There are lots of facts and myths about skim milk.
While some people claim it is lower in "harmful" saturated fat, others feel that dairy fat is perfectly healthy.
People have a few valid concerns about skim milk too.
Is it really healthier or is it better to stick to whole milk?
This article takes a balanced look at the nutrition profile, health benefits, concerns and recent studies on skim milk.
What Is Skim Milk?
Skim milk is simply milk that has had the butterfat removed.
We will examine the full nutritional content a little later on, but it usually has between 0% and 0.1% fat content.
Depending on where you live, you may know this type of milk by different names;
It is also common to hear people call it 'non-fat' or 'fat-free' milk.
The main difference in the nutrition profile of whole and skim milk is the calories and fat content.
As skim milk contains no fat, the total amount of calories (1 gram of fat = 9 kcal) is much lower.
How is Skim Milk Made?
To make skim milk, producers use a centrifugal separator, which is a machine that removes the fat globules from the milk.
Centrifugal separators operate by spinning the milk at extremely high forces.
During this process, the milk and the fat separate and run off into two different spouts which lead to containers within the centrifuge, ready for collection.
Key Point: Skim milk contains almost no fat and it is much lower in calories.
Skim Milk's History
Interestingly, skim milk started life as a "fattening" supplement for pigs.
Farmers added it to grain-based pig feed to make the food more palatable and to encourage the swine to eat more (1).
Over the past few decades, skim milk became a desirable alternative to whole milk as consumers sought low-fat options.
The US Department of Agriculture (USDA) played a big part in this when they introduced low-fat dietary guidelines in 1980.
Following this, whole milk consumption began to fall at the expense of low-fat options.
The rise in skim milk gathered pace when the USDA then recommended the population switch to low-fat dairy for the first time in 1985 (2).
However, in recent times the fear of dietary fat is slowly subsiding and skim milk sales have begun to fall.
This interesting chart shows how milk sales have changed over the past few decades (3);
Key Point: Skim milk was initially used for fattening pigs rather than for human consumption. However, it became popular as the low-fat trend took off.
Aside from a lower fat and calorie content, skim milk has a similar nutritional profile to whole milk.
Here are the nutritional values per 100 g (4);
Skim milk contains around 5 grams of carbohydrate per 100 ml and this comes in the form of the milk sugar lactose.
Regarding protein, skim milk offers a 'complete' source.
In other words; it contains the full range of essential amino acids like all animal products do.
The amount of fat is negligible and ranges from 0 g to 0.1 g.
Amount (% RDA)
The vitamin profile of skim milk is similar to regular milk.
However, there is one key difference;
Skim milk is fortified with synthetic vitamin D, which is mandated. It may also be fortified with vitamin A, but this is not a mandatory requirement.
This vitamin fortification is because milk loses its natural fat-soluble vitamin content when the fat is removed.
In contrast, whole milk contains all its original fat-soluble vitamins.
Amount (% RDA)
As shown in the table, skim milk is an excellent source of dietary calcium and it provides a decent amount of several minerals.
Key Point: Skim milk provides a similar nutrient profile to whole milk and it is particularly high in the mineral calcium. It also provides an excellent source of complete protein.
What Health Benefits Does Skim Milk Have?
There are two main benefits of skim milk; protein and the calcium content.
Of course, all milk is a good source of calcium and so this isn't a unique point, but skim milk does have the best protein density.
Since it is much lower in total calories, skim milk has a much higher protein density than other milk options.
For instance, 100 grams of skim milk contains 34 calories and 3.4 grams of protein.
One gram of protein is equal to 4 calories, so there is a total of 13.6 calories from protein per 100 grams.
These ratios give a protein density of 40%.
In contrast, whole milk contains the same amount of protein, but the same serving size provides around 60 calories of energy.
As a result, whole milk has a protein density of only 22.7%.
With this in mind, skim milk is the better option if someone is looking to increase their protein intake without a lot of excessive calories.
Key Point: Skim milk is very protein-dense compared to other milk choices.
Just like whole milk, cheese and all dairy foods, skim milk contains a high amount of calcium.
Firstly, it is important to ensure we consume enough calcium since it has a range of essential roles within our body.
Some of the mineral's benefits include;
Key Point: Skim milk is rich in protein and more protein-dense than other types of milk. It also offers a rich source of calcium.
Concerns About Skim Milk
While skim milk has a couple of benefits, there are a few disadvantages too.
These include the loss of natural fat-soluble vitamins, higher sugar density, and yes.... the taste.
1. Fat-Soluble Vitamins
Whole milk contains a range of naturally occurring fat-soluble vitamins and these include;
There is just one problem; all these vitamins are fat-soluble.
This being the case, when skim milk has its fat removed, it also loses the majority of these vitamins.
Manufacturers must (by law) fortify skim milk with synthetic vitamin D to make up for this loss. Additionally, some producers may also fortify their milk with vitamin A - it is their choice.
However, many do not.
Non-fortified milk will, therefore, have significantly less vitamin A content than whole milk, and it will also lack the small quantities of vitamins E and K (10).
Typical Vitamin A Content
A recent study analyzed 30 paired samples of whole milk and skim milk to test their vitamin A contribution toward the RDA (11).
On average, the skim milk in this study contributed 1.3% of the RDA for vitamin A per 244 ml serving.
In contrast, whole milk offered a 7.6% contribution - almost 600% more vitamin A per serving.
Can We Absorb Vitamin A In Skim Milk?
