Nutritional supplements can support your health and performance in the long term. But have you ever taken a closer look at the ingredients list? The active ingredients, i.e. vitamins or minerals, are usually the main focus - but the quality of the so-called fillers is often overlooked. However, they can have a major impact on the effectiveness, tolerability and even the long-term effects of your supplement.
So you're probably wondering why they're needed at all. An example: Vitamin D3 drops. The vitamin itself is dosed in minimal quantities, often in microgram ranges, which is why carriers such as oil or other fillers are necessary to ensure a practical dosage form.
Why are fillers used in dietary supplements
Fillers are essential in many supplements. They fulfill various important functions, such as:
- Ensuring dosage: Active ingredients such as vitamin K and D are required in such small quantities that they could not be dosed evenly without carriers.
- Improve absorption: Fillers such as oils help fat-soluble molecules to be better absorbed by the body.
- Increase stability: They protect sensitive active ingredients from oxidation or moisture.
- Create consistency: Fillers ensure a uniform texture for drops, powders or tablets.
- Facilitate the production process: They prevent lump formation, improve flowability and enable automated production.
What fillers are there, and do they have an effect?
Fillers vary greatly in their function and effect. Here are some common examples, including their advantages and disadvantages:
1. MCT oil (medium-chain triglycerides)
- Origin: MCT oil is usually obtained from coconut oil. It consists of medium-chain fatty acids, which are digested and metabolized faster than long-chain fatty acids.
- Function: MCT oil serves as a carrier for fat-soluble vitamins such as vitamin D, E or K. It improves the absorption of these active ingredients in the body.
- Benefits: MCT oil has been shown not only to increase the bioavailability of fat-soluble vitamins, but also to provide energy quickly without affecting blood sugar levels. It is processed directly in the liver and supports fat metabolism, which is particularly interesting for people on a ketogenic diet or with longevity goals.
- Drawbacks: High-quality MCT oil can be more expensive than alternatives such as soybean oil. In very high quantities, it can also cause digestive problems.
2. acacia fiber powder
- Origin: This powder is obtained from the resin of acacia trees.
- Function: It serves as a bulking agent and at the same time as a dietary fiber with prebiotic properties, which can have a beneficial effect on the gastrointestinal tract.
- Benefits: Acacia fiber is a soluble dietary fiber that is slowly fermented in the intestine. This promotes the growth of healthy intestinal bacteria and reduces flatulence compared to other fibers.
- Disadvantages: In high quantities, it can have a laxative effect, although this is less common than with other dietary fibers. Supplements with acacia fiber powder as a filler usually only contain very small amounts.
3. microcrystalline cellulose
- Origin: This filler is derived from plant cellulose.
- Function: Microcrystalline cellulose increases the volume of tablets and provides stability and binding.
- Advantages: It is tasteless, calorie-free and hypoallergenic. As it is not digested, it has no effect on blood sugar levels or metabolism. Its safety has been confirmed by the European Food Safety Authority (EFSA).
- Disadvantages: Microcrystalline cellulose offers no additional health benefits as it is not absorbed by the body.
4. Guarkernmehl
- Origin: This flour is obtained from the seeds of the guar plant.
- Function: Guar gum is used as a thickening agent and dietary fiber in food supplements and foods.
- Benefits: It has prebiotic properties and can support gut health by stimulating the growth of beneficial bacteria. It also stabilizes the consistency of powders and liquid supplements. Guar gum has also been shown to help regulate blood sugar levels by slowing down the rate at which carbohydrates are digested.
- Disadvantages: It can cause bloating or mild stomach discomfort in sensitive individuals, especially when consumed in large quantities. However, as with other fillers, it is used in food supplements to a very small extent.
5. Leinsamenmehl
- Origin: Linseed flour is produced by grinding linseed.
- Function: It acts as a fiber and bulking agent and provides additional omega-3 fatty acids.
- Benefits: Flaxseeds are known for their inflammation-modulating properties and support healthy digestion. They are also rich in lignans, which act as plant antioxidants and may have an effect on hormone balance. It has been shown that flaxseed meal can have a positive effect on cholesterol levels
- Disadvantages: In high quantities it can have a laxative effect or lead to flatulence, as it is very high in fiber.
6. Reismehl
- Origin: Ground rice grain.
- Function: Rice flour is used as a hypoallergenic bulking agent.
- Advantages: Rice flour is very inexpensive and gluten-free, making it particularly suitable for people with coeliac disease or gluten intolerance. It has a mild taste and is versatile in use.
- Disadvantages: It raises the blood sugar level and provides no additional fiber or nutrients that could increase the health value. Paradoxically, it is used by some manufacturers in products that are supposed to stabilize blood sugar and prevent insulin resistance .
7. Magnesiumstearat
- Origin: A compound of magnesium and stearic acid.
- Function: Used as a lubricant to prevent powders from sticking together during production.
- Advantages: It facilitates the production of capsules and tablets and improves their consistency.
- Disadvantages: Magnesium stearate has been criticized as it could inhibit the absorption of active ingredients in high quantities. However, there is no clear evidence to confirm this concern.
