By now, most of us have heard of the importance of Vitamin D. Vitamin D plays an important role in the absorption of calcium (see post Getting Enough Calcium On A Dairy-Free Diet), and has the ability to decrease inflammation in the body (1). Vitamin D comes primarily from the sun, but in northern latitudes (37 degrees north) during the winter months, we just can’t get enough (2). While there are some food sources of vitamin D, we actually can’t get enough vitamin D from food alone. The best food source of Vitamin D is oily fish, and while vitamin D foods for vegetarians can be limited there are some steps we can take to ensure we are getting enough.
What Is Vitamin D For
One of the most well-recognized roles of vitamin D is its role in bone health and its ability to increase the absorption of calcium in our bodies. Vegetarian and vegan sources of calcium can be plentiful in a well-balanced diet containing a wide variety of foods – see my post 10 Surprisingly Non-Dairy Sources of Calcium. Vitamin D also has the ability to modulate the immune system and oppose inflammation in the body (1).
Vitamin D Deficiency
It is near impossible for most people to get enough vitamin D from food, not just vegans and vegetarians. While we can usually rely on the sun for vitamin D, in northern latitudes from October to April the lack of sun exposure means our bodies are not able to convert the UVB from the sun to vitamin D3.
Vitamin D Deficiency in Children
Severe vitamin D deficiency leads to rickets, a disease in children resulting in skeletal deformities due to the failure of bone tissue to properly mineralize (3).
Vitamin D Deficiency in Adults
In adults, vitamin D deficiency results in the inability to absorb calcium from food, and subsequent ‘stealing of calcium from bones’. This causes osteomalacia (softening of the bones caused by impaired bone metabolism), as well as an increased risk of osteoporosis and fractures.
Who Is At Risk of Vitamin D Deficiency
Risk of deficiency is not limited to those living in northern latitudes or to those following a plant-based diet. Other populations at risk include:
- Pregnant Ladies – During pregnancy vitamin D Recommended Dietary Allowance (RDA) is increased
- Those living in polluted areas – Pollution, as well as cloud coverage, impact the amount of vitamin D available
- Those with darker skin and ethnic minorities – African Americans have, on average, about half as much vitamin D in their blood as white Americas (2). Melanin, the pigment in darker skin, reduces the skin’s ability to make vitamin D in response to sunlight exposure
- The elderly population – The skin’s ability to produce vitamin D is influenced by age, and after the age of 65 the skin only generates one-fourth as much vitamin D compared to people in their 20s (2)
- Those with Crohn’s or Celiac Disease – These conditions affect the ability of the body to absorb dietary fat in the gut, which impacts absorption of fat-soluble vitamin D
Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north (in the United States, the shaded region in the map) or below 37 degrees south of the equator. People who live in these areas are at a higher risk of vitamin D deficiency (2).
Vitamin D and Autoimmune Disorders
Vitamin D Receptors (VDR) are located in tissue all throughout the body, and in all the major organs. Vitamin D is active interacts with over 3,000 genes, including some associated with cancers, autoimmune disease, and infection!
A study published in 2001 and followed 12, 055 participates for 30 years found that when children were supplemented with vitamin D for the first year and a half of life they had a significantly lower risk of developing autoimmune type 1 diabetes (4).
Another study, published in 2004, found that a higher intake of vitamin D was associated with a lower risk of rheumatoid arthritis, another autoimmune condition (5).
Vitamin D and Cancer
In terms of gold-standard of research, a randomized-controlled trial (RTC) tested the effect of vitamin D supplements on cancer. Women who took a higher dose of vitamin D (1,100 IU) combined with calcium, reduced their risk of developing non-skin cancers by 77% (6).
The only other RTC on Vitamin D and cancer found no effect on vitamin D intake and colorectal cancer – though, this study only supplemented with 400IU of vitamin D (7).
How Much Vitamin D Do We Need
The Institute for Medicine has set the RDA for vitamin D at 600 IU per day for those aged 9 to 70 (over the age of 70 the RDA is 800 IU per day), however, this amount is widely thought to be inefficient.
Author and Registered Dietitian Desiree Neilson recommends 1000 IU of vitamin D3 in the summer and 2000 IU of vitamin D3 in the winter. This is a modest but still active dose that is safe for lifelong use and within the upper limits set by the Institute of Medicine (8).
Getting Vitamin D Levels Tested
How To Know If You Are Getting Enough
The best way of knowing if you are getting enough vitamin D is to request a simple lab test at your next doctors’ visit. The test that can reliably assess your vitamin D levels is called a 25(OH)D test (not the 1,25(OH)₂D test which provides no information about vitamin D status). This lab test comes with a small fee, but is especially helpful for those at a higher risk of vitamin D deficiency (pregnancy, vegetarians/vegans, darker skin, ethnic minority, elderly, those living in northern latitudes).
Interpreting Vitamin D Lab Values
In Canada, vitamin D levels are measured in nmol/L (in the USA they are measured in ng/ml).
Most experts agree that 25(OH)D of less than 50nmol/L (20 ng/ml) is considered to be vitamin D deficiency whereas a 25(OH)D of 51- 75nmol/L (21-29 ng/ml) is considered to be insufficient. The goal should be to maintain both children and adults at a level more than 75nmol/L (30 ng/ml) to take full advantage of all the health benefits that vitamin D provides. This value meets the needs of 97.5% of the population.
