{
 "name": "TakeItWhen supplement timing rules",
 "publisher": "TakeItWhen",
 "url": "https://takeitwhen.com/rules.json",
 "generated": "2026-10-31",
 "license": "Free to use and quote with attribution. Please credit \"TakeItWhen\" and link to https://takeitwhen.com (or the rule's guide_url).",
 "disclaimer": "General information, not medical advice. If you take a prescription medicine, ask your doctor or pharmacist.",
 "grades": {
  "strong": "consistent human trials",
  "moderate": "some human trials",
  "weak": "limited or indirect evidence",
  "myth": "evidence says no"
 },
 "scope": "Only rules that have a public guide on takeitwhen.com. The full personalised schedule (more supplements and interactions) is free in the app after joining the newsletter.",
 "count": 14,
 "rules": [
  {
   "id": "when-to-take-magnesium",
   "supplements": [
    "Magnesium"
   ],
   "question": "When is the best time to take magnesium?",
   "guidance": "Any time of day you will remember. The popular rule that magnesium must be taken at night has weak evidence; taking it consistently matters more than the clock. If you also take iron, keep them apart.",
   "grade": "weak",
   "sources": [
    {
     "text": "NIH Office of Dietary Supplements, Magnesium fact sheet (ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/)"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/when-to-take-magnesium/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "best-time-to-take-creatine",
   "supplements": [
    "Creatine"
   ],
   "question": "What is the best time to take creatine?",
   "guidance": "Whenever you will take it every day, rest days included. Daily intake is what fills muscle stores (graded moderate). Before vs after training made no reliable difference in trials (graded weak), so pick the time you will not forget.",
   "grade": "moderate",
   "sources": [
    {
     "text": "Dinan 2022, Front Sports Act Living (PMID 36465581)",
     "pmid": "36465581",
     "url": "https://pubmed.ncbi.nlm.nih.gov/36465581/"
    },
    {
     "text": "Hultman 1996, J Appl Physiol (PMID 8828669)",
     "pmid": "8828669",
     "url": "https://pubmed.ncbi.nlm.nih.gov/8828669/"
    },
    {
     "text": "Antonio & Ciccone 2013, J Int Soc Sports Nutr (PMID 23919405)",
     "pmid": "23919405",
     "url": "https://pubmed.ncbi.nlm.nih.gov/23919405/"
    },
    {
     "text": "Candow 2015, Appl Physiol Nutr Metab (PMID 25993883)",
     "pmid": "25993883",
     "url": "https://pubmed.ncbi.nlm.nih.gov/25993883/"
    },
    {
     "text": "Jurado-Castro 2021, Int J Environ Res Public Health (PMID 35010653)",
     "pmid": "35010653",
     "url": "https://pubmed.ncbi.nlm.nih.gov/35010653/"
    },
    {
     "text": "Forbes 2021 (PMID 34610729)",
     "pmid": "34610729",
     "url": "https://pubmed.ncbi.nlm.nih.gov/34610729/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/best-time-to-take-creatine/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "can-you-take-iron-and-calcium-together",
   "supplements": [
    "Iron",
    "Calcium"
   ],
   "question": "Can you take iron and calcium at the same time?",
   "guidance": "Better not. Calcium taken with an iron meal or dose lowers how much iron you absorb (graded strong). Take them at different times of day. The exact 2-hour gap often quoted has not itself been tested.",
   "grade": "strong",
   "sources": [
    {
     "text": "Hallberg 1991, Am J Clin Nutr (PMID 1984335)",
     "pmid": "1984335",
     "url": "https://pubmed.ncbi.nlm.nih.gov/1984335/"
    },
    {
     "text": "Cook 1991, Am J Clin Nutr (PMID 1984334)",
     "pmid": "1984334",
     "url": "https://pubmed.ncbi.nlm.nih.gov/1984334/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/can-you-take-iron-and-calcium-together/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "when-to-take-vitamin-d",
   "supplements": [
