Is dairy good for you?

Growing up strong 

Growing up, most of us can recall happily drinking milk, either by the glass, with cereal for breakfast or with cookies as a snack. Mum and dad promised that if we drank our milk, we’d grow tall and strong with healthy bones. On TV ads we would see kids ecstatically drinking milk, a guaranteed path to strong bones and muscles. 

Yet today, dairy’s reputation in the media is incredibly confusing and unclear, to say the least. Depending on the latest fad diet or recently published study, dairy is either a superfood or poison to avoid at all costs. So what are the facts? Is dairy good for you or bad for you? 

The short answer is that dairy isn’t absolutely necessary in the diet for most healthy grown adults. However, for many people, it is an easy way to cover their daily requirements for calcium, vitamin D and protein for optimal functioning of the heart, bones and muscles. There are non-dairy alternatives available to meet nutritional requirements, we will touch on this later.   

A source of calcium and protein 

Dairy products such as milk, yoghurt and cheese are good sources of calcium. Calcium is an essential mineral required for healthy bones, reducing the risk of fractures and osteoporosis later in life. In fact, women over the age of 50 and men over the age of 70 have increased calcium requirements compared to their younger counterparts. Some countries fortify milk with vitamin D, which we also need to maintain healthy bone mass. 

Moreover, older adults need protein to protect against age-related loss of muscle mass and strength, also known as sarcopenia. Dairy can be a good source of protein for this population. So that means dairy is good for you, right?

The answer is not so black and white. In fact, current scientific evidence is mixed with regards to the direct impact of dairy on human health. Some researchers state that too much dairy can be harmful, whereas other studies have shown health benefits derived from regular consumption of dairy products.  

Is low-fat better than full-fat?

The current guidelines from the American Heart Association recommend that adults should consume low-fat or fat-free dairy products when possible rather than full-fat varieties. 

This is due to the saturated fat content typically found in dairy, especially in products with higher fat percentages such as cheeses and cream. 

However, it appears that new research has debunked this theory. In fact, it seems that full-fat dairy products (in moderation) may not be something to fear after all. 

In 2018, researchers presented a report at the Congress of the European Society of Cardiology which involved 20 studies including approximately 25000 participants. The report didn’t find any association between the consumption of most dairy products and cardiovascular risk. The only exception was milk consumption. However, the results suggested that consumption needed to be very high (about one litre/day) in order for it to  be linked to increased cardiovascular risk.(1)

Moreover, there is some evidence to suggest that specific types of dairy may have a protective effect against cardiovascular risk. In fact, the British Journal of Nutrition published a study looking at the relationship between fermented dairy product consumption and risk of heart disease. The results showed that participants who consumed higher amounts of fermented dairy foods such as yoghurt had a lower risk of developing cardiovascular disease compared to individuals who ate lower amounts.(2) It appears that specific types of dairy may be more good for you than others.

Bone health and peak bone mass

Calcium is indisputably linked to bone mass and health. Whether or not dairy consumption is the healthiest way to get calcium in the diet is another question. Various factors determine risk of fractures, including calcium intake, vitamin D levels, bone mass, bone loss, geometry and microstructure which are the product of peak bone mass. Peak bone mass refers to the point in time where our bones have fully developed and reached the “peak” of their mass. In other words, they are as strong as they will ever be! We normally reach this peak at the end of puberty. In fact, for this reason children and teenagers must have adequate calcium intakes to ensure healthy bone development. 

Childhood and adolescence are a crucial window in which bones develop at an exceptionally fast rate. Calcium and protein intake specifically have a major impact on bone growth. Therefore adequate intakes of calcium and protein are essential to achieve optimal peak bone mass in developmental years, as well as to prevent bone mineral loss in older age. 

Unfortunately, young girls are especially at risk of low calcium intakes which can negatively impact their peak bone mass and cause issues later in life. If you are a parent or carer of a teenage girl, please make sure she is getting enough calcium in her diet. 

If you are concerned about calcium intake or any other nutrition related issue or eating disorder (increasingly common in young people), I strongly encourage you to reach out to a registered dietitian. They can advise you on the best way to approach the situation.

Related reading

• Is a low fat diet healthy?
• How much protein should a balanced diet contain per day?

Food first: food over supplements

Dairy products contain various nutrients which are crucial for healthy bones, these include calcium, protein, vitamin D as well as potassium and phosphorus. Studies have shown a positive association between dairy intake and bone mineral content.(3) In addition, fortified dairy products have shown a more positive impact on bone health compared to calcium supplementation alone. Once again, a “food first” approach is the winner!

Is dairy protective against bone fractures?

It is unclear whether dairy product consumption is protective against hip fractures, which are very common amongst the elderly. However, yoghurt consumption seems to have a somewhat positive protective effect on this specific type of fracture. Therefore it seems that some types of dairy may potentially play a role in reducing bone fractures in later life.  

Dairy and bone health: mixed evidence

Despite the undoubtedly beneficial nutrients in dairy foods (also found in other non-dairy foods), it is unclear whether dairy foods specifically promote bone health in all population groups. Furthermore, not all dairy foods are equal nor do they have the same impact on health.

As you can imagine, low-fat greek yoghurt and whipped cream have quite distinct nutritional profiles. The American Journal of Clinical Nutrition published a study in which the researchers conducted a review of the evidence surrounding dairy foods and bone health.(4)

The study aimed to understand whether the recommendation that dairy foods should be consumed daily for bone health aligns with the scientific evidence. The evidence was examined across all ages, genders and ethnicities. 

The researchers classified the outcomes of the studies based on the robustness of the evidence, either as favourable, unfavourable or not statistically significant. The overall ratio of favourable to unfavourable effects in the more robust studies was 2.0.  

It must be noted that males and ethnic minority groups were significantly underrepresented across the studies.  Moreover, there was a large variation between the nutritional value of dairy foods and specifically the nutrients known to affect calcium excretion as well as bone mass. It was found that milk and yoghurt are potentially beneficial whereas cottage cheese may adversely affect bone health. 

Once again, the evidence is mixed and makes it challenging to draw absolute conclusions. In fact, most of the stronger evidence studies had non significant outcomes. Interestingly, white women below the age of 30 were the most likely to benefit from dairy foods for bone health. 

Overall, the lack of data for males and minority ethnic groups hinders the possibility to make any conclusions regarding the effects of dairy on bone health for the general population. 

What if I’m lactose intolerant?

Lactose intolerance refers to the symptoms associated with consuming lactose-containing dairy foods. This condition can affect anyone regardless of age, gender or ethnicity, however the most common cause is genetic.(5) In fact, lactose intolerance disproportionately affects certain geographic areas of the world, including the Mediterranean and East Asia. People with lactose intolerance lack the intestinal enzyme lactase which breaks down lactose. 

Lactose maldigestion is commonly interpreted as lactose intolerance (i.e.GI symptoms) and therefore many individuals eliminate lactose as a way to reduce symptoms. However, self-diagnosis and complete avoidance of dairy products can lead to nutritional deficiencies. 

Moreover, we should take care when making plant-based substitutions and ensure that nutritional requirements are met. A word of advice when selecting plant-based milks is to always look at the calcium content. Ideally, 100mg/100ml is considered a good source of calcium. If your plant-based milk of choice is lower than this, just be aware that you shouldn’t rely on this as a milk substitute for your calcium requirements. 

Also, plant-based yoghurts are often filled with additives and sugars, with low protein and calcium, so be sure to read the nutritional labels. Some yoghurts such as coconut yoghurt also contain very high levels of fat and no probiotics! 

As a point of reference, a full fat dairy greek yoghurt usually contains no more than 4 t