Chrononutrition: Is There a “Best Time” to Take Nutritional Supplements?

By Melissa Blake, ND

Our bodies have an amazing natural ability of keeping to a daily schedule via an internal 24-hour master clock.1 This clock contributes to the patterns, also known as circadian rhythms, of many biological activities including sleep-wake cycles, eating patterns, and hormone function.1

Finding ways to support and balance this clock, along with the many systems it regulates, may offer a novel way to optimize health. One way to optimize is through diet timing.

The circadian diet as a way of eating takes into account not only what we eat, but when.2 It is an approach to eating that synchronizes food intake around our biological clocks, emphasizing eating in sync with the body’s natural tendencies and instincts. This means eating during daylight hours or hours when we are naturally more active. Eating in this way can help support circadian rhythms and contribute to overall health and wellness.2

As diets and terms including intermittent fasting, circadian diet, and time-restricted eating gain popularity, the question may arise as to whether the principle on which this “circadian approach” applies to other aspects of nutrition, including supplementation.

5 common supplements

Although there’s still much to learn about optimal timing for both food and supplements, current evidence suggests it may play a role.3 Here are a few general guidelines for five common supplements to help you add the extra layer of timing and optimize your plan:

B complex

B vitamins are often recommended to support healthy energy and mood.4 There is some evidence that taking B vitamins before bed can have a negative effect on sleep quality.5 Consider taking any B vitamins, including a B complex, earlier in the day with food.

Fish oil

The most common complaints I hear about fish oil are burping or nausea. Taking fish oil supplements with food, divided into two doses, may help reduce these harmless yet annoying side effects.


Magnesium is an essential micronutrient that plays a role in hundreds of reactions in the body.6

Due to the overall benefits of magnesium supplementation, consistency is more important than any timing in this case. Known for muscle relaxation and improved sleep, taking magnesium before bed may enhance those benefits in some people.7 Others may notice digestive issues and may choose to take with food.


Any recommendation related to probiotic supplementation should be based on the specific strain; however, much of this detailed evidence does not yet exist.  Meal timing has more or less of an impact on probiotics depending on the strain, the dose, delivery method, etc.8 The consensus, however, is to take probiotics 30 minutes before or during a meal versus after eating.9 Another guideline is to space probiotics away from antibiotic medications by two hours to reduce interaction.

Vitamin D

Along with vitamins A, E, and K, vitamin D is a fat-soluble vitamin that is better absorbed when taken with a fat-containing meal (ex. fatty fish, avocado, olive oil, cheese, eggs).10 Although we do not have substantial evidence to support specific timing, it may make sense to take vitamin D supplements in the morning with breakfast to mimic the timing of exposure to natural sunlight.


As we continue to learn about specific supplements and optimal timing, consider that the best timing is the one you can stick with. You cannot benefit from a supplement you do not take. The most important thing is to take your supplements at a time that is convenient for you so you can be consistent.

Work with a knowledgeable healthcare provider to determine the optimal plan for you that includes quality, quantity, and timing.


  1. Rosenwasser AM et al. Sleep Med Clin. 2015;10(4):403-412.
  2. Challet E. Nat Rev Endocrinol. 2019;15(7):393-405. 
  3. Oike H et al. Curr Nutr Rep. 2014;3(3):204-212.
  4. Young LM et al. Nutrients. 2019;11(9):2232.
  5. Aspy DJ et al. Percept Mot Skills. 2018;125(3):451-462.
  6. Rosanoff A et al. Adv Nutr. 2016;7(1):25-43.
  7. Altura BM et al. Med Hypotheses. 2001;57(6):705-713.
  8. Pot B et al. Eur J Med Res. 2021;26(1):40.
  9. Tompkins TA et al. Benef Microbes. 2011;2(4):295-303.
  10. Dominguez LJ et al. Metabolites. 2021;11(4):255.
Melissa Blake, ND
Melissa Blake, ND is the Manager of Curriculum Development at Metagenics. Dr. Blake completed her pre-medical studies at Dalhousie University in Halifax, Nova Scotia, and obtained her naturopathic medical training from the Canadian College of Naturopathic Medicine. Dr. Blake has over 10 years of clinical experience, specializing in the integrative and functional management of chronic health issues.

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