Many people don't know that B12 isn't made by plants or animals. This vitamin is made by bacteria that live in water and soil. Due to the modern era's sterile practices, the microbes, and the B12 they produce, are gone. So when people think meat is rich in B12, that's because these animals receive B12 supplementation before being slaughtered. So although we don't get much B12 from our foods or water sources, we don't get infectious disease either, a fair trade off, since B12 is readily available in supplement form.
I suggest that anyone on a plant-based diet take a cyanocobalamin supplement. I take a 1000 mcg 2-3 times per week, knowing that more than I need will get absorbed. Your body needs about 2.4 mcg per day, and can store it for extended periods and release small amounts when needed. It's also water soluble, meaning that we can excrete excess amounts in our urine, making toxic overloading pretty darn rare.
B12 deficiency can cause a wide range of symptoms, from general malaise, fatigue, brain fog, anemia, and neurological symptoms. When in doubt, simply get your blood B12 levels checked by your health care professional.
Vitamin D is a steroid-like hormone that's produced from precursors in our skin that are transformed when in contact with UV light coming from the sun. Since we don't spend much time under direct sunlight anymore, most of us are deficient in Vitamin D. Our office jobs under artificial lights are a far cry from the sunlight our tropical ancestors evolved with. Although many dairy and non-dairy milks are fortified, not everyone consumes them reliably. Vitamin D deficiency can be easily diagnosed by testing blood levels of 25-hydroxy-vitamin D and symptoms can range from subtle fatigue to depression, muscle pain and weakness all the way to increases in risks of chronic disease later in life.
Although some will have sufficient exposure to direct sunlight, others will want to supplement as an insurance policy, and to decrease cancer risk, as seen with supplementation. I suggest a daily vitamin D supplement of 2000 IU daily. On the plant-based diet, you can also find fortified non-dairy milks and yogurts, as well as other sources of vitamin D, like oranges, oatmeal, tofu and mushrooms.
Some advocate for a 10000 IU supplement once per week, I personally take 2000-4000 IU when I think about it 2-3 times per week. Up to 4000 IU per day have been considered to be the safe upper limit, but doses up to 10000 IU per day have not been shown to cause toxicity in the short term, but don't seem to provide any additional benefit.
Iron anxiety is second only to protein panic for people on a plant-based diet, but there's no need to worry. Although vegans do have lower iron stores than meat eaters, that could be a good thing. First of all, studies do not show increases in the rates of anemia in vegans, and secondly, lower iron stores (in the lower but normal range) have been linked to decreased risk of heart disease and cancer. Just so happens that iron (especially heme-iron found in animals) tends to be highly inflammatory once oxidized, much more than non-heme iron, which is the type of iron found in plants. It is well known that heme iron from animals is better absorbed than non-heme iron from plants, but that might confer a natural protection against iron overload, which is known to be inflammatory.
Iron won't be an issue on a well planned plant-based diet. Like other vitamins and minerals, blood levels can be checked by talking to your doctor. To make sure you're getting sufficient iron, make sure to include the following iron rich foods:
Legumes, like lentils, soybeans, tofu, tempeh, lima beans
Grains, like quinoa, fortified cereals, brown rice, oatmeal
Nuts and seeds, like pumpkin, cashews, pine, squash, pistachios, sunflower
Vegetables, like collard greens, swiss chard, tomato sauce
Others, like blackstrap molasses, prune juice
Multiple factors will affect iron absorption:
Taking in iron with vitamin C rich foods (like oranges, lemon, or other fruits) will increase absorption dramatically
Smaller frequent doses are absorbed much better than single large doses
Tannins in coffee and tea will decrease iron absorption, so try to separate both by 1-2 hours
Iodine plays a major role in thyroid hormone synthesis and thyroid hormones pretty much control most of the body's metabolic functions. Iodine is difficult to find in foods, due to the poor quality of today's modern soils. They still exist in certain seaweeds, like kelp, but not many people consume adequate amounts. Cranberries and potatoes have unreliable sources of iodine largely depending on the soil's levels. Table salt is iodized, meaning fortified, but we already eat too much salt in our western diets, and salt is linked to increases in blood pressure, heart disease and stomach cancer, and should be kept to 1500 - 2300 mg per day. 3/4 of a teaspoon of iodized table salt per day will give you all the iodine you need.
If you avoid table salt, remember that the alternatives, like pink salt, sea salt or pink Himalayan rock salt, aren't iodized. Also try eating more marine plants, or you could consider supplementing. The recommended daily dose is 150 mcg for both sexes.
