Selenium on a Vegan Diet – Sources, Deficiency, Supplements

Getting enough selenium on a vegan diet can be challenging, but possible if you regularly include the right sources.

You may not have considered the impact of selenium on your health, so let’s take a deep dive and understand why it’s important and how to make sure we are getting enough each day. 

Why is selenium important? 

Selenium is an essential mineral needed in the body for various roles. As we don’t produce this mineral in our body, we need to obtain it from dietary sources. It assists with making many different proteins that help with cell membrane integrity. It is also an active component in various enzymes and assists with metabolism (1, 2). 

Selenium also has antioxidant-like properties that help protect our cells and DNA from damage caused by free radicals (1). Free radicals can build up from natural byproducts of chemical reactions within the body such as metabolism. However, external sources such as cigarette smoke and pollution can also cause free radicals to enter the body.

There are many other areas that this mineral assists in. Some of these include: 

Thyroid health

Selenium is found in the body in the highest concentrations within the thyroid gland. Many enzymes within the thyroid contain this compound, and these are responsible for helping to regulate thyroid function (1, 4). This, in turn, helps to regulate our metabolism.

When severe selenium deficiency appears, it may lead to thyroid conditions such as Hashimoto’s and Graves’ disease (4,6). These conditions result in body attacking the thyroid gland, leading to an overactive or underactive thyroid (6).

Heart health

As mentioned, this mineral is a strong antioxidant and can protect against heart diseases. Many conditions that affect the heart can be a result of oxidative stress, a process in which the number of free radicals is unbalanced with the number of antioxidants.

Oxidative stress can also cause things like inflammation (4). Selenium can also assist with producing other antioxidants such as glutathione peroxidase, which acts to protect heart health.

Immunity

As discussed, this compound plays a role in lowering oxidative stress which therefore helps to lower inflammation and increase immunity. This mineral also boosts our immune response against bacteria and viruses (6). Additionally, several studies have shown that selenium deficiency may slow down immune cell response (5).

While there is limited research, some studies have shown that adequate selenium intake can be protective against prostate and oesophageal cancer. However, more investigation is needed (1).

Selenium requirements on a vegan diet

Selenium requirements vary depending on age and gender. The recommended dietary intake as measured by the Nutrient Reference Values for Australia and New Zealand is listed below (1).

It is important to note that requirements are the highest for men, and women that are pregnant or lactating. 

Consuming over the upper limit (UL) per day is not advised as long-term overconsumption is linked to toxicity. Having less than the UL per day is unlikely to produce any harmful outcomes on health.

Sources of selenium on a vegan diet

The amount of selenium found in foods will vary depending on the soil that the food is grown in (1,2). Interestingly, levels of selenium in soil found in New Zealand and China are lower than in many other countries.

The main dietary sources of this mineral are chicken, eggs, seafood and meat. Fortunately, there are still many plant-based sources to choose from.

Some of these can be found in the table below. These values were taken from a New Zealand database, so amounts may vary slightly within Australia (3).

Many rich sources of plant-based selenium come from nuts, seeds and legumes.

Brazil nuts are an excellent source of this mineral, with only 1-2 Brazil nuts meeting 100% of daily requirements (3). Bearing in mind that the upper level for selenium intake is 400µg/day, eating too many brazil nuts over time may cause selenium toxicity.

For those with a nut allergy (or who dislike Brazil nuts), focusing on legumes and fortified cereals can assist with meeting daily requirements.

Selenium-rich day on a plate

To ensure you’re eating enough of this nutrient throughout the day, here is an example of how to incorporate selenium-rich foods in every meal.

Breakfast – approx. 9µg

3 Weetbix biscuits (45g), ½ cup soy milk topped with 1 medium banana, 3 sliced strawberries and handful blueberries

Lunch – approx. 15µg

Salad sandwich made on wholegrain bread with lettuce, tomato, onion, smashed chickpeas and avocado

Dinner – approx. 55µg

Lentil and veggie curry with ½ cup mushrooms, 1 cup lentils, broccoli, carrot and peas

Snacks – approx. 3µg

Smoothie with ½ banana, 1 tbsp peanut butter, 1 cup oat milk, 1 scoop protein powder

Total intake for the day – approx. 82µg 

If you enjoy Brazil nuts, you can simply include 1-2 nuts each day to meet your daily selenium requirements.

Does following a vegan diet affect your risk of selenium deficiency?

As previously stated, selenium concentrations in soil vary all over the world, meaning that intake and risk of deficiency can differ slightly from country to country. While the richest sources of this mineral found in Australia originate from meat and animal products, there isn’t a high risk of deficiency for vegans and vegetarians as there are a variety of other plant-based sources to choose from. 

Those with a higher risk of deficiency include those with gut conditions such as Crohn’s disease, or people receiving dialysis as absorption may be poor (4). 

Signs of a deficiency

While insufficient selenium intake is rare, those with a deficiency in this mineral may experience some of these signs and symptoms:

• Increase in viral infections (2)
• Impaired reproduction (2)
• Low mood (2)
• Thyroid function issues (2)
• Cardiovascular disease (2)
• Inflammatory conditions (2)

In China, extreme deficiency can result in a condition called Keshan disease (1). This is a type of heart disease that can be fatal. Another form of extreme deficiency is Kashin-Beck disease, a form of osteoarthritis that affects the bones and joints (4).

Selenium toxicity 

As mentioned previously, brazil nuts are an excellent source of this mineral, however it is important to be aware of risks of consuming too much. Toxicity of this compound can result in adverse side effects.

Some of these include:

• Brittleness and loss of hair and nails (1, 2)
• Skin lesions (2)
• Gastrointestinal disturbances (2)
• Effects on nervous system ((2)
• Garlic-smelling breath (4)
• Metallic taste on the tongue (4)

Some studies have found that selenium toxicity led to an increase of skin cancer cells in those taking 200µg supplements (amongst a population that already had high baseline selenium levels). However, it cannot be determined how this would translate to the general public (1).

Do you need selenium supplements on a vegan diet?

For those unable to meet selenium requirements, there are various supplements on the market. The most popular forms are selenomethionine or selenite. Selenomethionine has been shown to offer a higher absorption rate, meaning it may be a preferred source (4). Many supplements will come in doses ranging from 100µg-400µg. 

While it is entirely possible to meet requirements with a food-first approach, there are those that may need a supplement to assist with daily intake.

Examples include those that are plant-based with a nut allergy or have a low intake of legumes and seeds. However, to minimise the risk of toxicity, it is important to work closely with a health professional before commencing any supplementation regime. 

Summary

Selenium plays an important role in many parts of the body. It is responsible for various chemical reactions, assists with thyroid function, and provides protection from cell damage.

Brazil nuts are an excellent source to maintain requirements, however, there are many other plant-based alternatives too.

If you are wondering whether you are meeting your nutritional needs on a vegan or plant-based diet, you can book a consult with one of our PNW Clinic dietitians today.

References

1. https://www.nrv.gov.au/nutrients/selenium
2. https://www.foodstandards.gov.au/publications/documents/ATDS.pdf
3. https://www.foodcomposition.co.nz/search/nutrient?code=SE&group=Q
4. https://www.hsph.harvard.edu/nutritionsource/selenium/#:~:text=Selenium%20is%20an%20essential%20component,the%20metabolism%20of%20thyroid%20hormones
5. https://pubmed.ncbi.nlm.nih.gov/18384097/
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5307254/

This article was co-written by PNW Clinic dietitian Megan Boswell and student dietitian Leanna Fyffe.