Vegetarian and Vegan Diets - Nutrients Dietitians Think About

Authors: Lucie Liang, McGill dietetics student & Sophia Zheng, registered dietitian

Disclaimer: The opinions expressed in the following article are those of the author(s), and do not necessarily reflect those of Foodoc.

Vegetarian or vegan diets are keywords in the news these days. Food industries are swept by this wave, and plant-based products are never easier to find. Among the benefits of the plant-based diet, the ones related to health are certainly the most attracting, like lower risk of cardiovascular disease, hypertension, obesity, etc. However, necessary knowledge and effort are required to benefit from this diet.

If you are thinking about transitioning to vegetarian or vegan diet, you must be thinking what are the nutrients I should be cautious of, and how to prevent deficiency?

Protein

Plant-based diet could be classified by different restriction levels. For people who still consume egg and dairy products (lacto-ovo-vegetarian), the risk of protein deficiency is lower. In contrast, those who eat strictly non-animal products (vegan) should pay more attention to the protein content of their meals. Protein is an essential building block of all the body tissues, and its deficiency could lead to fatigue, weakness during exercises, hair loss and trouble concentrating and sleeping.

Plant-based sources of protein are abundant, but their qualities vary a lot. Proteins are made of amino acids, and high quality protein has the composition and ratio of amino acids that our body needs. Proteins from plant-based foods have lower quality than those from animal sources, but having a variety of protein-rich foods could contribute to a more ideal amino acid composition. Foods rich in protein include dairy products, egg, soy, beans, lentils, nuts and seeds.

Iron

This is one of the most famous nutrients among followers of plant-based diets. There are two forms of iron: heme and non-heme. Heme iron is more absorbable and better used by our body, but it’s mostly found in meat, poultry, and fish. Non-heme iron, which is found in many vegetables, is much harder to be used by us. Lack of iron in the long term may lead to iron deficiency anemia, and its symptoms include feeling tired, looking pale, shortness of breath and cold hands and feet. However, when anemia is mild, these symptoms are hardly noticeable.

Vegetarian foods rich in iron include fortified cereals and flour, cream of wheat, legumes, pumpkin seeds, almonds, tofu, leafy green, potatoes with skin and plum. As most naturally found vegetarian sources provide non-heme iron, different techniques could be used to increase its absorption:

Including foods rich in vitamin C in the same meal, such as bell pepper, citrus fruits, tomatoes, strawberries, kiwi, cantaloupe, and vegetables of the cabbage family.
Excluding coffee, tea, and foods rich in calcium from meals as they reduce iron absorption. Consume them between meals.
“Lucky Iron Fish”: this product is a small fish-shaped cast iron ingot used to provide iron supplementation. By placing the “fish” into boiling water, elemental iron can leach into water and foods. The price is affordable, and the quality can last up to five years.

Zinc

This nutrient is less known but very important to consider for vegetarians and vegans. Phytate, a compound commonly found in plant foods, reduces the absorption of zinc. Therefore, higher zinc should be consumed to ensure adequate level in our body. Even though we need this mineral in a small amount, it plays a very active role in our body. Zinc supports growth and development as well as strengthens the immune system. Poor wound healing, easy to get sick and dermatitis are all typical symptoms of zinc deficiency.

Good plant sources of zinc include legumes, nuts, soy products and wheat bran cereal. Avoid taking calcium supplement too close to a zinc-rich meal as the two minerals compete for absorption. In addition, leavened bread and fermented soy products (tempeh and miso) could enhance absorption¹.

Vitamin B12

Since this vitamin is only naturally found in animal products, vegans are at the highest risk of vitamin B12 deficiency. Very low intake could lead to anemia, heart disease, and nerve system damage.

Dairy products, eggs, fortified cereals and nutritional yeast are the most known vegetarian sources.

Vitamin D

By working with calcium, this sunshine vitamin promotes optimal bone health. Like vitamin B12, vitamin D is rarely naturally found in plant-based foods. Sunlight is not a promising source in Canada. Especially for vegan, fortified foods or supplements are needed to avoid weak bones and muscles.

As milk in Canada is fortified with vitamin D, it becomes one of the best sources. Egg yolk is also an excellent source. For those who consume strictly plant foods, mushrooms, fortified almond and soymilk, fortified cereals are all very helpful.

Other Important Points

Even though many restaurants and food industries offer vegetarian options, not all of them are healthier. We should still be cautious about the protein, carb, fat and fiber content of meals as many vegetarian options are lower in protein, higher in carb and fat, and even less nutritious than non-vegetarian foods. Your diet should be restricted in high-fat and high-sugar foods. A plant-based diet is not only eliminating foods from animal sources, but also means selecting nutritious and diverse food items wisely.

The Journal of Nutrition, Volume 130, Issue 5, 1 May 2000, Pages 1378S–1383S,https://doi.org/10.1093/jn/130.5.1378S