Edoardo Mazzocchi

4 Min. Lesezeit

“Better in the morning or the evening? Before or after training? On an empty stomach or with meals?” – these are some of the most common questions about food supplements. And the answer, as so often in nutrition, is less clear-cut than we would like: it depends.

Active Lifestyle Energy, Sleep & Metabolism
Key points at a glance
  • There is no generally valid time of intake for food supplements.
  • For creatine and beta-alanine, what counts above all is regular intake over a longer period.
  • For iron, vitamin D and omega-3, what the supplement is taken with can be more important.
  • For caffeine, nitrates and sodium bicarbonate, timing can be decisive for the desired acute effect.
  • Magnesium does not have to be taken in the evening as a rule – the current body of research does not allow such a general recommendation.
  • First come the requirement, the product, the dosage and the formulation. Only then should the time be set.

When regularity is what matters most

Creatine is probably the best example. For years, the question “before or after training?” was debated. The available evidence does not, however, allow a significant and consistent advantage to be attributed to either time of intake. To increase creatine stores in the musculature, what matters above all is taking creatine regularly over a longer period. A study that directly compared intake immediately before and after training also found no differences in the adaptations of strength and muscle hypertrophy.1

A similar idea applies to beta-alanine. It is not the classic supplement that you take twenty minutes before training and expect an immediate effect from: it serves to increase the carnosine concentration in the musculature over time. A 2025 systematic review emphasises above all the importance of the cumulative dosage and of splitting it into several intakes across the day – also to limit paraesthesias.2

If, in these cases, it helps to take the supplement at breakfast so as to remember it every day, you have already found a very good “timing”.

Sometimes what matters more is what we take supplements with

Iron is a good example of why focusing solely on the time can be misleading. Absorption here is influenced by various components of food. Tea and coffee, for instance, contain polyphenols that can reduce the absorption of non-haem iron. Larger amounts of calcium taken at the same time can also impair iron absorption.3 In this case, it can be more important to organise intake sensibly in relation to meals and drinks than merely to ask “8 a.m. or 8 p.m.?”.

With vitamin D, too, a clarification is worthwhile. It is a fat-soluble vitamin, and studies show that fat during a meal can promote its absorption.4 This does not mean, however, that avocado, nuts or oil have to be added every time a capsule is taken: many formulations are already in an oily matrix, and vitamin D is absorbed even without a particularly fat-rich meal. The formulation of the product plays a role.

The situation is similar with omega-3 fatty acids. Taking them together with a meal can increase the bioavailability of some formulations and is often also a practical way to improve gastrointestinal tolerability. Taking food supplements is therefore not only about the time of day – depending on the nutrient, meals, other substances and the specific form of the supplement can be of greater importance.

When the time of intake really matters

When an acute effect on performance is to be achieved, the picture is different. Here the timing can genuinely become part of the strategy – as the following examples show.

Caffeine

Caffeine is the most obvious example. For capsules and tablets, intake about 30 to 60 minutes before training is the best studied. The optimal time depends, however, on the formulation – a caffeinated chewing gum, for example, can show markedly faster kinetics. A 2025 network meta-analysis confirms an effect of caffeine on performance in time-trial tests and at the same time highlights the large individual variability of the response.5

30–60 minutes

before training is the best-studied time of intake for caffeine in capsule or tablet form. Depending on the formulation (e.g. chewing gum) it can differ.5

Source: Xue et al., Nutrients 2025

A further point is important particularly for athletes: one should assess not only when caffeine improves training, but also when it may worsen what comes afterwards. Meta-analyses show that intake too close to the evening can impair sleep duration and sleep quality. Improving a training session and sacrificing recovery for it is not necessarily a good strategy.

Nitrates

Nitrates, too, such as those contained for example in beetroot concentrates, require a strategy. In acute protocols they are generally used a few hours beforehand, so that enough time remains for the conversion of nitrate to nitrite and then to nitric oxide. A large 2025 umbrella review that included 20 meta-analyses shows benefits for some performance parameters, but also inconsistent results.6 A good example of why “more supplements” does not automatically mean “more performance”.

Sodium bicarbonate

This becomes even clearer with sodium bicarbonate. The ISSN recommendations generally provide for intake 60 to 180 minutes before training. Here, however, the individual response of the gastrointestinal tract becomes decisive.7 Bloating, nausea and intestinal complaints can completely negate the possible performance-enhancing effect. Dosage and timing should therefore be tested beforehand and not improvised for the first time on competition day.

60–180 minutes

before exertion is the usual window the ISSN provides for a single dose of sodium bicarbonate – the individual gastrointestinal tolerability is decisive here.7

Source: Grgic et al., ISSN Position Stand 2021

And magnesium? Always in the evening?

This is one of the most frequently repeated pieces of advice on the internet and on social media – and a good example of how a simple rule can become too simple. There are various forms of magnesium that differ in bioavailability and tolerability; which one is suitable in an individual case we set out in the article: Which magnesium is the best?. In addition, the reason for taking it can be completely different: compensating for an inadequate intake, aiming for a particular clinical effect, or building magnesium into an evening routine are different situations.

