Figuring out what vitamins and minerals you should take can be a challenge, but figuring out when is the best time to take your vitamins is another story. Do you take them upon waking? With meals? Before bed? Once a day? Twice a day?
When you take your vitamins can be a primary factor that determines how effective your supplements are. If you’re not absorbing your nutrients, your body can’t utilize them.
So, we’re breaking down the ins and outs of supplementing with one of the most undervalued and under-consumed vitamins out there—vitamin D—and when the ideal time to take it is.
Hint: If you want to truly benefit from the sunshine vitamin, there’s one easy (but super important) key you need to know about.
What Is Vitamin D + 5 Benefits Of Taking It
Commonly referred to as the sunshine vitamin, vitamin D is a fat-soluble pro-hormone produced when UVB rays from the sun hit the skin. Despite being easy to obtain, it’s estimated that more than 50% of the population—that translates to roughly one billion people—are deficient in vitamin D 1.
The pandemic of low vitamin D status is mainly the result of lifestyle factors that limit sun exposure, but it can also result from inadequate dietary intake, malabsorption, or biological factors that reduce synthesis in the skin.
Vitamin D receptors (VDR) are present in almost all tissues and cells in the human body, exhibiting various biological actions ranging from immune support and insulin production, to mood regulation and bone health.
Research also suggests that endogenous production of vitamin D3 (1,25(OH)2D) may regulate more than 200 genes that facilitate many of the health benefits linked to vitamin D 2.
While there’s no end to the benefits that sufficient intake of vitamin D has on the body, we’re narrowing it down to five key benefits:
- Stronger bones: One of the most essential and notable roles of vitamin D is in calcium and phosphate metabolism, which is crucial for maintaining bone integrity and strength throughout the lifespan.
- Healthier immune system: Adequate vitamin D levels are required to support both the adaptive and innate branches of the immune system, and low levels have been linked to an increased risk of autoimmune conditions 3, 4.
- Better mood: Vitamin D receptors are present in areas of the brain responsible for regulating mood, but vitamin D is also involved in the production of serotonin, the “happy hormone” 5, 6.
- Less inflammation: In conjunction with its role in immune function, vitamin D is also involved in regulating levels of inflammation via controlling the production of inflammatory cytokines and inhibiting the proliferation of pro-inflammatory cells 7.
- Better glucose regulation: If you struggle with glucose and insulin imbalances, vitamin D can help! It plays a key role in glucose homeostasis by stimulating the release of insulin from pancreatic B-cells 8.
Fat-Soluble vs. Water-Soluble Vitamins
When considering the timing of your supplements, it’s key to look at how the vitamin is absorbed. Whether it’s water-soluble or fat-soluble will dictate if you should consume your vitamins with a meal or whether you can consume them on an empty stomach. However, there are, of course, exceptions to the rule.
Water-soluble vitamins, as the name suggests, are those that dissolve in water and easily enter the bloodstream. They play major roles in supporting normal metabolic, energy, differentiation, and growth status of cells, and because humans cannot synthesize water-soluble vitamins (except for minimal endogenous synthesis of niacin, vitamin B3), they must be obtained from exogenous sources 9.
As such, levels of these micronutrients depend on adequate absorption in the intestine. Interference with absorption, which happens under various conditions, can lead to deficiency and resulting clinical abnormalities. Excess water-soluble nutrients do not pose a toxicity threat, as they are excreted in urine.
The water-soluble vitamins include:
- Vitamin C
- B vitamins (B1, B2, B3, B5, B6, B7, B7, B12)
Fat-soluble vitamins, on the other hand, cannot be absorbed directly into the bloodstream. Rather, they are absorbed into lacteals in the small intestine via chylomicrons, transported through the lymphatic system, and then released into the bloodstream and travel through systemic circulation 10.
Unlike water-soluble vitamins, fat-soluble vitamins are stored in the body when they are not in use. Typically, they are stored in the liver and fat tissues, so excessive intake of the fat-soluble vitamins can lead to their accumulation in the body and a state known as hypervitaminosis due to delayed elimination rate 11.
