Food supplements: How can you recognize good quality? | Bioavailability

Posted: May 23, 2024
In short
Bioavailability is the share of a nutrient that reaches your bloodstream and can be used by your body. It depends on the chemical form, the food and what you take the nutrient with. In volunteers, 20 mg of piperine from black pepper raised the bioavailability of curcumin by 2000% (Shoba et al., 1998). Vitamin C counteracts substances that block iron absorption (Hallberg et al., 1989), and vitamin D3 taken with a meal containing fat reached 32% higher peak blood levels than with a fat-free meal (Dawson-Hughes et al., 2015).

Updated on: September 30, 2026

⏱ 8 min read

Have you ever wondered what is really important when taking dietary supplements? What should you pay attention to?

We always do our best to provide you with the best quality and highest value products. One point we pay particular attention to is the so-called bioavailability. 

Bioavailability ... but what exactly does that mean?

The bioavailability of a nutrient indicates how well it can be absorbed and utilized by the body. High bioavailability is extremely important for a balanced and healthy diet. 

In nutrition, for example, lycopene from processed tomatoes is more available to the body than lycopene from raw ones. When volunteers ate tomato paste with a little oil, their peak blood levels of lycopene were 2.5 times higher than after the same amount of lycopene from fresh tomatoes (Gärtner et al., 1997). Digestion also determines how well nutrients can be absorbed. 

Unfortunately, there are also factors that make the absorption of certain nutrients more difficult. Phytate from cereals and legumes, for example, lowered the absorption of iron from bread rolls by 18% to 82%, depending on the amount (Hallberg et al., 1989). 

But bioavailability is not only relevant for nutrition, it is also a key term in medicine. There it describes how much of a medicine reaches the bloodstream unchanged. A medicine given directly into a vein has a bioavailability of 100% by definition, while tablets and capsules usually reach less because part of the dose is not absorbed or is broken down in the gut wall and liver first. 

What affects bioavailability?

Several things decide how much of a nutrient your body actually takes up:

  • Processing and the food matrix: lycopene from tomato paste is better available than lycopene from fresh tomatoes (see above).
  • Fat in the meal: fat-soluble vitamins need fat. In a randomised trial with 50 older adults, a single dose of vitamin D3 taken with a fat-containing breakfast led to 32% higher peak levels in the blood than the same dose taken with a fat-free breakfast (Dawson-Hughes et al., 2015).
  • Helpers and blockers: vitamin C improves iron absorption, while coffee and black tea lower it (more on this below).
  • The chemical form: the same vitamin can exist in several forms that the body absorbs and uses differently, as vitamin K2 shows further down.
  • The person: absorption also differs from person to person. In a pilot study with lipoic acid, blood levels varied much more between older adults than between younger ones (Keith et al., 2012).

Vitamin D3, vitamin K2 and magnesium are a good example of nutrients that are often taken together. Vitamin D contributes to the normal absorption and use of calcium, while vitamin K and magnesium contribute to the maintenance of normal bones. Our set combines all three.

Herbano set with vitamin D3 capsules, vitamin K2 MK-7 capsules and magnesium complex capsulesView the Vitamin D3, K2 and Magnesium Set  ➜
✓ Vitamin D3 + vitamin K2 MK-7 all-trans + magnesium complex

Why are certain products not available from us as pure products?

There are nutrients that our body can use as a pure product. However, there are also those that only become interesting for our health in combination with other nutrients. It is precisely this combination that leads to significantly improved absorption - we can make better use of the substance.

Our top 3 combinations with maximum bioavailability

1) Turmeric with piperine

Turmeric is primarily known for its valuable secondary plant substances, known as curcuminoids. Curcumin, the yellow pigment of turmeric, has been associated with antioxidant and anti-inflammatory activities in research (Prasad et al., 2014). Our turmeric capsules contain Curcumin C3 Complex® with 95% curcuminoids. This is where piperine comes into play. We offer our turmeric capsules with natural black pepper extract: in healthy volunteers, 20 mg of piperine taken with 2 g of curcumin increased the bioavailability of curcumin by 2000% (Shoba et al., 1998). If you have a sensitive stomach or irritable bowel, the variant without piperine is the better choice.

2) Iron with vitamin C

Iron deficiency is one of the leading contributors to the global burden of disease and particularly affects children and women before the menopause (Pasricha et al., 2021). Part of the problem is that the body cannot always absorb iron from food well. So-called iron inhibitors reduce the absorption of iron. These include coffee and black tea: in a study with adult volunteers, black tea lowered iron absorption from a bread meal by 79 to 94% (Hurrell et al., 1999). Vitamin C works in the opposite direction and significantly counteracted the inhibiting effect of phytate (Hallberg et al., 1989). We always offer our iron products with vitamin C. For example, our iron capsules contain natural vitamin C from acerola, and our iron juice combines iron with vitamin C and fruit juices. 

