6 dietary supplements every plant-based client needs

Despite your client’s best dietary efforts, they may still fall short in certain nutrients, so you may need to recommend supplements to bridge the gap. From vitamin B12 to iron and omega-3’s, here’s how you can nutritionally support your plant-based clients with supplementation.

People have been flocking towards plant-based diets for various ethical and environmental reasons, making them a mainstream sensation. When done right, this eating style has a multitude of health benefits, but despite your best efforts, a diet based exclusively on plant foods can still fall short on important nutrients. 

That’s where supplementation comes into play, as it helps bridge the gap to reduce the risk of deficiency. As a dietitian, you can work with your vegetarian and vegan clients to monitor their blood levels, provide custom meal plans to address any deficiencies, and recommend certain supplements to further boost their nutrient intake. But what nutrients should you focus on, why are they important, and how do these play a role in your clients’ overall health?

Let’s dive headfirst into supplementation needs for your vegetarian and vegan clients. 

6 dietary supplements for plant-based clients

Important note: before recommending any supplements, check your client’s current medications to make sure there are no drug-nutrient interactions. 

Supplement #1: Vitamin D

Vitamin D – otherwise known as the “sunshine vitamin”- is an essential fat-soluble vitamin that is produced from cholesterol when your skin is exposed to the sun or obtained through diet as either vitamin D2 (ergocalciferol) or vitamin D3. You can find vitamin D2 in plants and yeast, whereas vitamin D3 can only be found in animal sources (such as oily fish) [11].

From anti-inflammatory properties to bone health, immune function, and brain health, vitamin D boasts a wide range of health benefits [1]. Yet, despite its importance, over 40% of Americans are deficient–as such, this is one of the most common nutrient deficiencies, and can lead to a host of negative health consequences (like constipation, confusion, bone fractures, poor appetite, fatigue, and mood swings) [13]. 

The Recommended Dietary Allowance (RDA) for vitamin D is 600 IU per day for people between the ages of 1 and 70. For adults over 70, the RDA is 800 IU per day [12]. 

Dietary sources

You can only obtain vitamin D through a few food sources. Fatty fish (such as salmon, herring, and sardines), egg yolks, and mushrooms are some good ones. While you can also obtain it through sunshine, many people choose to avoid this due to skin cancer and other harmful effects from UV rays.

Supplementation needs

Since you can only get vitamin D from a few food sources, it’s no wonder many of us fall short–especially if your client follows a vegetarian or vegan diet. As such, supplementation may be necessary to meet their needs. 

To determine the right supplement dosage, you can have your clients get their blood levels tested to see how much they may need to supplement. While studies show that supplementation is safe at up to 5,000 IU per day, you can also use a dosing range from 2 - 100 mcg depending on how deficient your client is and what their labs suggest [14,15].

Supplement #2: Vitamin B12

From DNA synthesis to red blood cell formation, vitamin B12 has many important functions in the body. As such, deficiency may result in megaloblastic anemia, weight loss, memory loss and disorientation–all of which can be quite damaging to health [2]. 

The RDA for vitamin B12 is as follows [16]:

• Older children and adults: 2.4 mcg/day
• Pregnant and breastfeeding women: 2.6 and 2.8 mcg/day, respectively
• Vegan adults: up to 250 mcg/day (this is due to B12’s poor absorption rate and a high risk of deficiency).

Dietary sources

You can find vitamin B12 in animal foods (like meat, milk, eggs, and fish) as well as nutritional yeasts, fortified breakfast cereals, tempeh, and plant-based milks.

Supplementation needs

Animal products tend to supply a larger amount of vitamin B12, and while some plant foods contain this vitamin, it’s recommended that your clients who follow a vegetarian or vegan diet be screened for deficiency via a blood sample [16]. Depending on the results, you can help them meet their needs with a supplement, B12 injections, or a high-dose oral vitamin B12. 

Supplement #3: Omega-3 fatty acids

Omega-3 fatty acids are essential for many functions throughout the body, including hormone production, brain health, immunity, and blood clotting, and cardiovascular health [3]. ALA (found in most plant foods), EPA, and DHA are the three most common types of omega-3’s. Research shows that alpha-linolenic acid (ALA) can reduce the risk of inflammation and breast cancer, and also plays a role in the brain and eye structure [3]. 

Unfortunately, studies indicate that those who eat a plant-based diet have up to 50% lower concentrations of EPA and DHA compared to their omnivorous counterparts. As such, they are at a higher risk of deficiency, which has been associated with depression, heart disease, arthritis, and various cancers [4,17,18]. 

