In my last post on plant-based protein sources, I casually mentioned the topic of vitamin and mineral supplements. With that in mind, this post felt like a timely opportunity to formally tackle the topic. From reader comments, it sounds like a lot of you have questions about getting enough vitamins and minerals and when to supplement. And who can blame you? It’s a BIG topic. During the writing process, it became obvious that it was too much to digest (pun intended) in just one post. So I decided to break it down into two bite-size pieces. Here is Part One:
First, a little background: Nutrients are those elusive little creatures we must ingest because our body has gotta have ’em. We either can’t make them at all or can’t make enough to satisfy all the body’s processes. Micronutrients (A.K.A. vitamins and minerals) are distinguished from macronutrients (carbs, protein, and fat), in that we need less of them and they don’t provide energy in the form of calories. Nonetheless, micronutrients are still super-vital and not getting enough can wreak havoc on your bod. (Fun fact: The word vitamin comes from the phrase “vital amine.”) If you eat the SAD (Standard American Diet), you’re likely not getting enough. Now, truth be told, a plant-based diet is a far cry from the SAD, but when you’re eliminating groups of food you want to make sure you’re not removing groups of vitamins along with.
Before we get too far into this, I want to say I’ve done a lot of reading and research on this topic and what comes next is my best estimation of micronutrients of concern for those who eat mostly plants. In keeping with Weekday Weekend, my target audience is someone who may eat eggs occasionally, but not every day and is avoiding dairy most days. I’ve come across multiple sources that recommended a lot of different things, and if I omitted those things, it was because I didn’t feel that the peer-reviewed evidence I found supported it. That doesn’t necessarily mean the recommendation was not valid, but that I wasn’t comfortable recommending it for general health or had evidence that led me to believe it may not be valid. My goal when providing these recommendations is to optimize health while minimizing the risk of harm for plant-based eaters. I also just want the reader to keep in mind that these recommendations are not meant to treat any disease or condition. I am assuming a healthy population here. If you have questions about a specific disease, I recommend you speak with a primary care provider and/or a registered dietitian who is familiar with your medical history (you can search for a dietitian in your area here).
So the question is, is it really possible to get all of the vitamins and minerals needed from only plants? With vitamin B12 as an exception, the answer is yes. This, however, does not mean those who eat mostly plants are actually achieving this. Without knowledgeable planning, herbivores are at risk for deficiency of certain vitamins and minerals. For starters, I recommend taking a daily multivitamin/mineral supplement (see Sarah’s note on brands we like below).
The following sections hopefully provide a logical explanation of which micronutrients are of concern, how much you need and when I would recommend a supplement. The National Institutes of Health’s (NIH) Office of Dietary Supplements’ website has tables that list common plant food sources of each micronutrient which can supplement the lists I’ve given. You should note that some food sources listed have been fortified with the micronutrient, i.e. they have had it added to increase the content.
I’ve included the Recommended Dietary Allowance (RDA) of each nutrient below. This, simply put, is the daily amount of the nutrient that should meet the needs of most healthy people.
B12 is first on my list for a reason. While controversy exists over whether or not there are sources of vitamin B12 from plant origin, for me, it’s a no-brainer; Vitamin B12 is only made by bacteria found in animals and should be ingested in supplement or fortified form for those who eat limited amounts of animal products.(1) Human intestinal bacteria actually make it, but it’s too far down in the intestines to be absorbed. Yes, you can get enough from plant foods fortified with vitamin B12. However, you don’t want to mess around with deficiency of this vitamin (think anemia and potentially irreversible nerve damage ), so I absolutely recommend supplementing. I’ve listed fortified plant sources below simply for reference as the NIH website doesn’t have these listed.
RDA for 19 y/o and older: 2.4 micrograms (mcg) per day
Supplement Recommended?: Yes, containing 10-100 mcg cyanocobalamin (a type of vitamin B12) per day by mouth for prevention. (2) Check your multivitamin’s label to see if it has at least 10 mcg before buying a separate supplement.
