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October 22, 2019 9 min read
Bioavailability is a term you likely stumbled upon if you’ve done any research or googling on supplements prior to buying (which is always a plus!). However, it may have remained unclear as to what brands actually mean when talking about the elusive term, ‘bioavailability’. Although it could be considered a scientific term, it is still possible to define bioavailability in layman’s terms, avoiding unnecessary confusion - which is precisely the objective of this article.
Simply put, the level of bioavailability determines the amount of the nutrient the body is actually able to utilize. What proportion of the nutrient or active ingredient reaches the cells or parts of the body in need. Therefore, if you’re consuming a supplement which isn’t optimized in terms of bioavailability, you can expect a significant amount of the nutrient to be lost - especially when it bypasses the digestive system. Not really what most people have in mind when purchasing their supplements, right? Now, let’s get into a more detailed overview of bioavailability, as well as factors affecting it.
When choosing supplements, there are a lot of factors that go into making a purchasing decision including ease-of-use, cost, customer service, and flavor. Although these certainly do make a difference, two often-overlooked factors which should be prioritized are nutrient content, and of course - bioavailability of these nutrients, scientific evaluations in regard to toxicology and nutrient bioavailability show.
By definition, a supplement, as the name itself implies, is intended to act as a supplement to the diet, containing at least one mineral, vitamin, amino acid, herb, or a combination of these. However, in order for a supplement to release its full potential, it must be bioavailable, a study on bioavailability of bioactive food compounds finds. So, how could we define bioavailability?
The level of bioavailability is a measurement that represents the rate of absorption of a certain compound or a drug, as well as the extent of their availability. It is, therefore, considered a priority in the bioefficacy of dietary products. Basically, how well does a supplement actually work when you take it. However, bioavailability isn’t easily achieved, as it is a rather complex process that entails a number of stages.
There are several factors influencing the bioavailability of a supplement, as it is not determined solely by product content and the technology behind it. Bioavailability also depends upon the host - that being the individual consuming the supplement. According to a study conducted by E. A. Yetley, the extent and rate of absorption and availability of a nutrient are largely affected by the nutrient status of the host. When it comes to host factors affecting bioavailability, they are influenced by gender, age, physiological state, genes, activity, as well as gut microbiota composition of an individual.
While different forms of certain nutrients can vary in bioavailability, the interaction between different nutrients may also impact bioavailability. For instance, combining vitamin C with inorganic iron may enhance the bioavailability of iron, while levels of iron have been shown to peak with a decreased uptake of magnesium and calcium, a study on Multivitamin and multimineral dietary supplements finds. (For more information on supplement interactions, make sure to check out our in-depth guide.)
Bioavailability may also be influenced by metabolism, cellular transporters, molecular transformations, as well as the presence and content of other nutrients (for instance, adding a small amount of fat or oil will enhance the bioavailability of fat-soluble carotenoids), the aforementioned study finds.
Furthermore, a study on the use of lipid nanocarriers suggests that bioavailability may be negatively affected by chemical instability, low bioaccessibility, as well as impaired gastrointestinal (GI) absorption. In addition to these factors, many other factors, including erratic absorption profiles and dose-independent absorption may further jeopardize bioavailability of oral supplements.
Now that it’s pretty clear that you should prioritize bioavailable supplements for maximum efficiency, let’s talk a little bit about antioxidantsand why you should supplement with them in the first place.
You’ve probably heard of free radicals - damaged, highly reactive molecules responsible for oxidative stress, which is the result of an imbalance of oxidants and antioxidants. In order to combat free radicals and prevent oxidative stress, antioxidants in form of supplements are required, due to their prophylactic and therapeutic activity.
Oxidative stress has been linked to numerous conditions, including diabetes, cardiovascular conditions, neurodegenerative conditions, as well as premature aging. The good news is that our body is equipped with sets of scavengers (enzymatic, lipophilic radical, and hydrophilic - including glutathione) which represent our protective barrier. The bad news is that our defense system is not fully equipped, as we require dietary antioxidants, especially vitamin C, which cannot be manufactured naturally.
Antioxidants are of utmost importance for human health, as their primary role is as a defense mechanism which cannot function without dietary supplies. Therefore, when supplementing with antioxidants, you want to ensure that you’re getting the adequate amount, hence the significance of bioavailability of these supplements.
Bioavailability of dietary antioxidants may be affected by numerous factors, including compromised permeability and solubility, GI degradation, and first-pass effect. Many antioxidants in conventional supplement form cannot penetrate the cellular plasma membrane, in addition to having poor stability and short plasma half-life, a study conducted by D. V. Ratnam et al. suggests.
Therefore, in the face of continuous environmental pressure, with the addition of an imbalanced modern diet, proper antioxidant supplementation offering modern delivery modes is pivotal.
Vitamin C, also known as ascorbic acid, is a well-known antioxidant supplement. However, the dose of vitamin provided by conventional forms of vitamin C rarely suffices for the required amount, due to their poor biopharmaceutical composition and compromising factors such as poor solubility, permeability, as well as the first-pass effect before the nutrient even reaches the systemic circulation.
