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Is a vegetarian or vegan diet better for you? Part 1

By Dr. Rehan Lakhani, ND

It might be time to rethink your vegetarian/vegan diet.

As a naturopathic doctor, I get this question a lot. It has many strong opinions associated with it, and often goes deeper than just which foods to consume. Moral, ethical, and environmental implications have been explored amongst most vegetarians and vegans that I meet.

There are a variety of reasons for why someone might choose to consume a vegetarian/vegan diet, including environmental and ethical reasons. It is completely understandable and respectable to make decisions based on the social, economic, environmental, and moral impact of food.

Individuals go through their own journeys around these issues, and each of us end up with different answers, and very different reasons for making the food decisions that we make on a daily basis. That doesn’t mean that one way of eating is “better” or more righteous than the other, but that everyone values and weights the factors associated with this decision differently and will come to their own individual conclusion.

Strictly from a nutritional standpoint however, many people associate vegetarian/vegan diets as being healthier than their omnivorous counterparts. The intent of this article is to look at the research behind this association, and give us answers as to whether or not this dietary choice is optimal for our health.

Missing nutrients in a vegetarian/vegan diet

While fruits and vegetables contain a wide variety of vitamins, minerals, and phytochemicals, there are quite a few nutrients that are lacking in vegetarian and vegan diets. Let’s discuss what they are.

Vitamin A

Most of us know that vitamin A is incredibly important for vision, but did you know that it’s also critical for proper immune function, bone health, and maintenance of your skin and internal mucus membranes? Vitamin A also helps your cells replicate and grow, replacing damaged or old cells in your body. While vitamin A deficiency is rare in developed countries, it can happen if you have a malabsorption condition like celiac disease or cystic fibrosis, and under-nutrition (which is very likely in vegetarians and vegans).

One of the first signs that you might be low in this vitamin is losing your ability to see in dim light or at night (nyctalopia), drying, scaling, and thickening of the skin (keratinazation), including in the respiratory tract, which can lead to frequent infections like colds and flu. Lastly, your immune system is not able to function as well as it could be, leading to more frequent illness and infections (1) .

Small amounts of vitamin A can be derived from plants in the form of beta-carotene, but this form is not converted well to vitamin A in the body (2). This means that you would have to consume many servings of vegetables containing beta-carotene to get your daily recommended amount of vitamin A. Vegetables that contain a large amount beta-carotene include (3):

  • Sweet potato
  • Spinach
  • Carrots
  • Pumpkin
  • Kale
  • Black eyed peas
  • Broccoli

Vitamin D

Vitamin D helps us absorb and regulate levels of calcium and phosphate in the body, and without adequate vitamin D, bones can become thin, break easily, or can be deformed. Osteoporosis is a condition that can develop as a result of long standing vitamin D deficiency. There is also emerging evidence showing adequate vitamin D status could affect cancer risk, particularly in reducing the risk of colon cancer (4). Vitamin D also plays an active role in modulating cell growth, immune function, and reducing overall inflammation.

Factors that can impact your ability to absorb or synthesize vitamin D are (5):

  • Age: the older you get the less efficient your body gets at synthesizing vitamin D
  • Northern climates and limited sun exposure
  • Darker skin
  • Inflammatory bowel disease (ulcerative colitis and Crohn’s), or other conditions that interfere with fat absorption
  • Obesity and gastric bypass surgery

The form vitamin D that your body needs, D3, is almost always found in animal sources of food like eggs, seafood, organ meats, and dairy. Some mushroom species do contain some vitamin D (maitake, portobello, and chanterlle), and the best way for vegetarians and vegans to get this vitamin is either through those mushrooms, fortified foods, or lots of sunshine.

The amount of vitamin D in these sources varies significantly, and again, can deliver a lot less than what would be considered adequate for the maintenance of good health and disease prevention. The best way to ensure you get enough is through D3 supplementation.


When you measure serum (blood) levels of iron in vegetarians and omnivores, often times they are very similar. When ferritin levels are measured however, vegetarian and particularly vegans tend to be more deficient than omnivores. This is an important finding because ferritin is a measure of iron storage, meaning that many vegetarians and vegans are dipping into storage for their iron requirements. This is often why we see iron deficiency and anemia take time to develop in people following these diets – especially if they are women.

Now, there are many, many sources of plant based iron, but the form of iron that is in plants is very difficult for humans to absorb. Non-heme iron (plant based iron) has a chemical structure that our body has to change before it can be fully absorbed, and that absorption is also impacted by the composition of the other foods you have eaten at the same time. For example, coffee or tea can inhibit iron absorption. Heme iron on the other hand is much easier to absorb regardless of the aforementioned factors.

While iron deficiency anemia does take a long time to develop, you can prevent it from happening by supplementing with iron to ensure you are getting enough from your diet without having to dip into your ferritin stores.

Symptoms of iron deficiency anemia include (6):

  • Fatigue and weakness
  • Headaches
  • Rapid or irregular heartbeat
  • Shortness of breath or chest pain
  • Pale skin


B12 is probably the most common deficiency we associate with a vegetarian or vegan diet. This vitamin is responsible for making red blood cells, so long standing B12 deficiency can result in anemia because there aren’t enough red blood cells in your body.

Deficiency in B12 can cause fatigue, weakness, trouble concentrating or focusing, numbness, tingling or muscle weakness, and many other symptoms. Additionally, there is research linking B12 deficiency to psychiatric illness as well (7).

B12 (and other B vitamins) are also required to convert an amino acid called homocysteine into one called methionine. This is incredibly important because if homocysteine builds up in the body, it can lead to an increased risk cardiovascular and neurodegenerative diseases (8).


Vegans are more likely to be deficient in calcium than their vegetarian or omniverous counterparts. Leafy greens certainly contain high amounts of calcium, but it is difficult for your body to absorb it from these sources because of the fibre, oxalic, and phytic acid content of plant based calcium sources (9).

Combining different plant based sources of calcium might help with better absorption, but it would still be difficult to determine if you are getting enough.

We know that calcium is important for bone health, but it’s also important for cardiovascular health, and muscle function (10, 11), making this an important mineral to get from your diet.


Zinc is involved in metabolism, DNA replication and repair, the immune system, and so much more. Vegetarians would have to consume 50% more zinc than the daily recommended value because vegetarian sources of zinc are more difficult for the body to absorb. It is possible to get adequate amounts of zinc from a vegetarian diet if a large volume of fruits, vegetables, grains, and dairy are consumed, but it is more difficult for someone on a vegan diet to get appropriate amounts.

Effects of lower zinc intake include frequent colds and flu, delayed healing of cuts and other wounds, loss of appetite, age related macular degeneration, and for pregnant mom and children, impaired growth (12).

Foods that contain zinc include:

  • Beans – pinto, chickpea, kidney
  • Pumpkin seeds
  • Fortified grains and cereals
  • Yogurt and milk
  • Almonds (12)

As you can see, there are many nutrients that you need to be concerned about when on a vegetarian or vegan diet. These are just some of them – stay tuned for part 2 of this article where we will discuss which micronutrients are missing in vegetarian and vegan diets.

If you’ve been on one of these diets for an extended period of time, and are experiencing low energy, trouble focusing or concentrating, digestive upset, or skin conditions, book a free consult to discuss which nutrients you might be depleted in, and how to safely restore them to their appropriate levels.

Questions or comments? Let me know below!

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