Vitamin D for Plant Based Diets, Vegans, Vegetarians – Deficiency, Sources, Absorption
December 9, 2021
If you follow a plant based, vegan or vegetarian diet it may be difficult to get enough vitamin D each day. Many common food sources of vitamin D such as salmon, egg yolks and shell-fish are not eaten by vegans.
This is not just a problem for vegans. Research from the Australian Health Survey found that 23% of Australians have lower levels of Vitamin D.
What Is Vitamin D?
Vitamin D is an essential fat-soluble vitamin, which plays an important role in optimising bone health, muscles, and overall health and wellbeing. Whilst the daily needs of many nutrients is met from food alone, vitamin D can also be produced when sunlight is on the skin.
What Does Vitamin D Do?
Vitamin D has a variety of different roles in the body.
Some of these roles include:
- Helping your body absorb calcium and phosphorous from food. Calcium and phosphorus are essential minerals involved in maintaining bone health (1)
- Optimising immunity. Vitamin D deficiency has been associated with decreased autoimmunity and higher risk of infections (2)
- Mood regulation. Low levels of vitamin D may be associated with depression (3)
- Mediating inflammation in the body. Vitamin D may exhibit anti-inflammatory effects (4,5)
Plant Based Food Sources of Vitamin D:
Vitamin D exists in two forms: vitamin D2 and D3. Vitamin D2 is found in plant sources, while D3 can be produced from sun exposure or found in animal-based foods.
Food sources of vitamin D are limited, and predominantly found in animal products such oily fish, shellfish and dairy products.
While it is challenging for many people to get adequate vitamin D from food sources alone, it is increasingly difficult for people following a vegan diet due to limited vegan sources of dietary vitamin D.
Some plant-based foods do contain vitamin D naturally or through food fortification (this is where the nutrient is added into the product).
Vitamin D Vegan Foods Include:
- Fortified plant milks, such as Vitasoy Calci-plus soy milk and So Good regular soy milk
- Fortified cereals, such as Special K
- Mushrooms that have been exposed to ultraviolet light
While essential nutrients generally need to be obtained through diet, vitamin D is unique as it can also be obtained when the skin is exposed to sunlight (6).
How Can You Get Vitamin D From The Sun
As vitamin D is universally challenging to get solely from diet, many people rely on sunlight exposure to obtain their vitamin D.
While it is easy to get enough vitamin D from sunlight alone, there are some factors to be aware of that may affect vitamin D production from the sun. These include (6):
- Seasonal changes: Vitamin D deficiency is more common in the winter months due to decreased time spent outside, wearing more clothing and lower UV radiation.
- Age: Synthesis of vitamin D appears to be less efficient as people age.
- Skin type: People with darker skin may be less efficient at producing vitamin D through sunlight exposure, when compared to people with lighter skin.
- Environmental factors: These include the angle of the sun, distance from the equator and cloud coverage.
Due to the above factors, there is no standardised recommendation for how much sun exposure is needed to produce adequate vitamin D.
It is important to limit prolonged sun exposure as this can result in sunburn, skin damage and increased risk of skin cancer. This is especially important in Australia where sun exposure has been estimated to cause 95% of melanoma cases.
Vitamin D requirements for vegans
Vitamin D requirements for vegans are the same as those recommended for the general population. The below recommendations are based on adequate intake values (AI) as stated by Australia’s Nutrient Reference Values.
AI is an approximate value based on the average daily nutrient intake observed in healthy populations that is assumed to be adequate.
There is an upper level of intake (UL) for vitamin D.
This means that amounts above this value may result in harmful or adverse health effects.
The UL is set at 25μg/1000 IU for infants 1-12 months, and 80μg/3200 IU for all other populations (6).
Signs of Vitamin D Deficiency
As vitamin D is important for bone health, people who do not get enough vitamin D may be at increased risk of developing weak and brittle bones.
In children, vitamin D deficiency may increase risk of developing rickets; a bone disease characterised by soft weakened bones, and bone deformities.
Other signs and symptoms of vitamin D deficiency include:
Is being vegan a risk factor for developing a vitamin D deficiency?
Foods that contain vitamin D are mostly found in animal-based foods, therefore vegans may be at a heightened risk of developing a vitamin D deficiency.
However, as vitamin D can be produced from the sun, diet is not the sole factor when determining the risk of deficiency.
Other factors that may increase risk of deficiency include lifestyle factors such as time spent indoors, age and skin type.
Improving Absorption of Vitamin D
As vitamin D is a fat-soluble vitamin, it requires fat to enhance absorption.
Fat can be found in foods such as avocado, olive oil, nuts, seeds, peanut butter and tahini.
Some vitamin D supplements may contain fats such as olive or coconut oils to help with absorption.
If the supplement doesn’t contain a source of fat, be sure to take the supplement with foods that contain fat, such as oils, avocados, nuts or seeds.
Should vegans supplement vitamin D?
If you struggle to get enough vitamin D through foods and sun exposure, then a vitamin D supplement should be considered to avoid deficiency.
You can find out if you’re getting enough vitamin D through getting your levels checked by your GP.
When choosing your vitamin D supplement, there are a few important considerations to be aware of:
- Make sure it is appropriate for vegans. Many vitamin D supplements are derived from animal products such as lanolin and are therefore not vegan-friendly.
- Opt for the D3 form over D2. Vitamin D3 appears to be more effective at raising blood levels of vitamin D, however it is predominantly found in animal-based products. Fortunately, a vegan-friendly source of vitamin D3 exists from an algae-fungal organism called lichen.
This blog was co-written by PNW Clinic founder Kiah Paetz and student dietitian by Jade Wrigley.