There are also some concerns that we may not be able to absorb (fat-soluble) vitamin A in fat-free skim milk.
However, these claims do not appear to be supported by science.
For instance, one controlled study compared the bio-availability of whole milk and vitamin A-fortified skim milk (12).
In this study, 19 volunteers consumed 430 ml of each milk on different days and researchers took their plasma (blood) levels of vitamin A for 6.5 hours after the drink.
The results showed no relative difference in the absorption level of vitamin A between each drink.
Key Point: On average, whole milk has a better vitamin profile than skim milk. Additionally, the concentration and relative ratios of all vitamins exist in the amounts found in nature.
2. Sugar Density
Skim milk contains the same amount of lactose as whole milk. However, it contributes a much higher percentage of total energy.
Earlier, we looked at how skim milk is more protein-dense than whole milk due to the lower calorie count.
This works both ways.
Skim milk also has a much higher milk sugar (lactose) density than whole milk does.
While whole milk provides approximately 33% of calories from sugar, this figure rises to 57% in skim milk.
Could This Cause Any Negative Effects?
Is it possible that the higher sugar density could cause problems?
One theory thrown around is that the lactose could have a more significant impact on postprandial (after consumption) blood-glucose levels.
This idea revolves around the lack of dairy fat that would otherwise slow digestion.
However, according to recent studies, this doesn't appear to be the case.
A study conducted by Loren Cordain, among others, showed that there were no significant differences between skim and whole milk consumption on glycemic and insulinemic response (13).
Another recent controlled trial also compared the glycemic and insulinemic responses of various milk beverages consumed alongside a pizza (!) breakfast meal (14).
However, again, there were no differences between skim and whole milk.
Key Point: Skim milk has a much higher sugar-density than whole milk, but it doesn't appear to cause a higher glycemic response.
3. Skim Milk Doesn't Contain Saturated Fat
As you may be aware, saturated fat has been unfairly demonized for decades and it is only recently recovering.
While some people still scaremonger about saturated fat, butter sales are back up and people have stopped trimming the fat off their meat.
The reason why is because much of the "harmful" claims about this type of fat were greatly exaggerated.
While binging on the stuff won't support optimal health, there is nothing wrong with naturally occurring saturated fats in food.
Think of food as food and not as isolated ingredients.
In fact, saturated fatty acids play a range of beneficial roles in our body. Here are a few of the systems in which they are involved;
Skim milk removes the (saturated) dairy fat, yet it is a perfectly healthful fat that provides benefits.
Key Point: Skim milk doesn't contain saturated fatty acids. Despite fear-mongering in the media, saturated fat has beneficial effects.
4. The Taste
Skim milk just doesn't taste very good... there isn't much else to say.
Is Skim Milk Healthier Than Whole Milk?
As we have seen, the truth about skim milk's nutritional profile isn't quite as good as some people say.
On the other hand, it also isn't as bad as others claim.
The big question; how does it compare to whole milk in studies on human health?
Studies Comparing Skim Milk and Whole Milk
To answer this question, we will examine some of the recent studies that directly compare the two.
These papers are all systematic reviews and large-scale cohort studies conducted within the last five years.
1. Comprehensive Review of the Impact of Dairy Foods and Dairy Fat on Cardiometabolic Risk (2016)
This particular systematic review compared nine randomized controlled trials on dairy fat.
Findings included (18);
Key Point: There were no negatives from either skim or whole milk. However, dairy fat may have more long-term benefits related to type 2 diabetes prevention.
2. Dairy products and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of cohort studies (2013)
This dose-response meta-analysis examined seventeen cohort studies looking into dairy foods and type 2 diabetes risk.
Findings included (19);
Key Point: This systematic review found that both skim and whole milk consumption correlates with reduced type 2 diabetes incidence.
3. Biomarkers of Dairy Fatty Acids and Risk of Cardiovascular Disease in the Multi-Ethnic Study of Atherosclerosis (2013)
This cohort study featuring 2837 US adults examined the impact of different dairy products on cardiovascular risk.
The main results were as follows (20);
Although this study favors whole milk over skim milk, the researchers made an interesting observation.
What if dairy fat intake is associated with other factors related to cardiovascular risk such as BMI/obesity?
For example, maybe slim and metabolically healthy people drink whole milk, but overweight individuals choose skim milk to try ti lower their caloric intake.
In other words; maybe whole milk drinkers are generally healthier and this is what causes the reduced risk factors.
It is an interesting question that is hard to answer.
There is also the possibility that skim milk drinkers don't feel as satiated and replace whole milk calories with poorer dietary choices, which would also lead to adverse effects.
Key Point: Dairy fat appears to have an inverse relationship with cardiovascular risk. Thus, whole milk may be more protective than skim milk.
There are both pros and cons of skim milk.
On the positive side, it offers a similar (ish) range of vitamins and minerals as well as a lot more protein per calorie.
However, I think that the negatives outweigh the positives.
Firstly, the nutrient profile is not as reliable as regular whole milk due to the lower concentration of fat-soluble vitamins.
Secondly, from systematic reviews, it appears that dairy fat consumption may be protective against metabolic disorders.
Lastly, whole milk tastes better and provides all the nutrients in their natural ratios.
Having said that, existing high-level studies don't show evidence of skim milk having adverse health effects, so it is not a terrible choice.
But at the end of the day, there is no reason to fear dairy fat and it actually has a lot of benefits.