Should I Be Taking Supplements? Part 2

Welcome to Part 2 of the vitamins and minerals post! If you haven’t read Part One, I recommend you head on over there before diving in here. To recap, my goal for these posts is to provide advice on vitamins and minerals of concern for healthy people who eat very little or no animal products. Getting enough nutrients while eating a plant-based diet is not hard, you just have to know what you’re doing. In part one, we learned about vitamin B12, iron, calcium, and vitamin D. This go-round, I’ll hit on omega-3 fats (not a vitamin or mineral, but important nonetheless!), vitamin A, zinc, and iodine. And because winter is upon us here in the U.S., Sarah is gonna throw in some information on whether or not you should be taking any supplements to stave off cold weather illnesses. Let’s start with a big one: omega-3 fats.

Omega-3 fats

The subject of omega-3 fats is a bit tricky, so bear with me. Omega-3 fats, along with omega-6 fats, are essential fats (or fatty acids as we like to say in the nutrition world) that we gotta eat to keep our health optimal. There are different types of omega-3’s: There’s the shorter alpha-linolenic acid (ALA) found in plant foods and the longer docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), both which can be made by the body from ALA or ingested. Omega-3’s play a role in brain/eye function, blood clotting, blood pressure, and formation of triglycerides (the fat in your blood). They have anti-inflammatory properties and play a role in improving cardiovascular health as well.

The deal is, ALA, which is the omega-3 found in plants, is not very efficiently converted to DHA and EPA, a step necessary to reap the benefits of these fats. DHA and EPA are found in fatty fish, so it’s recommended to eat fish regularly to get enough of these long-chain omega-3 fats. If you don’t eat fish, there are algae-derived supplements available but, unfortunately, the research on this is inconclusive, so it’s difficult to make a blanket recommendation for supplementing. The book Vegan for Life gives recommendations for small amounts of an algae-derived DHA supplement: 200-300 mg of DHA (or DHA and EPA) taken every 2-3 days. I think this is wise to do if you don’t eat fish, but I would check with your doc before starting this supplement. If you do eat fish, the American Heart Association recommends two 3.5 ounce servings of fatty fish (salmon, mackerel, herring, lake trout, sardines, or albacore tuna) per week to get enough DHA and EPA. Fish oil supplementation is commonplace among those looking to prevent heart disease and other conditions related to inflammation. However, evidence to recommend them for prevention is still not convincing.   

I do recommend making sure you get enough ALA from plant sources if you’re not a fish eater. In the U.S., we (vegetarians included) tend to get way more of the other essential fat, omega-6, and not enough omega-3. Getting excessive amounts of omega-6 fats (high in corn, soy, safflower, sunflower, and sesame oils) can make the conversion of ALA even less efficient and too much can increase inflammation as well. Find some tips for getting the right ratio here. Very high intakes of ALA may not be advisable, but getting enough is important. Each item on the list of dietary sources below provides roughly ¼ of the amount of ALA needed for a male and ⅓ of the amount needed for a female. So a guy would need to eat 4 servings from the list per day and a gal would need to eat 3.

Adequate Intake: For ALA – 1.6 grams a day for men and 1.1 grams a day for women

Supplement recommended?

ALA: No, but make sure to get dietary sources.

DHA/EPA: For those who do not eat fish, evidence is inconclusive for algae-derived DHA supplements, but small amounts from supplements may be appropriate, i.e. 200-300 mg of DHA (or DHA/EPA combined) every 2-3 days (check with your doc before starting). If you eat fish, chow down on fatty fish 2 times per week instead.

Dietary sources of ALA:2

1 teaspoon canola oil, ¼ teaspoon flaxseed oil, ⅔ teaspoon hempseed oil, 1 teaspoon walnut oil, 2 teaspoons ground English walnuts or 1 walnut half, 1 teaspoon ground flaxseeds, ½ cup cooked soybeans, 1 cup firm tofu, 1 cup tempeh, 2 tablespoons soynuts

Whew! That was a tough one. On to some “lighter” topics.

Vitamin A

Vitamin A is such an interesting group of vitamins. That’s right, when we talk about vitamin A, we are actually referring to a group of compounds called retinoids as well as their precursors, carotenoids. Your body uses vitamin A for a host of functions including the visual cycle, skin maintenance, immunity, bone development, fertility/reproduction, and iron transport to name a few. Retinoids are considered the active form of vitamin A and are found in animal products. Plants, however, are chock full of carotenoids, some of which are formed into retinoids. This is why they are grouped in with the vitamin A family. In addition to their role as a vitamin A precursor, carotenoids function as an antioxidant and play a role in vision and immunity.