Dietary sources: fortified meat substitutes (1-3 mcg, varies by brand), fortified soymilk (1-3 mcg, varies by brand), 1 T fortified nutritional yeast (4 mcg). See food label for specific content.
Iron is a tricky nutrient for plant-only or plant-based eaters because the form of iron that’s in non-animal sources (called non-heme iron) is not as easily absorbed as the form in animal sources (heme iron). Absorption of non-heme iron is reduced by certain things (coffee, tea, spinach, chocolate, whole grains, egg yolk, medications that decrease stomach secretions) and is enhanced by others (vitamin C, citric acid, stomach secretions, meats). Iron is an important component of blood and plays a role in cellular energy production and DNA synthesis.(2). Needless to say, you don’t want to be without it.
Did you know vegetarians generally eat more iron than meat-eaters? Unfortunately, it is in the less-absorbable non-heme form. One trick to increasing absorbability is to combine each meal with a good source of vitamin C like bell peppers, orange juice, an orange, or strawberries.
RDA: Men 19 y/o and older 8 milligrams (mg) per day; Women 19-50 y/o 18 mg or > 50 y/o 8 mg each day
Supplement Recommended?: Not for general health (2), although menstruating women are at higher risk of deficiency due to menstrual blood loss. I recommend consulting with a physician prior to starting iron supplementation other than what is in a standard multivitamin/mineral supplement.
Dietary sources: 1 serving of breakfast cereals fortified with 100% of the DV for iron (18 mg), 1 cup white beans (8 mg), 3 oz 45-69% cacao dark chocolate (7 mg), 1/2 cup boiled lentils (3 mg), 1/2 cup boiled spinach (3 mg), 1/2 cup firm tofu (3 mg), 1/2 cup kidney beans (2 mg).
Calcium is a mineral that plays a role in important things like bone health, muscle contractions, nerve impulse transmission, blood clotting, et cetera, et cetera.(2) Very necessary stuff. The calcium level in your blood is kept pretty constant to maintain these processes and if you don’t take in enough (or excrete too much in your urine), your body will pull from your bones to maintain that blood level. This is how chronic low intake of calcium can impact your bones.
While it is certainly possible for plants to provide enough calcium, that doesn’t mean it’s actually happening. Wild, leafy greens are your highest plant source, but the greens you buy in the store are going to be cultivated and the content is likely quite a bit lower than the wild counterpart. This, unfortunately, may be true for many of the modern or industrialized versions of food our ancestors used to rely on for calcium.(1) Other than fortified foods, dairy does provide the most calcium, but if you mostly (or completely) avoid dairy, you need to be eating at least two good sources, separated into three times a day for best absorption (that’s six total). If you don’t think you can prescribe to this, I would suggest a supplement. I’ve listed plant sources that meet the definition of a “good source” (10-19% of the recommended intake) or a “high source” (>/= 20% of the recommended intake) because the NIH site does not list many of these.
RDA for 19 y/o and older: 1000-1200 mg per day
Supplement Recommended?: Yes, if you can’t consume two good sources, three times daily. I suggest 500 mg once or twice daily depending on your intake of other sources.(1) Calcium supplements should be consumed with a meal as well as vitamin D (see next section) for best absorption. Again, be sure to check how much is in your multivitamin/mineral supplement.
Dietary sources: ½ cup cooked collard greens (133 mg), ½ cup boiled turnip greens (100 mg), 1 cup cooked kale (100 mg), 1 cup cooked bok choy (158 mg), 1 cup dried figs (241 mg), 1 cup cooked soybeans (174 mg), 2 T sesame seeds (140 mg), 2 T sesame tahini (128 mg), 1 cup calcium fortified juice (300 mg), 1 cup calcium fortified plant milks (like soy, rice, or almond – 300 mg), ½ cup firm or regular calcium-set tofu (100-300 mg), calcium fortified cereal (100-1000 mg, varies by brand).(1,2)
Vitamin D is my favorite nutrient to learn about. I mean, this vitamin does so many things it’ll make your head spin. One of its most notorious roles is in maintaining calcium absorption in the intestines and excretion in the kidneys(2), which is why it should be eaten along with calcium for best absorption. It also has functions in skin health, muscle function, hormone regulation, insulin secretion, and may have anticancer properties.(2) Pretty versatile, huh? It can be made by our skin when we get sun, but many of us don’t spend enough time in said sun to make what we need.