The fat-soluble vitamins include:
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
Should You Take Vitamin D On An Empty Stomach?
While you can take vitamin D on an empty stomach, it may not be the best idea if you want to maximize absorption. Because vitamin D is a fat-soluble vitamin, it requires sufficient dietary fat for absorption and utilization.
That means that if you’re taking a vitamin D3 supplement, you want to ensure it’s emulsified in a fat source; otherwise, consume it alongside a healthy fat source like olive oil, avocado, coconut, or nuts and seeds.
A 2014 study published in the Journal of the Academy of Nutrition and Dietetics sought to investigate how the absorption of vitamin D3 is influenced by diet 12.
They found that D3 absorption is greater when taken with a meal containing fat than with a fat-free meal, and absorption is enhanced when the meal contains a higher ratio of monounsaturated-to-polyunsaturated fatty acids (MUFA:PUFA).
What’s more, they found that absorption was a whopping 32% more in subjects consuming fat alongside supplementation, but absorption levels didn’t differ dramatically between the low MUFA and PUFA groups.
There’s more. Another similar study of 17 individuals supplementing vitamin D with the largest meal of the day found, on average, a 57% increase in vitamin D3 serum concentrations compared to those who took it on an empty stomach or with a small meal 13.
Long story short, fat-soluble vitamins should be consumed alongside a meal with adequate dietary fat to maximize absorption and the subsequent benefits.
If you’re not consuming enough fat or your supplement isn’t emulsified with fat, chances are you’re not absorbing nearly as much as you think, and you run with risk of eventually coming face-to-face with a vitamin D deficiency. So, remember, when it comes to the fat-soluble four, vitamin D is your friend!
- R Nair, A Vitamin D: The “sunshine” vitamin.J Pharmacol Pharmacother. 2012;3(2):118-126.
- TJ Wang, MJ Pencina, SL Booth, et al. Vitamin D deficiency and risk of cardiovascular disease. 2008;117(4):503-511.
- M Hewison. Vitamin D and Innate and Adaptive Immunity. Vitamins & Hormones. 2011; 86:23-62.
- KL Munger, LI Levin, BW Hollis, NS Howard, A Ascherio. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. 2006;296(23):2832-2838.
- DW Eyles, S Smith, R Kinobe, M Hewison, JJ McGrath. Distribution of the vitamin D receptor and 1 alpha-hydroxylase in human brain.J Chem Neuroanat. 2005;29(1):21-30.
- RP Patrick, BN Ames. Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar disorder, schizophrenia, and impulsive behavior. FASEB J. 2015;29(6):2207-2222.
- K Yin, DK Agrawal. Vitamin D and inflammatory diseases.J Inflamm Res. 2014;7:69-87.
- E Yousefi Rad, M Djalali, F Koohdani, et al. The Effects of Vitamin D Supplementation on Glucose Control and Insulin Resistance in Patients with Diabetes Type 2: A Randomized Clinical Trial Study.Iran J Public Health. 2014;43(12):1651-1656.
- HM Said. Intestinal absorption of water-soluble vitamins in health and disease.Biochem J. 2011;437(3):357-372.
- N Escobedo, G Oliver. The Lymphatic Vasculature: Its Role in Adipose Metabolism and Obesity.Cell Metab. 2017;26(4):598-609.
- P Ravisankar, AA Reddy, B Nagalakshmi, O Sai Koushik, B Vijaya Kumar, P Sai Anvith. The Comprehensive Review on Fat Soluble Vitamins. IOSR Journal Of Pharmacy. 2015; 5(11):12-28.
- B Dawson-Hughes, SS Harris, AH Lichtenstein, G Dolnikowski, NJ Palermo, H Rasmussen. Dietary fat increases vitamin D-3 absorption. J Acad Nutr Diet. 2015;115(2):225-230.
- GB Mulligan, A Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D.J Bone Miner Res. 2010;25(4):928-930.