The RDA for omega-3 fatty acids is [17]:

• ALA: 1.1-1.6 grams per day
• EPA/DHA: no current recommendation for EPA and DHA, but research indicates that 250 - 300 mg per day is sufficient for most people [17]. 

Dietary sources

Fatty fish (such as salmon, trout, tuna, and sardines) and fish oil are excellent sources of DHA and EPA, while nuts, seeds, and flaxseed oil are rich in ALA [17]. 

Supplementation needs

Since your vegetarian and vegan clients are more at risk for a deficiency, supplementation may be a good way to meet their needs. You can work with them to include vegan fish oil, EPA/DHA (marine algae) or ALA (flax oil) in their nutrition plan, but dosing will depend on your client’s level of deficiency [23]. 

Supplement #4: Calcium

Calcium is another essential nutrient that everyone needs to have in their diet, as it’s important for bone health, blood clotting, hormone secretion, and muscle function [5]. A lack of calcium can result in weak bones and osteoporosis, as the body takes calcium out of the bone to maintain calcium homeostasis. 

Here is the RDA for calcium [20]: 

• Adult men (19-70 years old) and adult women (19-50 years old): 1,000 mg
• Men and women over 70 and 50 years old, respectfully: 1,200 mg

Unfortunately, less than 22% of men and 10% of women meet the recommended calcium intake [19]. 

Dietary sources

You can obtain calcium in dairy products, but it can also be found in calcium-fortified foods (plant-based milks, orange juice, and tofu), leafy greens, broccoli, butternut squash, beans, and almonds [6].

Supplementation needs

Advising your client to take a calcium supplement can be beneficial if taken correctly. Calcium supplements are best absorbed when taken with food and taken in smaller doses (typically less than 600 milligrams at one time) [20]. It’s also recommended to pair calcium with vitamin D, as this will enhance absorption.

Note: Calcium supplementation may cause GI disturbances, so if this occurs, you should have your client try a new form, lower the dose, or take it with meals.

Supplement #5: Zinc

Zinc plays an important role in immune function, metabolism and DNA structure, which is why deficiency can lead to health problems (such as hair loss, delayed wound healing, developmental problems, and negatively affect the reproductive and central nervous systems) [21]. 

Here is the daily recommended intake for zinc [7]:

• Adults: 8–11 mg
• Pregnant women: 11–12 mg
• Lactating women: 12–13 mg 
• Vegans: >1.5 times the RDA

Dietary sources

Zinc can be found in dairy products, poultry, red meat, and certain types of seafood (such as crab and lobster). While it can also be obtained with plant-based foods (like whole grains, beans, nuts, and seeds), vegetarians and vegans are at a higher risk of deficiency since these plant foods have a lower bioavailability from zinc [21,22].

Supplementation needs

A zinc gluconate or zinc citrate supplement may be beneficial to treat deficiency, but the dosage may differ based on each client and their level of zinc deficiency.

Supplement #6: Iron

Iron is another important nutrient that is essential for cellular function, immunity, DNA synthesis, and neurological development. As such, a deficiency can spell disaster for health, as this may lead to weakness, anemia, GI distress, and impaired cognitive function [8].

The RDA for iron is [9]:

• Men and non-menstruating women: 8 mg
• Menstruating women (<18 and 19-50 years old): 15 mg and 18 mg, respectively
• Pregnant women: 27 mg
• Lactating women (19-50 years old): 9 mg
• Men and women who follow a vegetarian/vegan diet: 1.8 times the recommended RDA due to reduced bioavailability.

Dietary sources 

You can find iron in both animal flesh (such as meat, poultry, and seafood) and plants (like grains, legumes, leafy greens, tofu, and enriched cereals). The former is referred to as heme iron, while the latter is non-heme iron [8]. Unfortunately, compounds found in non-heme iron sources diminish absorption, and since non-heme iron only has a 5-12% bioavailability, those who follow a plant-based diet are more at risk for deficiency [8]. 

Supplementation needs

Depending on the level of deficiency, you can recommend a stand-alone iron supplement (contains around 350% of the DV) or a regular multivitamin (which would provide 100% of the DV). However, you should monitor your clients while taking this, as excess iron (<20 mg) from a supplement can cause gastrointestinal discomfort, constipation, nausea, vomiting, and faintness [9,10].

Summary

Supplementation for vegans and vegetarians may be necessary to boost overall health and reduce the risk of illness and chronic disease.

As a nutrition professional, you can ensure your plant-based client’s nutrient needs are met through customized meal plans and recommending supplements such as vitamin B12, vitamin D, iron, calcium, omega-3 fatty acids, and zinc.

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