If you've never heard of K2, you're normal. We are just recognizing its role in calcium metabolism, by preventing blood vessel calcium deposits, or calcifications, that contribute to heart disease. Vitamin K1 is plenty abundant in a plant-based diet, but K2 is mostly found in animal foods like butter or egg yolks. There is some K2 in fermented foods, but not enough to serve as a reliable daily source. We suggest a daily supplement of 10-25 mcg. Official recommendations for daily K2 intake aren't even available yet, but studies show additional benefits when consuming 10-45 mcg per day, independent of K1 intake.
Zinc serves as a co-factor in many biochemical reactions. It contributes to the proper function of multiple enzymes. Plants have plenty of zinc, but it's poorly absorbed because of the phytate content of plant foods. Phytates seem to partially hinder zinc absorption. Experts recommend that vegans increase the recommended daily intake by 50% to compensate for lower absorption, but this shouldn't be a problem if you're eating enough calories from a variety of plant foods. You can also decrease phytates in the foods you eat by cooking your grains, soaking your nuts or sprouting your beans.
The recommended daily intake is 11 mg for men and 8 mg for women. If you're concerned about your zinc intake, you can get your blood levels checked, or you can supplement with 150% of the RDI, which gives 12-20 mg. Doses up to 40 mg per day have been deemed safe, but no added benefits appear after 15-20 mg per day.
Magnesium and Selenium
Thanks to soil depletion, these two minerals are now found in much lower concentrations in the plant foods that used to carry them and they're often deficient in the diets of carnivores and vegans. If you think you should supplement with magnesium, we suggest taking 150-200 mg per day. One Brazil nut a day is enough to get all your selenium requirements, or you can supplement with a daily dose of 30-50 mcg.
My micronutrient management plan.
I started my plant-based transition by downloading Cronometer on my smart phone. I logged my food intake here and there for a few months. With the app, you'll be able to monitor macros and micronutrients, like vitamins and minerals, in order to then make the adjustments required either through food or supplementation.
Phytonutrients are chemicals that are found in plants. These special compounds help plants defend themselves against germs, fungi, bugs and diseases. It's no surprise that these benefits would get transferred to those who eat them. Although phytonutrients aren't essential to stay alive, unlike like macro and micronutrients, they do help you to fight off infections and offer an insurance policy against chronic diseases.
There are 6 different types:
carotenoids (think carotene in carrots, or lycopene in tomatoes)
ellagic acid (think strawberries and raspberries and their cancer fighting properties)
flavonoids (they give green tea its super powers in preventing disease)
resveratrol (think the cardio-protective properties of red wine)
glucosinolates (think cruciferous vegetables, like sulforaphane in broccoli)
phytoestrogens (think soy and cancer protection or protective lignans in flaxseeds)
If these compounds naturally protect plants from the damaging effects of direct sunlight, help prevent disease and its spread, and help them survive the constant onslaught of bacteria, fungi and other pests, just imagine what they're capable of accomplishing inside us. We evolved with their consumption, for millions of years. They are only in plants, and they're just another one of nature's reasons for increasing the amount of plants in your diet.
In this section, we've reviewed vitamins, minerals and phytonutrients. In terms of vitamins, due to reasons explained earlier, I'm extra careful of finding foods rich in vitamin B12 (like fortified non-dairy milks and nutritional yeast). I also make sure to get direct exposure to sunlight in the form of physical activities outdoors to make sure my body produces vitamin D, even if I know I can find it in fortified foods. As an insurance policy, since I've stopped monitoring and logging my food intake in my Cronometer app, I still take a supplement of B12 and vitamin D. Mine is a vegan supplement by herbaland containing both B12 and D3 (1000mcg and 1000 IU respectively). Knowing it would take gross negligence to overdose on these supplements, I take 1-2 gummy bears 2-3 times per week.
In terms of iron, I don't take any supplements. Even after years on a fully plant-based diet, my blood work is great and I simply don't need them, since I eat lots of various iron-rich foods, like lentils, beans, cacao powder, tofu and spinach. I still use iodized table salt although in a perfect world, I'd stop that, but hey, I'm just not there yet. I do take a "multivitamin", but not for the vitamins, since I get plenty of them through my diet, more for the trace minerals, like zinc that our body absorbs less because of phytates in plants. I eat Brazil nuts regularly and get my selenium that way.
As for phytonutrients, they are nature's own defense mechanism against the harsh environment that plants live in. Although they aren't required for survival, like carbs, protein and fat, they are required for optimal health. There are 6 different classes of these disease fighting super chemicals, and all we need to do to get them is to eat plants.