Füllstoffe in Nahrungsergänzungsmitteln
Füllstoff | Funktion | Vorteile | Nachteile |
MCT-Öl (Kokosbasis) | Carrier for fat-soluble active ingredients | Supports absorption, provides energy, no influence on blood sugar | More expensive, but also better than alternatives |
Akazienfaser Pulver | Ballast, bulking agent | Prebiotic, supports intestinal health, well tolerated | Can have a laxative effect in large quantities |
Microcrystalline cellulose | Stabilization, volume increase | Hypoallergenic, calorie-free, neutral taste | No additional health function |
Guarkernmehl | Thickening agent, dietary fiber | Promotes digestion, prebiotic effect, stabilizes powder | Can cause flatulence |
Leinsamenmehl | Ballaststoff, Omega-3-Quelle | Rich in fiber and omega-3, anti-inflammatory | May have a laxative effect in high quantities |
Olivenöl | Carrier for fat-soluble active substances | Natural carrier, stable, potentially anti-inflammatory | Can oxidize if not processed properly |
Reismehl | Volumenmittel | Gluten-free, hypoallergenic, well tolerated, inexpensive | High glycaemic index, low nutrient density |
Magnesiumstearat | Schmiermittel | Improves production efficiency | Can inhibit the absorption of active substances |
Maltodextrin | Binder, carrier | Extends shelf life, improves consistency | High glycemic index, can cause blood sugar spikes |
Siliciumdioxid (E551) | Anti-sticking agent, prevents lump formation | Safe in small quantities, improves production | No health benefits |
Sojaöl | Carrier for fat-soluble active substances | Favorable, widely used | Allergenic, often genetically modified |
Which supplements should you pay particular attention to the fillers in?
With some types of supplements, you should pay particular attention to the fillers they contain. The quality and properties of the fillers can influence not only the efficacy but also the tolerability of the product. Here are the most important categories:
Fat-soluble vitamins (z.B. Vitamin D, vitamin E, vitamin K)
- Why is it important? Fat-soluble vitamins require suitable carriers to improve their absorption in the body. Inferior fillers such as cheap oils (e.g. soybean oil) can oxidize or cause allergies.
- Recommended fillers: High-quality carrier oils such as MCT oil or avocado oil.
- What to look out for Look out for soybean oil or saturated synthetic fats, which can be potentially inferior or allergenic.
Probiotika und Präbiotika
- Why is it important Probiotic cultures are sensitive and require a stable environment. Fillers can influence their effectiveness or serve as prebiotic support.
- Recommended fillers: Acacia fiber or guar gum as prebiotic fiber.
- What to look out for Watch out for maltodextrin, as it can raise blood sugar levels and negatively affect the intestinal microbiome .
Mineralstoffe (z.B. Magnesium, Calcium, Eisen)
- Why is it important? Minerals may need to be taken in larger amounts, requiring more fillers in tablets or powders. Inferior fillers could inhibit absorption.
- Recommended fillers: Microcrystalline cellulose and acacia fiber
- What to look out for Look out for artificial colors or magnesium stearate in high amounts.

Antioxidants (e.g. Curcumin, Resveratrol, Coenzym Q10)
- Why is it important? Antioxidants are often poorly bioavailable and require appropriate fillers to improve their absorption.
- Recommended bulking agents: MCT oil, lecithin (for better absorption).
- What to look out for Cheap fillers such as soybean oil or unnecessary binders could limit the effectiveness.
Proteinpulver und Aminosäuren
- Why is it important Protein powders are consumed in large quantities, and low-quality fillers could affect long-term health.
- Recommended fillers: Natural thickeners such as guar gum or flaxseed meal.
- What to look out for Watch out for maltodextrin, which is often used as a filler - but can have a negative impact on blood sugar levels.
Kinder- und Schwangerschaftspräparate
- Why is it important These target groups have particularly sensitive systems, and allergenic or questionable additives should be avoided at all costs.
- Recommended fillers: Acacia fiber, olive oil, rice flour.
- What to look out for Avoid additives such as titanium dioxide, artificial sweeteners or colorants.
Multivitaminpräparate
- Why is it important Multivitamins often contain many ingredients and require fillers to stabilize the formulation.
- Recommended fillers: Microcrystalline cellulose, acacia fiber, guar gum.
- What to look out for Avoid products with unnecessary colorants or artificial preservatives.
What to look out for when buying supplements
The quality of the fillers can make the difference between a high-quality and a low-quality dietary supplement. You can pay particular attention to this:
- Check the ingredient list: Fillers such as acacia fiber, MCT oil or guar gum are natural and safe alternatives to synthetic substances such as magnesium stearate.
- Prefer quality label products: Products that do not contain unnecessary additives are often of higher quality.
- Avoid allergens: Watch out for possible allergens such as soy or gluten.
- Manufacturer transparency: Companies that disclose their ingredients and pay attention to quality are more trustworthy. Also look out for regular laboratory certificates from independent institutes.
- Use prebiotic benefits: Fillers such as acacia fiber or guar gum offer additional health benefits, especially for gut health.
- Form and capsule shell: The packaging of the ingredients is also crucial in order to reach the right place in the body. Pay attention to the quality of the shape and capsule shell
Fazit
In summary, a close look at the ingredients list will help you choose a product that is not only safe, but also optimal for your health and longevity goals. Because what we eat every day has a lasting impact on our health. Take your time to choose the right product and rely on certificates that confirm the quality and testing.