3) Resveratrol in combination with OPC and piperine

Resveratrol is mainly found in grapes and red wine, and its antioxidant and anti-inflammatory activities, among others, have been studied in animal and human models (Kuršvietienė et al., 2016). For our resveratrol capsules, we use trans-resveratrol. We were also able to supplement the formula with valuable OPC and piperine. In combination with OPC, the resveratrol formula has an even broader polyphenol spectrum. And piperine ensures that the resveratrol is not broken down so quickly and is available to the body for longer: in mice, adding piperine raised the peak blood level of resveratrol to 1544% and the total exposure to 229% (Johnson et al., 2011).

Our top 3 products at their best

But it is not only the right combination with other nutrients that can increase bioavailability. The actual form of the nutrient can also determine whether a nutrient can be utilized well or not.

1) R-alpha lipoic acid

Alpha lipoic acid has been gaining popularity for some time as a powerful antioxidant, particularly in the field of diabetes and polyneuropathy. The acid is available on the market as R-alpha lipoic acid, S-alpha lipoic acid or as a mixed product. For our R-alpha lipoic acid capsules, we use exclusively and 100 % the R-form. This is because only this is considered to be the body's own natural form (Keith et al., 2012). In a pilot study, older adults reached their highest blood level of lipoic acid faster with the R-form than with the mixed product (Keith et al., 2012).

2) Vitamin K2 MK7

Vitamin K contributes to normal blood clotting and to the maintenance of normal bones. It is often combined with vitamin D3, which contributes to the normal absorption and use of calcium. The vitamin can be divided into two forms, which have different bioavailability. As a dietary supplement, the form K2 MK-7 is more suitable than K2 MK-4, as it has a much longer half-life and is therefore available to the body for longer. In healthy women, MK-7 was well absorbed and could still be measured in the blood 48 hours after a single dose, while MK-4 at the same nutritional dose was not detectable at any time (Sato et al., 2012). And not only that, vitamin K2 MK-7 can also be divided into all-trans and cis, whereby only the all-trans form is biologically active (Lal & Berenjian, 2020). We only use the best form for our vitamin K2 capsules - vitamin K2 MK7 all-trans.

If you want to take vitamin K2 together with vitamin D3 and magnesium, our set brings all three together.

Herbano set with vitamin D3 capsules, vitamin K2 MK-7 capsules and magnesium complex capsulesView the Vitamin D3, K2 and Magnesium Set  ➜
✓ Vitamin D3 + vitamin K2 MK-7 all-trans + magnesium complex

3) Coenzyme Q10 Ubiquinol

Coenzyme Q10 is mainly used in energy production and as an antioxidant in the body. A distinction is made between ubiquinol and ubiquinone. Ubiquinol is the reduced form of coenzyme Q10 and a naturally occurring fat-soluble nutrient. In healthy volunteers, ubiquinol was significantly absorbed from the digestive tract, and blood levels rose with the dose over four weeks, without safety concerns in the standard tests (Hosoe et al., 2007). For our ubiquinol capsules, we use Kaneka ubiquinol, the form that was tested in this study.

Conclusion:

Bioavailability determines how valuable a nutrient is for us and our health and whether the nutrient is of any benefit to us at all. Care should therefore be taken to select the right form of a nutrient and, in certain cases, the right combinations of nutrients.

Frequently asked questions

What does 90% bioavailability mean?

It means that 90% of a dose reaches the bloodstream unchanged and can act in the body. The other 10% is either not absorbed or is broken down in the gut wall or liver beforehand. A medicine given directly into a vein has a bioavailability of 100% by definition.

Why is bioavailability important?

Your body can only use the part of a nutrient that actually reaches the blood. That is why the form of a nutrient and the right combination matter as well as the dose. Piperine, for example, raised the bioavailability of curcumin by 2000% in volunteers.

How can I increase bioavailability naturally?

Take vitamin D with a meal that contains some fat, and combine iron-rich food with vitamin C, for example from fruit or vegetables. Leave some time between iron and coffee or black tea. Processing can also help, as lycopene from tomato paste is better available than from fresh tomatoes.

Does taking with food improve bioavailability?

For fat-soluble vitamins such as vitamin D, yes: with a meal containing fat, peak blood levels of vitamin D3 were 32% higher than with a fat-free meal. For other nutrients it depends on the product, so follow the intake recommendation on the pack.

Does piperine boost bioavailability safely?

Piperine clearly increases the bioavailability of curcumin in humans and of resveratrol in animal studies. In the human study with 20 mg of piperine and 2 g of curcumin, no adverse effects were seen. If you have a sensitive stomach or irritable bowel, a variant without piperine is the better choice, and if you take medicines regularly, check with your doctor or pharmacist first.

