You’ve probably been told to spit into a cup, or even a plastic bag, and send it off for testing. Or maybe you’re being tested yourself, in which case you might be asked to place your cheek under the tube of your electric toothbrush.
The truth is that saliva samples don’t stay around forever, but they can still provide useful information when used correctly. Let’s take a look at what happens to these samples.
When we think about our body fluids, we tend to think of blood, urine, sweat and tears as the most important ones. We also know that blood contains antibodies against many viruses and bacteria, including HIV.
But there are other bodily fluids that can tell us a lot about ourselves – such as saliva, which we all produce every time we swallow. The first thing to note about saliva is that it doesn’t contain much water. It’s mostly made up of proteins, enzymes, fats and minerals. Saliva plays an important role in the digestion of food. The enzymes in saliva, such as amylase, break down carbohydrates into smaller molecules that can be easily absorbed by the body. Saliva also lubricates food, making it easier to swallow. There are also many other functions of it. Read this article to know about it.
This means that it’s very hard for any foreign objects to get mixed in with a saliva sample. So if you have a blood-borne virus, like HIV, then the chances of contaminating your sample will be minimal. But some viral infections do cross over from person to person through saliva, so this isn’t always the case.
Another thing to consider is the fact that saliva is often collected by mouth swabs, rather than by spitting into a cup or bag. Mouth swabs are typically placed on a card, but sometimes they’re left inside a tube in an envelope. This makes them more likely to pick up particles from the environment. And since saliva is mostly protein, that could lead to false positives.
So, in short, the answer to “how long does a saliva sample last?” is ‘as long as you want it to!’
In order to understand why this works, it helps to know how saliva gets into our mouths. When we eat something, it usually passes down our esophagus and into the stomach, where the acid breaks it down further. If it ends up in our throat, though, it goes through two different stages before getting swallowed.
First, it travels down our windpipe (called the pharynx), where it hits the back of our tongue (the epiglottis). Here, it slows down enough that it can be swallowed easily. Once swallowed, it continues down the esophagus until it reaches the stomach, where it mixes with gastric juices.
Once it’s in the stomach, the next stage begins, which is called peristalsis. Peristalsis is a wave of muscular contractions that push food along. In other words, if you put a bunch of saliva in your hand, it would move pretty slowly. But as soon as your muscles start contracting to push the saliva into your stomach, it starts moving faster and faster.
Your salivary glands, however, don’t really work like this. Instead, their function is to release fluid into the mouth, which eventually moves down into the esophagus.
Testing saliva
At this point, you may be wondering how exactly saliva tests are done. A saliva test involves collecting a small amount of saliva from your mouth, either using a cotton swab or by asking you to let some fall out naturally. Saliva is then analyzed for certain types of molecules.
One common type found in saliva is immunoglobulin A, or IgA. IgA is produced by B cells, which are white blood cells that help fight off germs and other invaders. IgA is also found in mucous, which is a thin, slippery substance that protects your body from things like dust, dirt and other substances. IgA is found in the lining of your digestive tract and also in your respiratory system. It’s one of the first lines of defense against invading pathogens.
IgA is found in both human and animal saliva. However, the levels of IgA in saliva change throughout the year. For example, the levels of IgA in children increase during the winter months, while they decrease during the summer months. This is because kids spend more time outdoors during the cold winter months, which puts them at increased risk of exposure to harmful organisms.
In addition to IgA, another molecule found in saliva is alpha-amylase. Alpha-amylase is an enzyme produced by your pancreas, which is responsible for breaking down starch into smaller pieces. These pieces are then absorbed into your bloodstream, allowing you to use the energy they contain to perform basic functions.
If you were diagnosed with diabetes, for instance, you’d need to monitor your blood sugar level regularly. One way to do this is to check for elevated levels of alpha-amylase in your saliva. Your doctor will check for this specific molecule – or any others – to make sure your blood sugar is within normal limits.
A third molecule found in saliva is secretory phospholipase A2 (sPLA2), which is involved in inflammation and immunity. It’s also found in breast milk. sPLA2 is released into the bloodstream when your immune system detects a pathogen or chemical that needs to be destroyed. But it turns out that sPLA2 is also found in saliva, and it increases in concentration after eating foods rich in fat. So if you ate a high-fat meal, your saliva would likely show elevated levels of sPLA2.
Finally, there’s kallikrein 4, which is normally present in human saliva at low concentrations. Kallikrein 4 is a serine protease that works by destroying other proteins. It’s also involved in wound healing, tissue degradation and bone resorption.
The good news is that none of the molecules mentioned above are associated with health problems. But it’s important to remember that each of these markers has its own purpose beyond just diagnosing disease. They can also give doctors insight into your diet and lifestyle choices – making it easier to create personalized treatment plans.
For example, a patient’s doctor might test his or her saliva for biomarkers linked to heart disease. This might include cholesterol, triglycerides, lipoproteins and other molecules that are related to cardiovascular health. After analyzing the results, the doctor will use this data to determine whether the patient should lose weight, gain weight or follow a more specific treatment plan.
And because saliva tests aren’t invasive, they’re also less painful than other diagnostic tools. Plus, saliva tests are simple, inexpensive and easy to administer. This makes them ideal for screening patients who haven’t yet received full diagnosis, or for monitoring their progress during regular care.