There is also some controversy over the RDA. (Are you sensing a theme in nutrition research?) A group of researchers found that it may have been miscalculated and should actually be much higher than the RDA’s 600 IU’s (IU = International Units—simply a unit of measurement). I am of this school of thought so I’ll give recommendations from my favorite vitamin D researcher, Dr. Robert P. Heaney, in addition to the RDA.
RDA for 19-70 y/o: 600 IU
Supplement Recommended?: Yes, I would suggest everyone, including plant-based eaters, consider a vitamin D supplement unless you get regular sunlight (10-30 minutes several times per week). A daily supplement of 1000 IU of vitamin D3 – from all supplements so check your multivitamin – seems to be safe for healthy adults. Dr. Heaney suggests getting a vitamin D blood test first and, I agree, this is wise and ensures a doctor’s supervision. Vitamin D is one of those vitamins that you can get too much of, so you want to be cautious. If your blood level is low, your doctor will have guidance on how to proceed with supplementing. General recommendations are for the blood level to be > 30 ng/mL (4), but Dr. Heaney goes further and recommends > 40 ng/mL(3). Seek guidance from your doctor on the level that is right for you. Also, keep in mind if you get a lot more sun in the summer months, you may not need to take the vitamin D supplement during that time.
Dietary sources: There are not many sources in general and even fewer from plants which is why many need a supplement. I’ve seen it supplemented in various amounts in orange juice, breakfast cereal, cereal bars, and even margarine.
That’s all for now, folks. Stick around for Part Two of the post where I’ll chat some more about nutrients of concern including Omega-3 fat (not a micronutrient, but still worth discussing), vitamin A, zinc, and more! Thanks for reading! Lindsey
And a quick note from Sarah:
Thanks for the wealth of fabulous information, Lindsey!
OK, so you’ve decided you’re going to take a vitamin or mineral supplement. What now? There are approximately 1.2 billion options out there (only kind of kidding), so how can you make the most informed decision while selecting the highest quality supplement? To begin, because there is so little regulation in the vitamin/mineral industry, it’s always important to be sure your supplement has gone through legit third party clinical testing. Several organizations offer quality testing, such as ConsumerLab, U.S. Pharmacopeia and NSF International. Once you’ve verified your brand’s claims are true, you can move on to reviewing ingredients. Try to avoid artificial colorings (Blue2, Yellow6Lake, Red40Lake), fillers and GMO’s if possible. (Common supplement GMO’s might be glycophosphate, maltodextrin or soy lecithin). My biggest concern with GMO’s in supplements pertains to the unknown presence of allergens, not to mention potential environmental concerns. Lindsey and my RD approved favorite brands include Metagenics as well as Rainbow Light and Care/of (all of these are derived from real food ingredients, always a win!).
Credits // Author: Lindsey Kelsey with contribution from Sarah O’Callaghan. Photo by: Emma Chapman.
References not linked: 1. 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. 2. Gröber, U. (2009). Micronutrients: Metabolic Tuning – Prevention – Therapy. Stuttgart, Germany: Wissenschaftliche Verlagsgesellschaft mbH. 3. Heaney, R. P. (2004). Functional indices of vitamin D status and ramifications of vitamin D deficiency 1– 4. The American Journal of Clinical Nutrition, 25, 1706–1709. Retrieved from http://ajcn.nutrition.org/content/80/6/1706S.full.pdf+html. 4. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. (2011). Evaluation, treatment, and prevention of vitamin D deficiency: An Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism.