Dairy products include a variety of
nutrient-rich foods and beverages that are made from or contain milk.
Milk and dairy products are considered nutrient-rich foods. This
is why some health authorities, such as the United States Department of
Agriculture (USDA), recommend consuming dairy products daily (1).
However,
the scientific evidence on whether dairy products are healthy or harmful is
mixed – and there are complexities behind these labels.
More
than half of the world's population reports having difficulty digesting dairy
products, and you may be wondering if you should continue to consume it (2).
This
article delves into dairy products and explores how it affects your health.
What is
dairy products?
Dairy
products are foods made from or contain dairy products from mammalian milk,
such as cattle, sheep, goats or buffalo.
This
group includes foods such as regular and lactose-free milk, yogurt, cheese and
kefir, as well as milk-containing products such as ice cream, butter, ghee,
cream, cream cheese, whey products and casein (3).
As you
can imagine, dairy products are produced through different techniques and
processing methods, which help to improve the quality they require.
For
example, liquid milk can be processed into semi-skimmed, skimmed, evaporated,
or milk powder, where some or all of the fat or water is removed to produce a low
fat, concentrated, or dried form of milk (3).
In addition, vitamins
and minerals can be added instead of removed, as in the case of fortified milk.
(3)
Given
its short shelf life, milk is usually pasteurized, a type of heat treatment
that reduces the number of harmful microorganisms that can damage the milk or
pose a health hazard to consumers.
Other products, such as
cheese, are produced by coagulation of casein, one of the main proteins of
milk, as well as whey separated from milk. (3)
In
contrast, fermented products such as yogurt and kefir are produced by adding
beneficial bacteria to increase the acidity of milk (3).
Summary: dairy
products are foods made from or contain dairy products from mammals' milk. Some
popular dairy products include milk, yogurt, kefir, ghee, butter, cream, cheese
and whey.
Nutritional
content of dairy products
As
mentioned earlier, milk and dairy products are nutrient-rich foods with many
nutritional advantages. In fact, milk contains 18 of the 22 essential
nutrients, including vitamins, minerals, probiotics, and antioxidants (4, 5, 6).
1-cup
(244 ml) whole milk package (7):
- calories: 146
- protein: 8 g
- fat: 8 g
- carbohydrates: 11 g
- Vitamin B12: 55% of
daily value (DV)
- calcium: 23% of DV
- phosphorus: 20% of DV
- Vitamin D: 13% of DV
- potassium: 8% of DV
It also
provides significant amounts of vitamin a, selenium, zinc and magnesium.
Based
on its nutrient content, whole milk is very healthy. Just 1 cup (244 ml)
provides all 3 macronutrients – carbohydrates, proteins and fats.
The fat
composition of milk depends on the diet and treatment of the animal from which
it originated. Milk fat is very complex and contains hundreds of fatty acids. Many
are biologically active, which means they are beneficial to your body (8).
For
example, studies have shown that pasture-raised grass-fed cows may contain 92%
more omega-3 fatty acids and conjugated linoleic acid (CLA) in their milk than
conventionally raised cows. （9, 10)。
Keep in
mind that high-fat dairy products, such as some cheese and ice cream and
fortified soy products have a very different nutritional content than milk. In
addition, low fat or nonfat dairy products lack most or all of the healthy fats
of milk.
Another
important nutrient in dairy products is lactose, which is the main carbohydrate
found in the milk of all mammals. Milk from ruminants (animals such as cattle
and sheep) contains about 5% lactose (2, 5).
The
main role of lactose in milk is to provide energy. It also has a potential
prebiotic effect, which means it can promote the growth of beneficial bacteria
in your gut, allowing you to have a healthier bacterial community (2, 5).
Summary: milk is
nutrient-rich and its composition may be influenced by the diet and treatment
style of the animals from which it originated. However, it varies depending on
the product. For example, whole milk provides more healthy fat than skim milk.
The
health benefits of consuming dairy products
Can
support your bones
Calcium is the main mineral in bones—dairy products are the best
source of calcium in the human diet (11, 12).
Therefore,
dairy products have many benefits for bone health.
In
fact, healthy organizations recommend that you consume 2-3 servings of dairy
products per day to get enough calcium to maintain bones (1, 13).
There
is evidence that dairy products can improve bone density, reduce the risk of
osteoporosis, and reduce the risk of fractures in older adults (12, 14, 15).
That
said, dairy products are not the only dietary source of calcium. Non-dairy
sources of calcium include kale, leafy greens, legumes, and calcium supplements
(12).
However,
studies have shown that calcium is not the only nutrient that dairy products
have on bone health. Dairy products also provide protein and phosphorus, which
you need to reach optimal peak bone mass during bone growth and prevent bone
loss as we age (12, 15).
May reduce your risk of
obesity and type 2 diabetes
Dairy
products are associated with different effects on body weight.
There
is evidence that dairy products can improve body composition by reducing fat
mass, waist circumference, and increasing lean body mass, especially when
combined with a low-calorie diet (12, 16, 17).
a
review of 25 studies found that various types of yogurt—including traditional,
low-fat, high-fat, and Greek yogurt—were associated with risk factors for
preventing metabolic syndrome, such as obesity, hypertension, hyperglycemia,
and triglyceride levels (18).
Some
evidence also suggests that some dairy products may reduce your risk of
developing diabetes. However, studies have shown mixed results (6, 19).
studies
have found that while yogurt may reduce the risk of developing type 2 diabetes,
the association between other dairy products and diabetes risk is not
consistent (6, 19, 20, 21).
One
possible explanation for the effects of yogurt on diabetes risk is related to
its nutritional content.
