THE TRUTH BEHIND LACTOSE

So, you’ve been experiencing bloating, stomach cramps, and gas? I’m sure you’ve heard of friends who experienced similar symptoms and cut out dairy products, and perhaps you're considering following suit. This article aims to give a no-nonsense breakdown of all things lactose, cover common misconceptions about this intolerance, and give some important considerations for the removal of certain dairy-based products from your diet.

We are going to start by stripping the topic way back: what exactly is lactose? Put simply, lactose is the sugar present in dairy products. It falls in the same category as other saccharides (sugar molecules). Lactose is classified as a disaccharide, meaning it is composed of two sugar molecules (galactose and glucose) molecularly bound together through a glycosidic bond. 

Lactose intolerance is your body’s inability to digest lactose. This happens when your body doesn’t produce enough lactase, the enzyme which breaks the bond between the glucose and galactose. As a result, the undigested lactose will ferment as it sits in the gastrointestinal tract. The fermentation of lactose produces gas which causes bloating, stomach-ache, digestive issues, nausea, and diarrhoea.

At birth almost all humans possess the ability to digest lactose, but as we age this ability decreases. Approximately 75% of the adult aged population present with an inability to digest lactose to some degree. 

The ability to digest lactose throughout adult life occurred with a genetic mutation approximately 10,000 years ago; this mutation enabled humans to continue to consume dairy based products as a food source later in life. This genetic mutation spread through livestock-rearing populations, which is why the ability to digest dairy products varies greatly across different ethnic groups. 

A milk allergy or cow’s milk protein allergy (CMPA) is significantly different from lactose intolerance, however based on the symptoms they can be easily mistaken. CMPA involves the body’s immune system reacting to the milk protein, which results in the same gastrointestinal issues as lactose intolerance. The key difference between the two is stage of onset. Lactose intolerance is extremely rare in children under the age of two, whereas CMPA usually develops in the first year of life.

The first and most important thing to do is seek advice from a health professional. Getting a referral from your GP to see a dietitian or registered nutritionist is essential. These health professionals will help correctly diagnose and create a management plan moving forward. 

There are three common strategies people employ: 

1) Continue to consume dairy-based products, despite negative symptoms. 
2) Completely remove all dairy-based products.
3) Consume a small amount of dairy-based products so as to not trigger symptoms. 

Before discussing these practical approaches, we are going to break down the epidemiological effect of the presence of lactose , lactase deficiencies, and the results of gastrointestinal deficiencies. 

It is important to remember that the human gut is highly adaptable, essentially this means it responds to the foods which we consume. If certain foods are regularly consumed, then the body will upregulate the genes involved in coding for the enzymes required to digest these foods. 

The same is true for lactase; if an individual is consuming dairy-based products then the body will continue to produce the lactase enzyme. However if dairy-based products are completely removed, the body will downregulate the production of lactase. This results in the intolerance becoming more severe. 

So, we have discussed the importance of continuing to consume dairy-based products, but what are the negative effects of gastrointestinal distress? Besides the obvious discomfort associated with bloating, stomach-ache, diarrhoea and nausea, there are secondary effects on nutrient absorption. The bloating causes the villi and microvilli of the intestines to lay flat. Normally these act like fingers in the intestine, helping the movement of food and increasing intestinal surface area. With the decrease in surface area the body’s ability to digest and absorb nutrients is significantly decreased. 

Relating this information back to the practical strategies mentioned above, it’s considered best practice for an individual to not completely remove all lactose-containing products. Instead, it is beneficial for small amounts of low lactose products to be consumed in amounts which do not trigger symptoms. The amount each individual can consume will vary depending on their individual level of sensitivity. 

Common low lactose products are:

- Hard cheeses (cheddar, swiss, halloumi)
- Yoghurts
- Low lactose milks and ice creams
- Whey protein isolate
- Kefir based dairy products

Many dairy-based products are important sources of calcium within our diet, so if you’re avoiding these products it is important that you replace the lost calcium from another source. There are a range of specialist foods which can help ensure nutritional requirements are met. Calcium is also naturally present in a number of other foods, which makes it relatively easy to meet your calcium requirements through certain choices.

The following foods are good sources:

- Calcium fortified alternative milks (almond, soy, oat etc)
- Calcium fortified orange juice 
- Calcium fortified breakfast cereals 
- Tofu
- Sardines, anchovies, salmon
- Almonds and sesame seeds

The presence of certain molecules can impact the absorption of others. Vitamin D, sometimes called the sunshine vitamin, plays an important role in maximising absorption of calcium. Additionally, smoking and excessive caffeine intake can inhibit the absorption of calcium.

Gut health is a hugely popular topic at the moment, and creating bacterial diversity in the gut is going to be largely beneficial for people’s health. There are two main strains of bacteria living in the gut; bifidobacterial and lactobacilli. Having a large number of Bifidobacterium is considered ‘beneficial’. Cross-sectional research looking at populations who regularly consume lactose vs those that do not has shown that those individuals who do consume dairy-based products as part of their diet have greater amounts of Bifidobacterium. Although this research is still relatively young and requires further evidence it has initially shown strong links.