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  • 2019

Chrono-nutrition: Personalizing Which Supplements to Take and When

Published on

28 May 2019

You’re probably familiar with biological clocks – the circadian rhythm that sends out chemical signals at certain times of the day to help you wake, sleep and do other activities. Well, the body also has a food clock—in that the body wants to sync food consumption with chemical reactions in the body. Studies in animals and humans find that eating out of sync with this clock is associated with weight gain, chronic disease and premature aging 1. To override that system, you can eat in a way – earlier, not later – that aligns food patterns with your internal clock. This concept is chrono-nutrition. 

How to synchronize the body’s systems

Research suggests that a few nudges to regular eating habits will help synchronize the body’s internal systems. Most importantly, it means two things:

  • Limit eating to when the sun shines—about a 12-hour window or better yet, shorter. That means cutting back on night-time refrigerator raids. 
  • Eat more in the morning and midday and less later on. The body works best if you pre-load your calories, rather than saving them until the end of the day, which is what many of us do. 

Vitamin supplements

In an ideal world, food would provide all the vitamins, minerals, micro- and macronutrients needed to power the body. But research shows that when it comes to the recommended dietary allowance (RDA) of nutrients, 99.9 percent of people fail to take in 100 percent of what’s recommended and only seven percent of baby boomers get more than 20 percent of the Daily Value of all vitamins and minerals 2.

Chrono-nutrition and supplementing responsibly 

Most experts in the field of longevity promotion, including myself, believe these deficiency numbers fall short of what is optimal for healthy longevity. There are several nutritional supplements that support overall health when taken at the best time of day to help sync the body’s systems.  

Vitamin D3 

Under the conditions experienced by our great, great forefathers, they didn’t need to get active vitamin D from food. Rather, their bodies made it from sunlight. Dark skin protects against intense, equatorial sun, while allowing for adequate vitamin D production in skin to foster healthy growth and development. In these eras, the level of vitamin D in the body, based on what we know about levels achieved by populations living outdoors with frequent sun exposure, was in the range of 50 to 110 mg/dL.  

In populations that live north of the line between Atlanta and Los Angeles, 67 to 93 percent of the population is vitamin-D deficient—with a blood level below 30ng/ml. The sun rays that reach earth north of that line between October 1 and April 15 do not have enough energy in general to convert precursors to active vitamin D. Even in the southern parts of the U.S., more than 50 percent of people are deficient in vitamin D at a level of 30ng/ml (or mg/dL). Research shows a blood level of 35ng/ml helps protect arteries from the effects of aging, is associated with less incidence of dementia and protection against erectile dysfunction 3-12.  After 50 years of age, the absorption of vitamin D by the body has been found to be irregular. Therefore, I advise people who are over the age of 50 to get a blood test annually to find out what supplementation is needed to reach a level of 50 to 80ng/ml of vitamin D. Until then, speak to your health care practitioner about taking 2,000 IU daily. 


In terms of chrono-nutrition, I recommend slipping a multi-vitamin in half, so one half is taken in the morning (a.m.) and the other half is taken in the afternoon (p.m.). By splitting the multi-vitamin in half, it helps keep nutrient blood levels constant in the body as you urinate the water-soluble components in under 16 hours, which you likely notice in the change of color in your urine. 

Look for a multi-vitamin with nutrient levels close to the recommended dietary allowance (RDA) since a spike in one nutrient can throw off the working relationship between nutrients and can do more harm than good. Be sure none of your other supplements have additional amounts of these vitamins or minerals or you may experience toxicity from increased levels of one nutrient. 

Calcium citrate and magnesium  

Calcium supports your health in many ways, including building bone strength, helping nerve functioning, and reducing the risk of certain cancers 13,14. Generally, people get about half the daily calcium they need (total in a day recommended is ~1,200mg) from food alone, so take a 600mg supplement 15. It usually is not included in appreciable amounts in a multi-vitamin, so that is why an additional supplement may be needed. Magnesium at 300mg a day helps counteract the constipation complication associated with calcium. The ratio of the two is important for cancer prevention and nerve functioning so both should be taken daily 16. Magnesium helps regulate muscle and nerve function, blood sugar levels, blood pressure and is important in making protein, bone and healthy DNA 17.

I typically suggest people take magnesium at night as it can help support sleep initiation and maintenance.

DHA omega-3 

DHA is the part of fish oil that is brain food since 97 percent of the omega-3s found in the human brain is made up DHA omega-3. I recommend 900mg of DHA omega-3 daily or eat 12 ounces of salmon or ocean trout a week 18-22, and try taking this nutrient in the morning to support nutrition levels throughout the day. Salmon cakes in the morning are delicious too! 

By coupling eating habits, including when to eat and what to eat, with a dietary supplement regimen that is organized by time of day, the body will optimize key nutrients throughout the day, and throughout the lifespan. 

Follow NUTRI-FACTS on LinkedIn for real-time research news and expert opinions. 


  1. Roizen, M.F. (2019) What to Eat When. Washington, DC, National Geographic.
  2. Ames, B.N. PNAS October 23, 2018 115 (43) 10836-10844; first published October 15, 2018 https://doi.org/10.1073/pnas.1809045115
  3. Giovannucci E. J. Natl Cancer Inst. 2006;98:451.
  4. Lappe J. M. et al. Am J Clin Nutr 2007; 85:1586.
  5. Gorhan E.D. Am J Prev Med 2007;32:210.
  6. Jenab M. et al. BMJ.2010;340.
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  9. Mokry L.E. et al. Neurology 2016 Dec 13;87(24):2567-2574.
  10. Autier P. et al. Arch Intern Med. 2007;167:1730.
  11. Melamed et al. Arch Intern Med. 2008;168:1629-1637.
  12. Afzal S. et al. BMJ. 2014; 346:g6330.
  13. Bodtock RM Amer J Epid 1999;149: 151-161.
  14. Lappe JM et al. J Clin Nutr. 2007;85:1586.
  15. Cancer Epid Biomark Prev 2013.
  16. Dai Q. et al. BMJ  2012; e002111.
  17. https://ods.od.nih.gov/factsheets/Magnesium-Consumer/
  18. Jacques et al. Cord Level of DHA Associated Improved Visual Function 11.3 Yrs Later J Peds 2011.
  19. Hoffman Prostaglandins, Leuko & EFA, 2009.
  20. Stough, Neurob of Aging, 2012. 
  21. Chiu, BJOpth, 2009. 
  22. Ho, Arch Opth, 2011.

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