For
example, calcium and magnesium are associated with a lower frequency of insulin
resistance, while whey protein has hypoglycemic properties due to its positive
effect on insulin production. （19）。
In
addition, the probiotics in yogurt play a key role in controlling blood sugar
levels through mechanisms involving multiple organs and systems from the brain
to the immune system and gut. （22）。
Dairy
products and heart disease
Current
dietary guidelines recommend choosing low-fat dairy products to limit saturated
fat intake and reduce the risk of heart disease (13).
However,
recent evidence suggests that saturated fats in dairy products may have
different adverse effects on heart health than saturated fats in meat. That is
because dairy and meat have different fatty acid compositions (12, 16, 23).
Unlike
meat, which contains long-chain fatty acids, dairy products contain a greater
proportion of short- and medium-chain fatty acids. Short- and medium-chain
fatty acids have different effects on heart health and may even bring some
benefits (16, 23, 24).
Fermented
products such as yogurt and kefir provide probiotics, which are wholesome
microorganisms. Studies have shown that their intake has been linked to lower LDL
(bad) cholesterol levels and a lower risk of high blood pressure and heart
disease (23).
However,
there is no consistent evidence that creams contribute to or hinder heart
health, and the scientific community disagrees.
Summary: dairy
products may benefit your bones, reduce your risk of type 2 diabetes, and
improve your body composition. Although the evidence is inconclusive, they may
also improve heart health.
Potential
drawbacks of consuming dairy products
Lactose
intolerance
As
mentioned earlier, the main carbohydrate in dairy products is lactose, a milk
sugar composed of two monosaccharides, glucose and galactose.
To
digest lactose, children produce a digestive enzyme called lactase, which
breaks down the lactose in breast milk. However, many people lose the ability
to break down lactose in adulthood (2, 25).
In
fact, approximately 65% of the world's adults are unable to break down lactose,
leading to lactose intolerance (2).
What's
more, only a small percentage of people – especially those of Nordic ancestry –
are known to have lactase persistence, which means they can still produce
lactase. This ability may stem from the evolutionary adaptation of cow
domestication (2, 25).
People
with lactose intolerance experience digestive symptoms when consuming dairy
products. These symptoms may include flatulence, bloating, abdominal cramps,
and diarrhea (2, 26).
Current
treatments for lactose intolerance include lactose reduction diets and enzyme
replacement therapies (25, 26).
However,
some people with lactose intolerance may still be able to tolerate 9-12 grams
of lactose per day – equivalent to about 1 cup of milk (200 ml) – and a small
amount of fermented product (2).
Dairy
products and cancer
Dairy
products stimulate the release of the protein insulin-like growth factor 1
(IGF-1), which is associated with an increased risk of certain cancers, notably
prostate, breast, and colorectal cancers. （27, 28）。
However,
research on the link between dairy and cancer remains inconclusive, and there
is evidence that the type of dairy products consumed may play an important role
in the outcome. （29）。
For
example, a study of 778,929 people showed that while total dairy products did
not increase the risk of cancer death, whole milk intake did increase the risk
of prostate cancer death. （30）。
Conversely,
yogurt and other fermented dairy products have been linked to a reduced risk of
cancer (31).
The
impact of the dairy industry on our environment
The
dairy industry is one of the biggest contributors to climate change and
food-related.
In
fact, dairy products come in second place when it comes to producing dietary
greenhouse gas emissions (GHGE) – after meat. Dairy products are estimated to
account for about 20% of global food production emissions (32, 33).
Greenhouse
gases – including methane, nitrous oxide and carbon dioxide – are among the
biggest contributors to climate change because of their ability to contribute
to global warming (32).
As a
result, studies have shown that replacing dairy products with plant-based alternatives
can significantly reduce GHGE (33).
However,
following a diet rich in plant-based foods may make it difficult for you to
meet your dietary mineral needs, such as calcium and vitamin D requirements (34).
A
well-planned diet and supplements can help. If you are interested in
drastically reducing your dairy intake or switching to a plant-based diet, it
is best to talk to a medical professional such as a doctor or dietitian first
to make sure you are getting all the nutrients you need.
Summary: more
than half of the world's adults may have difficulty digesting dairy products. In
addition, while some dairy products appear to increase the risk of cancer,
others may lower it. However, the evidence is mixed. Finally, the dairy
industry is one of the biggest contributors to climate change.
The
best dairy products for your health
The
healthiest and greenest dairy products come from grass-fed and/or
pasture-raised cows.
As
mentioned above, their milk has a better nutritional content, including a more
beneficial fatty acid composition.
Fermented
dairy products such as yogurt and kefir may be better because they provide
probiotics, and studies have consistently linked them to a lower risk of type 2
diabetes, heart disease, and cancer. （19, 22, 31）。
It is
also worth noting that people who cannot tolerate dairy products may easily
digest goat milk products (35).
Summary: the
best types of dairy products come from grazing and/or grass-fed animals because
their milk is richer in nutrients. Fermented products are also consistently
associated with many health benefits.
Bottom line
Dairy
products include a variety of nutrient-rich foods and beverages that are made
from or contain milk.
In most
cases, they are associated with many health benefits. However, the evidence
remains inconclusive as to their benefits and potential drawbacks.
In
addition, most people become lactose intolerant and at some point cannot tolerate
dairy products.
If you
can tolerate dairy products and enjoy them, you should feel comfortable eating
them.
If you do
not tolerate them well, do not like them, or have ethical concerns about the
impact of agricultural practices or dairy production on the planet, there are
plenty of dairy alternatives and they may be available to you.