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March 28, 2023

Are Supplements Needed in a Plant-Based Diet?

by Virginia Barringer, MS, RD, LDN, CDCES, BCADM

Whether from family, friends, colleagues, newspapers, social media, or TV, it seems we are surrounded by recommendations for taking all types of vitamins and supplements, but do we all really need these extra nutrients? Over half of the US population take them, and 70% of people over 65 years old take a multivitamin (MVI) or supplement. It is a billion-dollar industry, so there is great incentive to recommend and sell supplements.

Who might benefit from supplements?

There are many situations where additional nutrients might be of benefit, such as women during pregnancy, persons with malabsorption problems from illness or surgery, or those on special diets for certain medical conditions or to aid with weight loss. We will focus on people who are following plant-based, vegetarian or vegan diets. Let us start by defining plant-based diets.

The terms “vegan” (no foods from animals, no dairy or eggs) and “vegetarian” (no meat but do eat dairy and eggs) may be familiar but newer hybrid terms such as “pescatarian” (no meat except fish) or “semi-vegetarian” (occasionally eat meat, poultry or fish) and “plant-based”,  “plant-forward” or “flexitarian” may be used to describe the blurring of lines between all types of plant based eating patterns.

Nutrients of Risk

The nutrients that could be lacking in a plant-based diet include:


While some people believe that protein can be inadequate in vegetarians and vegans, this is not supported by data. All of the essential amino acids (building blocks of protein) can be provided by a variety of plant foods throughout the day in healthy individuals. It is easier to meet protein needs in a vegetarian diet because of protein sources like milk, eggs, and cheese, but adequate amounts of protein can also be achieved in a vegan diet containing legumes, grains, nuts, nut butters, seeds, soy foods, and even some vegetables that contain protein. Vegetarians and vegans typically meet or exceed the Dietary Reference Intakes (DRI) for protein, however some women on a more restrictive vegan diet are at higher risk of not meeting the goals. Among the essential amino acids, lysine can be limited in vegan diets so vegans should make sure they eat some lysine rich foods like tofu, tempeh, soy foods, lentils and seitan.


Those who eat a diet without heme iron (found in meats, fish, and poultry) may develop iron deficiency anemia if they do not include adequate non-heme iron foods (beans and lentils) in the diet. Vegetarians and vegans should consume almost double the non-heme iron recommended for animal protein eaters. Non-heme iron is not well-absorbed, so either greater quantities of these foods should be consumed or careful attention should be given to how they are eaten in order to improve absorption (consuming with vitamin C-rich foods while avoiding eating with calcium-rich foods, calcium supplements, or tea).

Vitamin B12

Vitamin B12 is found naturally in animal products like beef, pork, chicken, fish, eggs, dairy so if ones diet does not include any animal products, they may become deficient over time unless supplemented with pills, shots, or foods high in B12, like nutritional yeast. Dried edible seaweed (used to make sushi rolls), is sometimes promoted as a plant source of vitamin B12. Although most seaweed contains small amounts of active vitamin B12, the amount is highly variable among types of seaweed, with some containing none. Therefore, it is not considered a reliable food source. There is no upper limit for vitamin B12, as it is water soluble, and excess will be excreted in the urine. However, there is some evidence that supplements of 25 mcg per day or higher may increase the risk of bone fractures.

Vitamin D

There is mixed data on whether vitamin D status is related to vegetarian status or not, but vegans who avoid milk and egg (yolks) may be at greater risk for inadequate vitamin D and may benefit from supplementation. Regarding the type of supplement, some vegans may want to avoid vitamin D3 because it comes from an animal source whereas vitamin D2 is made from yeast. Another important factor to consider is that vitamin D status appears to be related more to regular sun exposure than diet.


Calcium supplements may be recommended in vegetarians and vegans whose intakes of low-fat dairy foods (milk, plant based milks fortified with calcium, cheese and yogurt) are low. Green leafy vegetables are a good source of calcium though do not contain as much as dairy foods. Spinach and Swiss chard however are not good sources of calcium because of their high oxalate content which can interfere with calcium absorption.


Meats, poultry, seafood, oysters, and dairy are rich in zinc. Some plant foods like legumes, nuts, seeds and whole grains are also good sources of zinc, although they also contain phytates that can bind to the mineral, lowering its absorption. Soaking, sprouting and fermenting these plant foods can increase their bioavailability.


There are two classes of omega-3 fats; the plant form called alpha linolenic acid (ALA), which is found in canola, soybean and vegetable oils, ground flax seed, some vegetables, walnuts, and soy. The animal forms, called EPA and DHA are mainly found in fish and seafood. A very small amount of ALA can be converted to EPA and DHA, so consuming additional ALA can boost omega-3s if no fish or seafood is consumed. EPA and DHA are important in fetal brain development, so omega-3 or marine algae supplements may be recommended for pregnant and lactating women to support growth and development of the fetus and infant.


Iodine deficiency is very rare in the US due to the iodine fortification of salt. It is naturally found in fish and dairy products. It is also present in varying amounts in fruits and vegetables. Insufficient iodine levels have been reported among vegetarians and vegans, although how commonly this occurs is unknown.

So, what is the best advice for vegetarians and vegans?

Choose a variety of foods from fruits, vegetables, whole grains, legumes, beans, nuts, nut butters, seeds, and if appropriate, dairy foods, eggs, and soy foods. Some individuals may need to consider supplementation (for example Calcium, vitamin B12 or vitamin D) as noted above. The USDA site has recommendations for nutritionally adequate plant-based eating patterns. You can also find plant-based recipes in the Avance Care Nutrition Cookbook.

If you want to know more about vitamin and mineral intake specific to your plant based eating pattern, schedule an appointment with an Avance Care dietitian, who can help you plan a nutritionally adequate plant-based diet. Appointments can be telehealth from the convenience of your home or office or schedule an in person meeting at one of our many locations. Call our Wellness Coordinator today at 919.237.1337, option 4 or schedule online at


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  4. The Role of Plant-Based Diets in Health. SCAN’S PULSE. Spring 2013; vol. 32, No.2
  5. A plant-based diet – good for us and for the planet. MJA Open 1. 2012;Suppl 2; June 4:5-45

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