According to the Academy of Nutrition and Dietetics, plant-based diets can promote health in all stages of human life. Research shows that vegans, vegetarians and people who consume low amounts of lean meat have a lower risk of heart disease, hypertension, type 2 diabetes, stroke, obesity and cancer.

Excluding or reducing meat from your diet is not only good for your health, it also helps the environment. Plant-based diets require fewer resources, especially water and fossil fuel. And, they also have much less of an impact on global warming.

In terms of ethics, vegetarians and vegans are opposed to killing animals for food. However, many vegetarians consume animal by-products such as milk and eggs and vegans exclude all animals and their by-products.

Although healthy, plant-based diets need to be planned in order to avoid nutrient deficiencies and long-term health problems. Vegetarians and vegans who are not careful can suffer from a lack of protein, Vitamin B12, Vitamin D, iron, calcium, iodine and Omega-3 fatty acids.

If you are vegan or vegetarian and you are concerned, you should see a registered dietician or medical professional specialized in nutrition. Meanwhile, here are five key nutrients to which you should pay attention:

Vitamin B12

Vitamin B12 is critical for human function and is not found in any plant foods. Some types of algae may contain B12 – for example, spirulina – but this type of B12 isn’t as reliable a source as the type derived from animal sources.

Vegetarians and vegans should not rely on algae or spirulina for Vitamin B12. It is better to obtain Vitamin B12 through supplements or B12-fortified foods. Blood test results can help determine B12 levels and whether there is a need for supplements.

Protein

Protein is critical and vegans don’t get any animal protein. A lack of protein in your diet will affect bone health and muscle mass. Although spirulina isn’t a good source of Vitamin B12, it is protein-rich and an excellent source of amino acids, vitamins and minerals, including iron and calcium.

Spirulina is a blue-green algae and is 100% natural.

Other plant foods that are good sources of protein include:

1. Soybean-based foods: tofu, tempeh, edamame, soy milk.
2. Legumes: lentils, kidney beans and chickpeas.
3. Ancient grains: quinoa, farro, amaranth.
4. Seeds: hemp and chia seeds.
5. Wild and black rice.
6. Nuts, nut butters or nut milks.

Vitamin D and calcium

If you don’t consume eggs, fish, milk or dairy foods, you need to find alternative ways to get Vitamin D and calcium in your diet. Vitamin D supplements may be necessary.

If you’re getting enough sun exposure or if you eat foods that are Vitamin D fortified, you might not need to supplement. Some foods and beverages, such as tofu, soymilk, fruit juices and dry cereals, are fortified with Vitamin D. Check the nutritional information on the containers.

As for calcium, vegans and vegetarians have the same calcium requirements as omnivores and should meet the daily intake of 1000 mg/day (ages 19-50) and 1200 mg/day (elderly). Leafy green foods with low levels of oxalic acid are good sources of calcium. Examples of calcium-rich leafy greens are kale, broccoli, turnip greens, mustard greens and bok choy.

In general, the higher the oxalic acid content of a plant food, the lower the rate of calcium absorption. Spinach provides calcium, but its bioavailability is poor due to its high oxalic acid content.

According to experts, you have to eat plenty of leafy greens to get the same absorbable calcium found in one serving of milk, cheese or yogurt. For example, 4½ servings of broccoli, 2½ servings of bok choy, 3 servings of kale or 16 servings of spinach.

It is best to obtain calcium from natural food sources. For a list of plant foods high in calcium, see here and here.

Because calcium is added to many foods, be careful not to get more that the recommended dosage, especially if you also take a supplement. High doses of calcium increase the risk of kidney stones and can interfere with certain drugs, such as corticosteroids and thyroid hormones. Soy and tofu products, nut milks, fruit juices and cereals can be fortified with calcium.

Regular physical exercise combined with a diet that is protein-rich and with an adequate amount of calcium and vitamin D will help keep your bones strong and healthy and reduce the risk of osteoporosis.

Iron

Red meat isn’t the only iron-rich source. To prevent iron deficiency anemia, vegans and vegetarians need to combine non-heme foods (plant foods high in iron) with foods that are high in Vitamin C. Pairing foods this way will enhance the absorption of iron in your body.

Examples of non-heme foods are dark-leafy greens (spinach, romaine, kale), lentils, kidney beans and other legumes, dried fruits and iron-fortified foods, like tofu and cereals. Foods high in Vitamin C are peppers, tomatoes, cauliflower, citrus fruits, berries and brocoli.

Add oranges or grapefruits to your lentil and kale salads. Have a fruit salad with your iron-fortified cereal. Eat vegetarian dal, chili or stir fries with peppers, tomatoes, lentils and/or kidney beans all served with black rice or quinoa and a green salad or tomato salad is a complete meal and it will give you the iron that you need.

As much as possible, try to get your iron from food sources instead of pills. In addition to its high protein, essential amino acids, minerals and vitamins, spirulina also has lots of natural iron.

If you take spirulina, choose a brand that is organic and comes from a reputable source. Some types of spirulina are grown in an uncontrolled environment and may contain heavy metals and other toxins. Pregnant or breast-feeding women, people with autoimmune conditions, phenylketonuria (PKU) or on anti-coagulation medication should consult a doctor before taking spirulina.

Photo: James Sutton