Vitamin + Supplement Tips: Absorption for Maximum Levels

For best absorption, is it better to take vitamin D3 and omega-3 fatty acids alone or in combination with other vitamins or supplements? (For example, vitamin D3 is often combined with calcium and/or magnesium. Is this the best way to take this supplement?)

Clearly, the best way to “absorb” vitamin D3 is to step into the sunlight, which stimulates the production of this hormone/vitamin in your skin.  However, due to the known risks of sun exposure (e.g., skin cancer and autoimmune photosensitivity), it’s probably safer for individuals with autoimmune diseases to boost their vitamin D levels with supplements.  Vitamin D is a fat-soluble nutrient, so it’s better-absorbed in a lipid-rich environment.  Thus, taking vitamin D3 along with your fish oil might be the ideal way to take both supplements.  According to Dr. Elson Haas, author of Staying Healthy with Nutrition, the Complete Guide to Diet and Nutritional Medicine, vitamin D absorption may also be improved in the presence of vitamin A, making cod liver oil another good source of vitamin D3.  (Keep in mind that high doses of synthetic vitamin A [e.g., retinyl palmitate], as well as vitamin A from animal sources [retinol], could lead to toxicity.)  Vitamin D is frequently combined with calcium and magnesium to improve the absorption of both minerals.  (By the way, the ideal calcium-to-magnesium ratio in such supplements is 2:1.) In some nutritionists’ view, consuming these three nutrients together is the ideal way to support bone health.*

Are vitamins, minerals, and other supplements absorbed better if they’re taken with food?

Ideally, all of the vitamins, minerals, and phytonutrients we require for optimal health would be obtained from dietary sources.  Unfortunately, the typical American diet falls short of supplying these needs—in large part due to industrial agricultural practices and leaching of minerals from soils—so supplementation appears to be necessary if we hope to obtain sufficient amounts of some essential nutrients.  In most cases, vitamins and supplements are best taken with food because that’s the way our bodies are accustomed to obtaining them.  Indeed, some supplements, such as calcium carbonate, are better absorbed in an acidic environment, so most nutritionists recommend that it be consumed with a meal, which stimulates gastric acid secretion.  Similarly, many forms of iron are best taken with acidic “chasers,” such as vitamin C.  In contrast, calcium citrate and the various calcium chelates may be better absorbed on an empty stomach.  Therefore, it’s important to investigate the best way to take each of your supplements.

Does absorption improve if vitamins and supplements are spread throughout the day?

Certain supplements should be split up, as your intestinal capacity for absorbing them is limited.  For example, your intestine can absorb about 40 grams of protein at one sitting, so if you’re taking a protein powder supplement to boost your weight or improve muscular function, you may need to split it into multiple doses to maximize its benefits.  Likewise, your intestine can only handle about 600 mg of calcium at one time.  Since many doctors advise menopausal women to take 1,200 to 1,500 mg of calcium every day to prevent osteoporosis, you may need to divide your calcium into two or even three portions.  This will not only improve overall absorption; it might even ameliorate some of the cardiovascular risks associated with calcium supplementation (see * below).  If your doctor recommends large doses of omega-3 fatty acids (say, 3,000 mg daily to help with rheumatoid arthritis), taking it all together could lead to “fish burps” and/or diarrhea; dividing your fish oil into several portions would alleviate some of the GI side effects of higher omega-3 intake (Handy tip: refrigerate or freeze your fish oil supplement to cut down on fishy burps.)  Once again, check with your health care provider or your nutritionist to determine the best way to take a given supplement.

Questions for your doctor:

  • I’m taking vitamin D. Is it better to take a dry formulation or an oil-based formulation, and should I take it with meals or on an empty stomach?
  • There’s been some research that shows calcium supplementation could increase my risk for a heart attack. Should I keep taking my calcium?

* A study published in the April 2011 issue of British Medical Journal—and recently voiced in the lay press—suggested that calcium supplementation “modestly increases the risk of cardiovascular events” (especially heart attacks).  While this study is far from conclusive, there may be some changes in the guidelines for calcium supplementation in the not-too-distant future.

MJ Bolland, et al. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women’s Health Initiative limited access dataset and meta-analysis. BMJ. April 2011
Staying Healthy with Nutrition, the Complete Guide to Diet and Nutritional Medicine: Vitamin D (Calciferol). Elson M. Haas, MD. Celestial Arts, 2006


About the Author
Steve Christensen, MD – “Doom” to his close friends – was trained at the University of Utah School of Medicine. Since his premature retirement from medicine in 2003, Dr. Christensen has expanded his knowledge of alternative medicine: he is a certified herbalist; he has dabbled at the edges of Ayurvedism, shared ideas with Chinese physicians, rubbed shoulders with Native American healers and contemplated the healing powers of channeled energy.


This post contains opinions of the author. is not a medical practice and does not provide medical advice, diagnosis, or treatment.  It is your responsibility to seek diagnosis, treatment, and advice from qualified providers based on your condition and particular circumstances.  Camino Real Ventures, Inc., the company that makes available to you, does not endorse nor recommend any products, practices, treatment methods, tests, physicians, service providers, procedures, clinical trials, opinions or information available on this website.  Your use of the website is subject to our Terms of Use and Privacy Policy



  1. Hmm is anyone else encountering problems with the pictures
    on this blog loading? I’m trying to figure out if its a problem on my end or if it’s the blog.
    Any feed-back would be greatly appreciated.

    • Katie Cleary says:

      Hi Bette,
      Sorry you’re having issues – I’m not sure what the problem is. There isn’t a photo associated with this blog post, but there are photos with most other posts. Let me know what browser you’re using and other posts where you’re having trouble and I will look into it. Thanks for reading!

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