    "Vitamin D"
   ],
   "question": "Should you take vitamin D with food?",
   "guidance": "Take it with a meal that has some fat (graded moderate). In 50 older adults, peak vitamin D3 in the blood was 32% higher after a fat-containing meal than a fat-free one. Absorption still happens without fat, and time of day matters less than taking it.",
   "grade": "moderate",
   "sources": [
    {
     "text": "Dawson-Hughes 2015, J Acad Nutr Diet (PMID 25441954, doi:10.1016/j.jand.2014.09.014)",
     "pmid": "25441954",
     "url": "https://pubmed.ncbi.nlm.nih.gov/25441954/"
    },
    {
     "text": "Dawson-Hughes 2013, J Bone Miner Res (PMID 23427007, doi:10.1002/jbmr.1896)",
     "pmid": "23427007",
     "url": "https://pubmed.ncbi.nlm.nih.gov/23427007/"
    },
    {
     "text": "Silva & Furlanetto 2018, Nutr Rev (PMID 29025082, doi:10.1093/nutrit/nux034)",
     "pmid": "29025082",
     "url": "https://pubmed.ncbi.nlm.nih.gov/29025082/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/when-to-take-vitamin-d/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "collagen-timing",
   "supplements": [
    "Collagen"
   ],
   "question": "When should you take collagen?",
   "guidance": "Our protocol is marine collagen only: 5 g fasted in the morning, 15 g about 30-60 minutes before training, and an optional dose about an hour before bed. Timing evidence is limited, so every part is graded weak.",
   "grade": "weak",
   "sources": [
    {
     "text": "Shaw 2017, Am J Clin Nutr (PMID 27852613)",
     "pmid": "27852613",
     "url": "https://pubmed.ncbi.nlm.nih.gov/27852613/"
    },
    {
     "text": "Thomas 2024 (sleep study, industry-linked)"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/collagen-timing/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "fish-oil-morning-or-night",
   "supplements": [
    "Fish oil (omega-3)"
   ],
   "question": "Should you take fish oil in the morning or at night?",
   "guidance": "The time of day matters less than the meal. Fish oil is absorbed better with a meal that contains fat, especially the common ethyl-ester form (graded moderate), so take it with your fattiest meal, morning or night.",
   "grade": "moderate",
   "sources": [
    {
     "text": "Lawson & Hughes 1988, Biochem Biophys Res Commun (PMID 2847723)",
     "pmid": "2847723",
     "url": "https://pubmed.ncbi.nlm.nih.gov/2847723/"
    },
    {
     "text": "Davidson 2012, J Clin Lipidol (PMID 23312053)",
     "pmid": "23312053",
     "url": "https://pubmed.ncbi.nlm.nih.gov/23312053/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/fish-oil-morning-or-night/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "zinc-and-iron",
   "supplements": [
    "Zinc",
    "Iron"
   ],
   "question": "Can you take zinc and iron together?",
   "guidance": "Keep them apart where you can, as a precaution (graded weak). Iron reduced zinc absorption in solution, but not clearly when taken with meals.",
   "grade": "weak",
   "sources": [
    {
     "text": "Whittaker 1998, Am J Clin Nutr (review)"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/zinc-and-iron/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "ashwagandha-timing",
   "supplements": [
    "Ashwagandha"
   ],
   "question": "When should you take ashwagandha?",
   "guidance": "Follow your product label. Timing evidence for ashwagandha is limited, so no time of day is proven better (graded weak). If you take a prescription medicine, check with your doctor or pharmacist first.",
   "grade": "weak",
   "sources": [
    {
     "text": "NIH Office of Dietary Supplements, Ashwagandha fact sheet (ods.od.nih.gov/factsheets/Ashwagandha-HealthProfessional/)"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/ashwagandha-timing/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "coffee-and-iron",
   "supplements": [
