Bioavailability - how sensible is it to combine vitamins?

Bioavailability - how sensible is it to combine vitamins?

Natural foods contain a colorful mix of vitamins. Capsules, on the other hand, often contain only a single vitamin. How well can the body absorb this isolated nutrient? Are combined vitamins the key to better bioavailability?

Bioavailability: Why not all vitamins and minerals are created equal

Did you know that beta-carotene (precursor to vitamin A) from raw carrots is barely usable by your body? On the other hand, if you eat the vegetable chopped and with oil, you can absorb a much larger portion. This is due to the difference in bioavailability. Bioavailability indicates how well your body can utilize a nutrient, and this depends on several factors.

Factors that influence the bioavailability of nutrients are:

  • Preparation and digestion (e.g., some proteins are denatured during digestion).
  • Competing substances (e.g., inhibition of zinc absorption by copper and iron)
  • Complexing agents (e.g., phytate inhibits iron absorption by forming complexes)
  • Inhibitors of complex formation (e.g., vitamin C promotes iron absorption by inhibiting the formation of iron-phytate complexes)
  • Fat-soluble substances (vitamins A, D, E, K and carotenoids) require fat for absorption
  • Chemical structure (many vitamins are not a single chemical compound, but a group. Thus, there are subtypes of vitamins that are more easily absorbed by the body).


Thus, not all vitamins are the same. Different forms with different bioavailability occur in nature. For example, there is vitamin K1 from plants, vitamin K2 from bacteria, and synthetic vitamin K3, each with several subforms. Vitamin preparations often contain artificial vitamins. Even the use of genetic engineering is permitted in artificial production. As a consumer, it's not easy to understand where a vitamin in a food supplement comes from.

At CLAV, we focus on the high bioavailability of our products and we do not use genetic engineering. Learn more about our philosophy.

Why a combination of vitamins is so useful

Vitamins do not occur in isolation, of course. In vegetables, fruits and the like, they are bound into a food matrix. The combination of vitamins, fiber, minerals and other plant substances is crucial for bioavailability. In natural foods, the combination is predetermined, but we can optimize this by smartly combining different foods. For example, iron from plant sources is more available if you drink a glass of orange juice (vitamin C) with it. If you complement your diet with vitamin supplements, it therefore makes sense to pay attention to a smart combination here as well.

People who suffer from a vitamin deficiency often turn specifically to single vitamin supplements. These are vitamin tablets or capsules that contain the missing vitamin. However, that's not always optimal. If, for example, you take vitamin D to influence the absorption of calcium, then you should actually also take vitamin K. This is because high vitamin D intake can contribute to vitamin K deficiency. The supplement then compensates for the vitamin D deficiency, but can create a new problem in the process.

Combining vitamins also makes sense if you consider common causes of deficiency:

  • Unhealthy diet
  • Eating disorder
  • Intolerances, inflammations in the gastrointestinal tract
  • Vegan or vegetarian diet
  • Increased need due to pregnancy and breastfeeding
  • Stress (increased need for B vitamins)
  • Smoking and alcohol consumption
  • Medication and birth control pills


In all of these cases, individuals are lacking not just one vitamin, but several nutrients. A healthy diet together with a combination of vitamins can compensate or prevent the deficiency.

Which vitamins should be combined?

What you should bear in mind when taking different vitamins

If you decide to take a combination of vitamins, you can either rely on ready-made mixtures or take several mono-preparations at the same time. In the latter case, you should be well informed about how the two supplements work together and influence each other. If, on the other hand, you go for a ready-made combination, a transparent and trustworthy manufacturer is recommended.

In the production of our products, we always focus on high bioavailability. Thus, in addition to vitamins, our products often contain secondary plant substances that promote the absorption of vitamins and act as antioxidants to protect against oxidative stress. We believe that this combination is the key to better health.

When choosing capsules, other factors such as production without animal testing, genetic engineering or vegan supplements may be relevant to the decision. You can get this information on the packaging of the products.

In fact, there are also vitamins and minerals that should not necessarily be combined because, for example, they are absorbed through the same systems. This is the case with magnesium and calcium. You should take these micronutrients at intervals to get the most out of them. Folic acid absorption is also affected by zinc. Here, the bioavailability decreases with simultaneous intake.

5 typical mistakes when taking dietary supplements

With a correct intake of dietary supplements you can positively influence the bioavailability. To do so, avoid these mistakes:

  1. Taking them on an empty stomach: this makes sense with some medications, but not with most vitamins. It is therefore better to take vitamin capsules with your meals. You can find detailed information on the correct use on the packaging.
  2. Choose the right time of day: B-complex and vitamin C are more stimulating vitamins, ideal for the morning. Magnesium, on the other hand, is better suited for the evening, as it is said to improve sleep.
  3. Combination with medications: If you need to take medications, then you should use them with time distance from supplements, because interactions are possible. This can increase or decrease the effect of the medication or trigger other effects. You can find information about interactions in the package insert of the medication. You can also ask at the pharmacy or doctor's office.
  4. Combining vitamins but living unhealthy: Supplements cannot compensate for an unhealthy lifestyle. Therefore, set your complete diet to healthy. Exercise and relaxation also contribute to a good balance in the body and health.
  5. Take vitamins with coffee: Coffee and tea can affect the bioavailability of vitamins and minerals. Vitamin capsules are best taken with still water.
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