Best Vitamin D Source
It is estimated that 90% of our vitamin D comes naturally through sun exposure. According to the National Institute of Health (NIH), 5 to 30 minutes of sun exposure between 10am and 3pm twice a week to the face, arms, legs, or back, without sunscreen is usually enough to get adequate vitamin D during certain months.
Food Sources of Vitamin D
Oily fish such as salmon is our main food source of vitamin D, but we can’t rely on it as our only source – it is just not sustainable (see post Is There Something Fishy About Fish Farms?)! Eggs contain some vitamin D, as well as fortified dairy and non-dairy milk alternatives.
Vitamin D Amounds In Food
See below for some of the top food sources of Vitamin D:
- Fortified Milk Alternatives – 0 – 100IU
- Salmon – fresh, wild, 3.5 oz – 400 – 600 IU
- Salmon – farmed, 3.5 oz – 100 – 250 IU
- Milk, fortified – 1 cup – 100 IU
- Yogurt, fortified – 6oz – 80 IU
- Egg, 1 large – 40 IU
- Cheese, 1 oz – 6 IU
Vitamin D in Vegetables
Many vegan resources cite mushrooms as a good source of vitamin D2, with 1 cup of portobello mushrooms said to contain up to 600 IU. While it is well recognized that exposing mushrooms to UV light can cause measurable increases in the vitamin D2 content, the amount of vitamin D2 will vary greatly depending on the type of light and duration of exposure, and can therefore be unreliable. For these reasons, we do not include mushrooms as a reliable vitamin D food for vegetarians and vegans.
Vitamin D2 Vs Vitamin D3 Supplements
There are two types of vitamin D supplements: vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol). Vitamin D2 is manufactured by the UV irradiation of yeast, and vitamin D3 is (mostly) manufactured by the irradiation of 7-dehydrocholesterol from lanolin (9), a natural, animal-derived product harvested from shorn sheep’s wool.
Vitamin D3 is more effective at raising and maintaining vitamin D levels in the body and is chemically identical to the form of vitamin D that our body produces from sun exposure (10,11). D2 is thought to be only about 60% as effective as vitamin D3 at raising serum vitamin D levels, therefore vegans who choose to supplement with D2 may need to increase intake accordingly (8).
When To Take Vitamin D Supplement
Vitamin D is a fat-soluble vitamin and is, therefore, best taken with a meal or snack that contains some fat. Really, the best time to take any supplement is when you are going to remember it. If morning is your most routine, take your vitamin D supplement with your High Protein Steel-Cut Oats with Peanut Butter this Berry Cauliflower and Greens Smoothie Bowl.
Best Vegan Vitamin D Supplement
Most vitamin D3 supplements can be derived from an animal source such as sheep’s wool (lanolin), though if you are a vegetarian/vegan who is OK with wearing wool, this would be an acceptable choice. Lichen is a vegan-friendly source of vitamin D2, though as it is less effective additional supplementation may be needed. A vegan vitamin D3 sourced from a type of wild-harvested lichen which has the ability to produce vitamin D in the natural D3 form is newly available from Whole Earth and Sea, and Nordic Naturals.
Tips For Vitamin D In Vegans and Vegetarians
- Get 5-30 minutes of sun exposure between 10am and 3pm twice a week to the face, arms, legs, or back, without sunscreen in the summer months
- Use vitamin D fortified milk alternatives
- For higher risk individuals, request a vitamin D screen and know your targets
- For those living in northern latitudes, supplement with vitamin D from October to April
What Some More Help Vitamin D Foods For Vegetarians and Vegans?
References for Vitamin D Foods For Vegetarians
1) Guillot, Xavier, et al. Vitamin D and inflammation. Joint Bone Spine 77.6 (2010): 552-557
2) Harvard Health Publishing. Harvard School of Public Health. Time For More Vitamin D.
3) Wharton B, Bishop N. Rickets. Lancet 2003;362:1389-400.
4) Hyppönen E, Läärä E, Reunanen A, Järvelin MR. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet. 2001 Nov 3;358(9292):1500-3.
5) Merlino LA, et al. Vitamin D intake is inversely associated with rheumatoid arthritis. Iowa Women’s Health Study. Arthritis Rheum. 2004 Jan;50(1):72-7.
6) Joan M Lappe, et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized controlled trial. The American Journal of Clinical Nutrition. 2007. Volume 85, Issue 6, 1, 1586–1591.
7) R. T. Chlebowski, et al. The Women’s Health Initiative randomized trial of calcium plus vitamin D: Effects on breast cancer and arthralgias. Journal of Clinical Oncology. R. T. 2006.
8) Health Canada. Updated Recommendations for calcium and Vitamin D.
9) Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357:266-81
10) Heany, Robert P., et al. Vitamin D3 is more potent than vitamin D2 in humans. The Journal of Clinical Endocrinology & Metabolism. 2011. 93: E447-E452
11) Tripkovic L, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr. 2012. 95(6):1357-64.
Photo Credit: Shayne Stadnick Photography
Rachel Dickens, The Conscious Dietitian, is a Registered Dietitian and Certified Diabetes Educator. She graduated with her Masters in Nutrition and Dietetics in 2010 from Griffith University. She strives to provide evidence-based nutrition information with a focus on plant-based nutrition, and share some of her favourite seasonal recipes and sustainable eating tips.