    "Iron"
   ],
   "question": "How long after coffee can I take iron?",
   "guidance": "Don't have coffee or tea with iron or in the 1-2 hours after it: that cuts how much iron you absorb (graded strong). Coffee at least 1 hour before seems fine, but that rests on one 1983 study that used meals, not pills (graded weak). Coffee with a meal cut iron absorption by 39% in that study.",
   "grade": "strong",
   "sources": [
    {
     "text": "Morck 1983, Am J Clin Nutr (PMID 6402915, doi:10.1093/ajcn/37.3.416)",
     "pmid": "6402915",
     "url": "https://pubmed.ncbi.nlm.nih.gov/6402915/"
    },
    {
     "text": "von Siebenthal 2023, Am J Hematol (PMID 37357807)",
     "pmid": "37357807",
     "url": "https://pubmed.ncbi.nlm.nih.gov/37357807/"
    },
    {
     "text": "Hallberg & Rossander 1982, Hum Nutr Appl Nutr (PMID 6896705)",
     "pmid": "6896705",
     "url": "https://pubmed.ncbi.nlm.nih.gov/6896705/"
    },
    {
     "text": "Hurrell 1999, Br J Nutr (PMID 10999016)",
     "pmid": "10999016",
     "url": "https://pubmed.ncbi.nlm.nih.gov/10999016/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/coffee-and-iron/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "caffeine-before-bed",
   "supplements": [
    "Caffeine"
   ],
   "question": "How many hours before bed should you stop caffeine?",
   "guidance": "About 9 hours for a regular coffee. In a home study of 12 adults, 400 mg of caffeine (about 4 cups) taken 6 hours before bed still cut sleep by about an hour. A 2023 review of 24 studies suggests stopping a regular coffee about 9 hours before bed, and a pre-workout about 13 hours before (graded moderate).",
   "grade": "moderate",
   "sources": [
    {
     "text": "Drake 2013, J Clin Sleep Med (PMID 24235903)",
     "pmid": "24235903",
     "url": "https://pubmed.ncbi.nlm.nih.gov/24235903/"
    },
    {
     "text": "Gardiner 2023, Sleep Med Rev (PMID 36870101)",
     "pmid": "36870101",
     "url": "https://pubmed.ncbi.nlm.nih.gov/36870101/"
    },
    {
     "text": "Guest 2021, ISSN position stand (PMID 33388079)",
     "pmid": "33388079",
     "url": "https://pubmed.ncbi.nlm.nih.gov/33388079/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/caffeine-before-bed/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "creatine-and-coffee",
   "supplements": [
    "Creatine",
    "Caffeine"
   ],
   "question": "Can you take creatine with coffee?",
   "guidance": "Probably yes. The idea that coffee cancels creatine comes mainly from one small 1996 study using very high loading doses. Later trials are mixed, and a 2016 trial found no difference when creatine was taken with coffee. The evidence is graded weak, so if you want to play it safe during a high-dose loading phase, you could take them at different times of day (a precaution, not something trials have tested). On a normal daily dose, there is no clear reason to skip your coffee.",
   "grade": "weak",
   "sources": [
    {
     "text": "Vandenberghe 1996, J Appl Physiol (PMID 8929583, doi:10.1152/jappl.1996.80.2.452)",
     "pmid": "8929583",
     "url": "https://pubmed.ncbi.nlm.nih.gov/8929583/"
    },
    {
     "text": "Trexler 2016, J Strength Cond Res (PMID 26439785, doi:10.1519/JSC.0000000000001223)",
     "pmid": "26439785",
     "url": "https://pubmed.ncbi.nlm.nih.gov/26439785/"
    },
    {
     "text": "Elosegui 2022, Int J Sport Nutr Exerc Metab (PMID 35016154, doi:10.1123/ijsnem.2021-0262)",
     "pmid": "35016154",
     "url": "https://pubmed.ncbi.nlm.nih.gov/35016154/"
    },
    {
     "text": "Trexler & Smith-Ryan 2015, Int J Sport Nutr Exerc Metab (PMID 26219105, doi:10.1123/ijsnem.2014-0193)",
     "pmid": "26219105",
     "url": "https://pubmed.ncbi.nlm.nih.gov/26219105/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/creatine-and-coffee/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "whey-before-or-after-workout",
