By Craig Weatherby
Winter brings shorter, darker days … and much less of the sunshine we need to make vitamin D. And lack of sun promotes vitamin D deficiency … which is linked to heightened risk of mood problems, weakened bones, cancer, and heart disease. Further, as part of the body’s “innate” immune system, vitamin D is needed to help fight winter colds, flu, and other respiratory illnesses.
The US RDA is now 600 IU, and the Institute of Medicine recommends maintaining a blood level of 20 to 50 ng/mL to achieve vitamin D “sufficiency”. However, many experts in the field say that we need a blood level of 30 to 100 ng/mL to attain true vitamin D sufficiency (Holick MF et al. 2011; Heaney RP et al. 2011).
To be sure, you can use vitamin D supplements to maintain adequate intake and blood levels. But there’s a tastier way to help ensure adequate vitamin D in winter … by routinely savoring wild salmon and other fatty fish.
Fatty fish fit the vitamin D bill: Sockeye salmon stand out
Certain fish – especially fattier species – ranks as the only substantial food sources of vitamin D … far outranking milk and other D-fortified foods.
And among all foods, wild sockeye salmon rank as the single richest source, ranging from about 400 to 700 IU per 3.5 ounce serving.
Five years ago, a team led by top vitamin D researcher Michael Holick, M.D., Ph.D., of Boston University found that the average vitamin D3 level in wild caught salmon was 988 IU per standard 3.5 oz (100gm) serving, plus or minus 524 IU.
But farmed Atlantic salmon had only about one-quarter as much vitamin D. As they wrote, “In contrast, farmed salmon had approximately 25% of the vitamin D content present in the flesh of wild salmon. The mean [average] concentration in the flesh of farmed salmon was 240 IU [of vitamin] D3 plus or minus 108 IU.” (Lu Z et al. 2007)
(See “Wild Salmon Affirmed as Top Vitamin D Source”.)
Seven years ago, we commissioned lab tests to determine the vitamin D levels of some of our most popular seafood products … with rewarding results:
* Analysis conducted in June 2005 by Covance Laboratories, Inc. (It is not clear why the result for 6 oz of sardines was not much higher than the result for 3.5 oz.) Click here to view a graph of our full test results.
As you can see, wild Alaskan salmon – especially sockeye – and Pacific albacore tuna rank as the very best foods for preserving healthy vitamin D levels. And even though they rank below salmon and tuna, our sardines, mackerel, sablefish, and halibut still top all other food sources of vitamin D … including D-fortified milk and dairy foods. Better yet, all of these fish are also rich in protein and mood-supporting omega-3s.
Our test results vary from these figures, gleaned from the USDA Nutrient Database. Why would that be? As Dr. Holick’s team found, levels of vitamin and omega-3s in wild fish can vary widely … likely due to seasonal, geographic, dietary, and genetic factors:
*N/A = no data provided by USDA.
Heaney RP, Holick MF. Why the IOM recommendations for vitamin D are deficient. J Bone Miner Res. 2011 Mar;26(3):455-7. doi: 10.1002/jbmr.328.
Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM; Endocrine Society. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30. Epub 2011 Jun 6. Erratum in: J Clin Endocrinol Metab. 2011 Dec;96(12):3908.
Lu Z, Chen TC, Zhang A, Persons KS, Kohn N, Berkowitz R, Martinello S, Holick MF. An evaluation of the vitamin D(3) content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D? J Steroid Biochem Mol Biol. 2007 Jan 29; [Epub ahead of print] doi:10.1016/j.jsbmb.2006.12.010