If you are over 50 and don't drink milk, you almost
certainly need to take vitamin D supplements to get 400 IU
a day (that's the amount in most multivitamin/mineral pills).
If you are over 70, even if you do drink lots of milk, you'll
need supplemental D to reach the 800 to 1,000 IU a day.