   "supplements": [
    "Whey protein"
   ],
   "question": "Should I drink whey protein before or after my workout?",
   "guidance": "Either works. The idea that you must drink your shake within a short window after training is graded myth for healthy adults who eat enough protein. In trials that compared the same protein dose before vs after training, gains in lean mass were the same. Hitting your daily protein total matters more than the clock.",
   "grade": "myth",
   "sources": [
    {
     "text": "Casuso & Goossens 2025, Nutrients (PMID 40647175, doi:10.3390/nu17132070)",
     "pmid": "40647175",
     "url": "https://pubmed.ncbi.nlm.nih.gov/40647175/"
    },
    {
     "text": "Schoenfeld 2017, PeerJ (PMID 28070459, doi:10.7717/peerj.2825)",
     "pmid": "28070459",
     "url": "https://pubmed.ncbi.nlm.nih.gov/28070459/"
    },
    {
     "text": "Morton 2018, Br J Sports Med (PMID 28698222, doi:10.1136/bjsports-2017-097608)",
     "pmid": "28698222",
     "url": "https://pubmed.ncbi.nlm.nih.gov/28698222/"
    },
    {
     "text": "Wirth 2020, J Nutr (PMID 32232404, doi:10.1093/jn/nxaa049)",
     "pmid": "32232404",
     "url": "https://pubmed.ncbi.nlm.nih.gov/32232404/"
    },
    {
     "text": "Klemp 2025, J Int Soc Sports Nutr (PMID 40539259, doi:10.1080/15502783.2025.2519511)",
     "pmid": "40539259",
     "url": "https://pubmed.ncbi.nlm.nih.gov/40539259/"
    },
    {
     "text": "Esmarck 2001, J Physiol (PMID 11507179, doi:10.1111/j.1469-7793.2001.00301.x)",
     "pmid": "11507179",
     "url": "https://pubmed.ncbi.nlm.nih.gov/11507179/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/whey-before-or-after-workout/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "can-magnesium-keep-you-awake",
   "supplements": [
    "Magnesium"
   ],
   "question": "Can magnesium keep you awake at night?",
   "guidance": "There is no good evidence that it does, and no strong evidence that it helps you sleep either. A 2026 review of 12 randomized trials found the effects of magnesium on sleep were inconsistent, and rated the certainty of the evidence low to very low (graded weak). If you notice you sleep worse after taking it in the evening, moving it to earlier in the day is a simple personal test; no trial has compared morning with evening magnesium.",
   "grade": "weak",
   "sources": [
    {
     "text": "Lopresti, Smith & Drummond 2026, J Diet Suppl (PMID 42661485, doi:10.1080/19390211.2026.2719670)",
     "pmid": "42661485",
     "url": "https://pubmed.ncbi.nlm.nih.gov/42661485/"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/can-magnesium-keep-you-awake/",
   "last_updated": "2026-10-31"
  },
  {
   "id": "can-you-take-zinc-and-magnesium-together",
   "supplements": [
    "Magnesium",
    "Zinc"
   ],
   "question": "Can you take zinc and magnesium together?",
   "guidance": "Probably yes at normal doses. The worry comes from one 1994 study in which very high zinc (142 mg a day, far above the 40 mg adult upper limit) lowered magnesium absorption in adult men on a metabolic ward. No trial we found tested ordinary supplement doses taken together, so the evidence is graded weak. If you want to be cautious, you can take them at different times of day. There is no proven best time to take magnesium, so pick a time you will remember.",
   "grade": "weak",
   "sources": [
    {
     "text": "Spencer, Norris & Williams 1994, J Am Coll Nutr (PMID 7836627, doi:10.1080/07315724.1994.10718438)",
     "pmid": "7836627",
     "url": "https://pubmed.ncbi.nlm.nih.gov/7836627/"
    },
    {
     "text": "NIH Office of Dietary Supplements, Zinc fact sheet for health professionals (adult upper limit 40 mg/day)"
    }
   ],
   "guide_url": "https://takeitwhen.com/guides/can-you-take-zinc-and-magnesium-together/",
   "last_updated": "2026-10-31"
  }
 ]
}