Sources

Prasad, S., Tyagi, A. K., & Aggarwal, B. B. (2014). Recent developments in delivery, bioavailability, absorption and metabolism of curcumin: the golden pigment from golden spice. Cancer research and treatment, 46(1), 2–18. https://doi.org/10.4143/crt.2014.46.1.2

Shoba, G., Joy, D., Joseph, T., Majeed, M., Rajendran, R., & Srinivas, P. S. (1998). Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta medica, 64(4), 353–356. https://doi.org/10.1055/s-2006-957450

Heffernan, A., Evans, C., Holmes, M., & Moore, J. (2017). The Regulation of Dietary Iron Bioavailability by Vitamin C: A Systematic Review and Meta-Analysis. Proceedings of the Nutrition Society, 76(OCE4), E182. doi:10.1017/S0029665117003445

Kuršvietienė, L., Stanevičienė, I., Mongirdienė, A., & Bernatonienė, J. (2016). Multiplicity of effects and health benefits of resveratrol. Medicina (Kaunas, Lithuania), 52(3), 148–155. https://doi.org/10.1016/j.medici.2016.03.003

Packer, L., Witt, E. H., & Tritschler, H. J. (1995). alpha-Lipoic acid as a biological antioxidant. Free radical biology & medicine, 19(2), 227–250. https://doi.org/10.1016/0891-5849(95)00017-r

Møller, M., Gjelstad, I., Baksaas, I., Grande, T., Aukrust, I. R., & Drevon, C. A. (2017). Bioavailability and Chemical/Functional Aspects of Synthetic MK-7 vs Fermentation-Derived MK-7 in Randomised Controlled Trials. International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition, 87(5-6), 1–15. https://doi.org/10.1024/0300-9831/a000258

Failla, M. L., Chitchumroonchokchai, C., & Aoki, F. (2014). Increased bioavailability of ubiquinol compared to that of ubiquinone is due to more efficient micellarization during digestion and greater GSH-dependent uptake and basolateral secretion by Caco-2 cells. Journal of agricultural and food chemistry, 62(29), 7174–7182. https://doi.org/10.1021/jf5017829

Gärtner, C., Stahl, W., & Sies, H. (1997). Lycopene is more bioavailable from tomato paste than from fresh tomatoes. American Journal of Clinical Nutrition, 66(1), 116–122. https://doi.org/10.1093/ajcn/66.1.116

Hallberg, L., Brune, M., & Rossander, L. (1989). Iron absorption in man: ascorbic acid and dose-dependent inhibition by phytate. American Journal of Clinical Nutrition, 49(1), 140–144. https://doi.org/10.1093/ajcn/49.1.140

Dawson-Hughes, B., Harris, S. S., Lichtenstein, A. H., Dolnikowski, G., Palermo, N. J., & Rasmussen, H. (2015). Dietary fat increases vitamin D-3 absorption. Journal of the Academy of Nutrition and Dietetics, 115(2), 225–230. https://doi.org/10.1016/j.jand.2014.09.014

Keith, D. J., Butler, J. A., Bemer, B., Dixon, B., Johnson, S., Garrard, M., Sudakin, D. L., Christensen, J. M., Pereira, C., & Hagen, T. M. (2012). Age and gender dependent bioavailability of R- and R,S-α-lipoic acid: a pilot study. Pharmacological Research, 66(3), 199–206. https://doi.org/10.1016/j.phrs.2012.05.002

Pasricha, S. R., Tye-Din, J., Muckenthaler, M. U., & Swinkels, D. W. (2021). Iron deficiency. The Lancet, 397(10270), 233–248. https://doi.org/10.1016/S0140-6736(20)32594-0

Hurrell, R. F., Reddy, M., & Cook, J. D. (1999). Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. British Journal of Nutrition, 81(4), 289–295. PMID: 10999016

Johnson, J. J., Nihal, M., Siddiqui, I. A., Scarlett, C. O., Bailey, H. H., Mukhtar, H., & Ahmad, N. (2011). Enhancing the bioavailability of resveratrol by combining it with piperine. Molecular Nutrition & Food Research, 55(8), 1169–1176. https://doi.org/10.1002/mnfr.201100117

Sato, T., Schurgers, L. J., & Uenishi, K. (2012). Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal, 11, 93. https://doi.org/10.1186/1475-2891-11-93

Lal, N., & Berenjian, A. (2020). Cis and trans isomers of the vitamin menaquinone-7: which one is biologically significant? Applied Microbiology and Biotechnology, 104(7), 2765–2776. https://doi.org/10.1007/s00253-020-10409-1

Hosoe, K., Kitano, M., Kishida, H., Kubo, H., Fujii, K., & Kitahara, M. (2007). Study on safety and bioavailability of ubiquinol (Kaneka QH) after single and 4-week multiple oral administration to healthy volunteers. Regulatory Toxicology and Pharmacology, 47(1), 19–28. https://doi.org/10.1016/j.yrtph.2006.07.001

Important Notice

This guide is for informational purposes only and does not replace professional medical advice.

The content of the Herbano Health Editorial team is carefully researched and based on current scientific studies.

Content created with the support of artificial intelligence and edited by the Herbano Editorial team.