While vitamin C is better absorbed in small doses, the absorption decreases as a result of dose decreasing, which may sound rather counterintuitive. A study by D. V. Ratnam finds that this decrease in absorption may be a result of saturated transport mechanism, since the nutrient is transported by sodium-dependent vitamin C transporters.
When it comes to the absorbance of conventional forms of vitamin C, it has been shown to decrease with dose enhancement, as the bioavailability of doses of 30, 100, 200 and 500 mg was 87%, 80%, 72% , and 63%, respectively, the previously mentioned study finds. Furthermore, the same study found that, with a dose of 1250 mg of a conventional oral vitamin C supplement, less than 50% was absorbed, while the majority of the absorbed quantity was excreted in the urine.
What’s more, the stability of a traditional vitamin C supplement has also been called into question. Namely, vitamin C in the form of tablets is considered stable for 20 weeks, but its stability may be affected by various factors, including constant bottle opening and storage at 25 °C. These storage conditions have led to a significant change in vitamin stability, as they resulted in a loss of vitamin C up to 2%.
Novel Drug Delivery Systems (NDDS) represent one of the innovative strategies for bioavailability improvement, aiming for good bioavailability, stability, as well as selectivity to impaired cells. Furthermore, NDDS are considered to be the most convenient supplementation choice for oral administration.
However, a particular form of supplementation that has been getting more and more attention and recognition is liposomal encapsulation. According to a study on liposomal-encapsulated ascorbic acid, Liposomal Vitamin C has been found to provide a larger amount of circulating concentrations of vitamin C, when compared to orally administered unencapsulated vitamin C.
So, what exactly are the advantages of choosing all-natural Liposomal Vitamin C over your conventional supplement? As a study conducted by J. Duconge and colleagues states, a liposomal formulation of vitamin C allows the vitamin to be absorbed through an alternative pathway, avoiding the carrier-mediated transport in the small intestine which is where the nutrient could be dissolved and wasted. Furthermore, the same study finds that liposomes are able to target the lymphatic system, leading to enhanced bioavailability.
Glutathione has the reputation of the most powerful antioxidant in the human body, as it is the most abundant naturally manufactured detoxifier combatting free radicals. What makes glutathione irreplaceable is its pronounced role in the immune system, since it is the main regulator of oxidative stresscaused by free radicals.
Furthermore, a randomized controlled trial of oral glutathione supplementation suggests that the protective role of glutathione is multilayered, as it not only preserves the cells, but also promotes detoxification of toxins while regulating protein function.
It is critical for optimal human health to maintain adequate glutathione levels, as even minimal impairment could significantly affect our immunity, leaving the door open for xenobiotics and oxidative stress, the aforementioned study finds. In addition, low levels of glutathione could be attributed to many factors, including exposure to toxins, drugs, as well as poor nutritive choices.
When it comes to optimizing glutathione levels, quality oral supplementation such as Reduced Liposomal Glutathione has been recognized as a powerful strategy in increasing intracellular glutathione. However, what may be considered a potential setback when it comes to dietary glutathione is that traditional forms of this supplement usually do not suffice for the needed amount.
In order to test the bioavailability of conventional oral glutathione forms by following biomarkers of systemic oxidative stress, Allen J. and colleagues performed research which included 39 participants. By the end of the study conducted over a period of 4 weeks, none of the volunteers experienced a change in glutathione status, which was a clear indicator that the dose provided by the supplementation was insufficient.
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Yet another study conducted by R. Sinha et al. confirmed that the form does matter when it comes to glutathione supplementation. In this study, the researchers opted for Liposomal Glutathione in order to determine the efficacy of liposomal technology. As opposed to the previously discussed case, there were significant changes noted in glutathione status, oxidative stress biomarkers, and immune function.
Namely, after only 7 days of supplementing with a liposomal form of glutathione, glutathione levels were substantially enhanced, whereas after one more week they peaked (40% in whole blood, 28% in plasma, 25% in erythrocytes, and 100% in PBMCs). As far as oxidative stress biomarkers are concerned, supplementing with highly bioavailable Liposomal Glutathioneresulted in a decrease of impressive 35% in plasma 8-isoprostane and 20% in oxidized:reduced GSH ratios, followed by a significant enhancement in immune function markers.
Try to think of bioavailability this way: a nutrient is a high-priority package addressed to you. If you choose a quality bioavailable supplement, that being a professional delivery service, you expect the nutrient to be delivered into your bloodstream, and the package - to your doorstep. Choosing a conventional supplement that does not prioritize bioavailability means that you can expect the delivery guy to completely ignore the address and throw your package away.
Finally, it is safe to conclude that when it comes to supplementation, form definitely does make a great difference. Make sure to position bioavailability high on your list of priorities for supplementation, keeping in mind that if the nutrient is not delivered - but rather wasted - what’s the whole point of supplementing in the first place? For more all-natural supplements, head over to our online store.
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