Magnesium is often associated with sleep, and some studies are interesting. The systematic reviews do not, however, so far allow the conclusion that magnesium should be taken in the evening as a rule, or that intake in the evening alone increases its efficacy.8 For minerals such as magnesium, too, the following therefore applies: it is not the time alone that determines the benefit of a supplement. How much magnesium per day is generally sensible you can read in the article: How much magnesium per day?.

Conclusion

The probably most helpful answer is: before choosing the time, you should understand the supplement. For some products such as creatine and beta-alanine, what makes the difference above all is regularity over a longer period. For others such as iron, vitamin D and omega-3, the formulation, meals and possible interactions become important. For substances with an acute effect such as caffeine, nitrates or bicarbonate, on the other hand, timing genuinely becomes part of the strategy.

Routines along the lines of “five capsules in the morning, three in the evening” are therefore not advisable when there is no rational justification for them. First comes the requirement. Then the product, the dose and the formulation. And only then the time. Because a food supplement does not work better just because the right alarm has been set.

FAQs about When should you take food supplements?
What is the best time of day to take food supplements?

There is no universally valid time of day. For some supplements what counts above all is regular intake, for others meals, drinks or the formulation are more important. For substances with an acute effect, by contrast, the precise time of intake can play a greater role.

Should food supplements be taken on an empty stomach or with a meal?

That depends on the particular supplement. With iron, for example, components of food and drinks can influence absorption. With vitamin D and certain omega-3 formulations, by contrast, intake together with a meal can be relevant.

Does the dosage form play a role in the time of intake?

Yes, in some cases. With caffeine, for example, the rate of absorption can differ between capsules or tablets and a caffeinated chewing gum. With vitamin D, too, the formulation plays a role, as some products are already in an oily matrix.

Should creatine be taken before or after training?

The available evidence shows no consistent advantage of intake immediately before or after training. To increase the creatine stores in the musculature, what is decisive above all is regular intake over a longer period.

What should be considered when taking iron?

With iron, what it is taken with can be more important than what time. Tea and coffee, because of their polyphenols, can reduce the absorption of non-haem iron. Larger amounts of calcium can also influence absorption when taken at the same time.

Should vitamin D be taken with a meal?

Vitamin D is fat-soluble. The presence of fat during a meal can promote its absorption. At the same time, the formulation of the supplement plays a role, as many products are already in an oily matrix.

Should magnesium always be taken in the evening?

No. Magnesium is often associated with sleep and an evening intake. The systematic reviews available so far do not, however, allow the conclusion that magnesium should be taken in the evening as a rule, or that evening intake alone increases its efficacy.

Sources
  1. Ribeiro F. et al. (2021): Timing of Creatine Supplementation around Exercise: A Real Concern? Nutrients 13(8):2844 – Shows that no consistent advantage of intake immediately before or after training can be derived from the available data; regular intake over a longer period is decisive.
  2. Ong S.-W. et al. (2025): Dosing strategies for β-alanine supplementation in strength and power performance. J Int Soc Sports Nutr 22(1):2566368 – Emphasises the importance of the cumulative dosage and of splitting it into several intakes across the day, also to limit paraesthesias.
  3. Piskin E. et al. (2022): Iron Absorption: Factors, Limitations, and Improvement Methods. ACS Omega 7(24):20441–20456 – Describes the factors that influence iron absorption, including polyphenols from tea and coffee and larger amounts of calcium.
  4. Silva M.C., Furlanetto T.W. (2018): Intestinal absorption of vitamin D: a systematic review. Nutrition Reviews 76(1):60–76 – Systematic review on the absorption of vitamin D, including the favourable influence of dietary fat.
  5. Xue R. et al. (2025): Effects of Caffeine Dose and Administration Method on Time-Trial Performance: A Systematic Review and Network Meta-Analysis. Nutrients 17(23):3792 – Network meta-analysis on the dose and administration form of caffeine in time-trial tests; highlights the large individual variability of the response.
  6. Poon E.T.C. et al. (2025): Dietary Nitrate Supplementation and Exercise Performance: An Umbrella Review of 20 Published Systematic Reviews with Meta-analyses. Sports Medicine 55(5):1213–1231 – Umbrella review of 20 meta-analyses; shows benefits for some performance parameters, but inconsistent results.
  7. Grgic J. et al. (2021): International Society of Sports Nutrition position stand: sodium bicarbonate and exercise performance. J Int Soc Sports Nutr 18(1):61 – ISSN position stand; recommends, for single doses, intake 60 to 180 minutes before exertion and emphasises individual gastrointestinal tolerability.
  8. Arab A. et al. (2023): The Role of Magnesium in Sleep Health: a Systematic Review of Available Literature. Biol Trace Elem Res 201(1):121–128 – Systematic review; the evidence does not allow the conclusion that magnesium should be taken in the evening as a rule, or that evening intake alone increases efficacy.
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