Lactose intolerance

Intolerance to milk-containing foods is common and increases with age. This is thought to be because as we get older, our need to digest milk declines (which we would originally have only consumed from our mother’s breast).

The majority of the world’s population starts to decrease their ability to digest milk by the age of 3-5 years. This trend then continues as we get even older; in one study, around half of adults over 50 were lactose intolerant and around a quarter were under the age of 50, although this does vary between ethnic groups and Northern Europeans seem to have one of the highest lactose tolerances (Rao et al., 1994, Montgomery, Grand and Buller, 2015).

Milk intolerance is caused by low levels of the enzyme ‘lactase’ which breaks down the milk sugar known as ‘lactose’. This is usually due to a genetic trait, which means that we don’t produce enough of the lactase enzyme anymore (Montgomery, Grand and Buller, 2015).

This matters because lactose sugar needs to be broken down into two smaller sugars, glucose and galactose, before it can be absorbed as energy.

If this breakdown doesn’t happen, then the lactose travels onwards from the small bowel into the large bowel. In those who don’t have good lactase enzyme activity, around 75% of the unabsorbed lactose sugar will pass into the large bowel (Montgomery, Grand and Buller, 2015).

When unabsorbed lactose reaches the colon it is fermented by the gut bacteria, producing gas. This can distend and stretch the bowel walls, leading to discomfort and bloating, two of the classical signs of lactose intolerance. The higher sugar load of the large bowel also draws water into the gut, which can sometimes lead to loose stools or diarrhoea (Montgomery, Grand and Buller, 2015).

The symptoms of lactose intolerance may include the following (noticed after eating at least two servings of dairy / day)*

• Long-term problems with diarrhoea
• Abdominal pain or discomfort
• Bloating
• Flatulence

*Note: These symptoms are very non-specific, so if you are suffering from any of the above, or are worried you might have lactose intolerance, do see your GP to just check there is nothing else that might be going on. This is especially important in children.

Lactose intolerance & yoghurt / cheese

Processing milk into yoghurt or cheese may reduce the amount of lactose sugar it contains. For example, when making yoghurt, some of the lactose is fermented to produce lactic acid, which gives yoghurt its characteristic tangy taste.

Therefore, some people who can’t tolerate milk particularly well due to lactose intolerance may find that they are able to eat small portions of yoghurt or cheese. This will always vary from person-to-person.

Inflammation

The degree to which dairy products can result in inflammation is variable depending on lots of individual factors, perhaps the most important being in those people who have an allergy to milk.

If we eat foods that our immune system reacts to (called a ‘hypersensitivity’ reaction), this can lead to a pro-inflammatory state (Bordoni et al., 2015). It is sensible in those instances to avoid consuming dairy products. If in doubt, ask for professional advice on this.

However, according to the findings of a review on the topic, dairy – particularly fermented dairy products (like yoghurt & cheese) – could also have some anti-inflammatory effects. This may be, in part, due to the bacteria they contain, perhaps interacting with our own gut microbiota (which we know plays a key role in modulating and communicating with the immune system) (Bordoni et al., 2015).

Fractures

The idea that high milk consumption directly reduces the risk of broken bones, particularly as we age, has been questioned in recent years.

A British Medical Journal study reported that high milk consumption does not necessarily protect against fractures and for women in particular, might even increase risk (Byberg et al., 2014). Further studies have had more neutral effects, however, while others have suggested a slight reduction in the risk of having a hip fracture in women who drank more milk (Lamarche et al., 2016).

Again, more research is needed (especially amongst different ethnic groups, who may have higher or lower rates of lactose intolerance).

In the meantime, however, the Royal Osteoporosis Society has some useful articles on Looking After Your Bones (and specifically on Nutrition for Bones). theros.org.uk/.

If you’re interested in the links between dairy and bone health in children, take a look at this NHS article on ways to ‘boost your child’s bone health’ if you’d like more information: https://www.nhs.uk/live-well/healthy-body/bone-health-in-children/

Acne?

I personally found that my acne vastly improved without dairy.

I have often queried if this happened due specifically to the reduction in dairy, or because I replaced that dairy with lots more fresh fruits and vegetables, or perhaps a combination of the two. But I was interested to read this article recently, which gives an interesting take on a potential mechanism underlying the link between dairy and acne: examine.com/

As always, it is each to their own and it’s important to be in tune with our own bodies. The link between diet and acne is still a contentious one.

It’s worth mentioning, however, that I am careful to ensure I am replacing the nutrients of any foods I remove (from whole food sources where possible), as well as looking more broadly at my lifestyle. Stress and poor sleep, for example, are other big acne triggers for me.