If you don’t eat many animal products, you’re at an increased risk of vitamin A deficiency for a few reasons: the active form of vitamin A is only found in animal products, intestinal absorption of carotenoids is low, and only certain carotenoids can be formed into active vitamin A. Those carotenoids that can be formed into vitamin are termed provitamin A. Fun fact: Beta-carotene is the most notorious of the carotenoids and is most efficiently formed into active vitamin A. This make vegetables high in beta-carotene particularly important for veg heads. Consider drinking ¼ cup carrot juice daily as well as eating a colorful diet to help you to get enough carotenoids from plants. Pro tip: Eat your carotenoids with a source of fat (like olive oil) as this, as well as cooking, increases absorption.

Recommended Dietary Allowance (RDA): 700 micrograms (mcg) per day for adult women and 900 mcg per day for adult men

Supplement recommended?: No, get a variety of colorful veggies to meet your needs. However, a standard multivitamin with minerals will have from 2000-5000 IU, which should be safe and will help you meet your needs.

Dietary sources: The highest sources of provitamin A carotenoids are carrots (½ cup raw: 459 mcg), broccoli (½ cup cooked: 60 mcg), cantaloupe (½ cup raw: 135 mcg), and squash (½ cup cooked 10 mcg). Many breakfast cereals are fortified with vitamin A, but the amount varies by brand. Visit the NIH website for a full list of sources.


Zinc is a fantastically (that’s a word, right?) important mineral. In fact, it assists more than 100 enzymes and plays a role in protein synthesis, wound healing, DNA synthesis, growth and development, and is needed for taste and smell. Add to that the fact that your body doesn’t have a storage system for zinc and we have a pretty important little mineral on our hands. Many experts believe marginal zinc deficiency is more common than we are aware of, but we don’t have a good blood test for zinc so this is difficult to diagnose. Zinc has some of the same issues with absorption that non-heme iron has – namely that plant sources are not as absorbable and foods with phytates (coffee, tea, whole grains, spinach, chocolate) can decrease its absorption. Plant sources also don’t have as much zinc as animal sources. All of this creates a perfect storm for not getting what you need if you are not diligent. I recommend only drinking coffee and tea between meals, making sure your multivitamin contains zinc, and getting at least three good sources a day.

RDA: 8 mg per day for adult women and 11 mg per day for adult men.

Supplement recommended?: Yes, make sure your multivitamin/mineral supplement contains around 10 mg of zinc.

Dietary sources: Sources from plants include breakfast cereal fortified with 25% of the daily value for zinc (¾ cup: 3.8 mg), vegetarian baked beans (½ cup: 2.9 mg), wheat germ (2 tablespoons: 2.7 mg), roasted cashews (1 oz: 1.6 mg), chickpeas (½ cup cooked: 1.3 mg), lentils (½ cup cooked: 1.3 mg), tahini (2 T: 1.4 mg), granola (¼ cup: 1.3 mg), roasted almonds (1 oz: 0.9 mg), kidney beans (½ cup cooked: 0.9 mg). Visit the NIH website for a full list of sources.


Iodine is not typically on most folk’s radar. This is because deficiency is rare in the U.S. since iodine was added to salt. Iodine’s most notable role in the body is as a component of thyroid hormones. It also has roles in carb, protein, and fat metabolism; mental development; gene expression; and metabolic rate. Because iodine is highest in animal products like fish and dairy and because those who avoid animal products may tend to eat a largely unprocessed diet that contains little iodized salt, deficiency of iodine can become a concern. Vegetables contain iodine, but the amount varies a lot based on the iodine content of the soil in which they were grown, so they can be unreliable sources. Vegan for Life provides some recommendations that I feel apply here, especially if you avoid seafood and dairy. The authors recommend if you salt your food, you do so with iodized salt. If you don’t add salt, don’t start. You can simply make sure your multivitamin/mineral has iodine in it. Sea salt typically does not have iodine added, but will contain varying amounts based on where it’s from, which makes it an inconsistent source.

RDA: 150 micrograms per day for adult men and women.

Supplement recommended?: If you avoid dairy and seafood most or all of the time and don’t add salt to your food, I suggest you ensure your multivitamin/mineral has around 75 mcg of iodine.

Dietary sources: Plant-based sources include iodized salt (¼ tsp: 71 mcg), enriched white bread (2 slices: 45 mcg), 5 prunes (5 dried: 13 mcg). Visit the NIH website for a full list of sources.

Thanks so much for reading! These posts were very rewarding, yet challenging to write!  -Lindsey

A quick note from Sarah:

Oh, hey cold and flu season, we really haven’t missed you. Ironically, I write this with a box of tissues and mug of hot tea nearby, thanks to a nasty respiratory bug. So, which supplements are really “worth it” when trying to build immunity during the chilly winter months? I always recommend starting with a good vitamin C + zinc supplement. While a meta analysis showed vitamin C does not prevent the development of common colds, it may improve symptoms in some people. An article published in the Journal of International Medical Research recommends 1000 mg vitamin C + 10 mg zinc to help improve symptoms of the common cold. You may also want to check out a vitamin D supplement for immune support as we now know deficiencies are associated with increased risk for infection.

Last but not least, let’s briefly talk fungi. In the world of integrative nutrition, mushrooms and mushroom extracts are really starting to turn heads, thanks to their many immune boosting properties. While eastern European countries have been all over this for thousands of years, more research is demonstrating that mushrooms seem to also display certain antiviral, antibacterial, and anti-parasitic effects. Lots of great supplement companies are already incorporating mushroom extracts into their immunity blends, which is super cool and a pretty safe way to begin adding them to your regimen. Some are ingestible, others not, so we really could write a whole separate post on mushrooms, but until then, check out this great article from Today’s Dietitian.

Credits // Author: Lindsey Kelsay with contribution from Sarah O’Callaghan. Photo by: Emma Chapman.
References: Gröber, U. (2009). Micronutrients: Metabolic Tuning – Prevention – Therapy. Stuttgart, Germany: Wissenschaftliche Verlagsgesellschaft mbH.
Norris, J., Messina, V. (2011) Vegan For Life: Everything You Need to Know to Be Healthy and Fit on a Plant-Based Diet. Da Capo Press.
Marian, M., & Sacks, G. (2009). Micronutrients and older adults. Nutrition in Clinical Practice : Official Publication of the American Society for Parenteral and Enteral Nutrition, 24(2), 179–95.


  • I’d be interested in understanding that if I do eat meat, should I take these suplements anyway depending on the type of meat I usually eat?

    • Catherine – If you eat meat, fish, and dairy regularly as well as a variety of colorful fruits and vegetables, I generally recommend a multivitamin/mineral (that meets the suggestions from posts 1 & 2) and 1000 IU vitamin D (from all supplement sources). If you don’t get 3 dairy servings or plant sources listed in post 1, you may consider supplementing calcium as well.

  • I’ve been having a lot of thyroid issues and constantly feel tired and fatigued so I’ve been looking into some supplements that might help with this. Really glad you guys posted something about this. It was incredibly helpful!

  • I really loved reading your blog. I also found your posts very interesting. In fact after reading, I had to go show it to my friend and he ejoyed it as well!

  • Yum, these carrots look delicious. Love this!
    xo, Meghan |

  • I love the detailing on Vitamin A. There’s a big difference between the different types of it and it should really be known to the public. I’ve landed in the hospital once because I was overdosing on the wrong form of it!

    Charmaine Ng | Architecture & Lifestyle Blog

  • This is such a great topic! I constantly think about this!

    Michelle ||

  • I am LOVING this series, and how it’s so evidence based and opposite of the clickbait fear-mongering usual stuff you often hear about nutrition nowadays (when you said peer-reviewed in the first supplements post my scientist heart just about exploded). Thanks for the tip about tea affecting absorption, I didn’t know that!

    • Julia – LOL – it’s the little things that make our science minds happy, right? So glad you are reading and enjoying!

  • I’m a scientist and this is probably one of the absolute best explainers on supplements I’ve seen on the internet outside of my PubMed searches! I actually had a friend in college who did her thesis project on how zinc may help with colds (something about disrupting viral envelopes).

    The new department chair at my job actually spent the past few years of her career showing a link between low Omega-3 intake and the development of certain mental disorders in at-risk youth. It’s fascinating and sad to see how far-reaching the effects of poor nutrition are!

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