The benefits of a plant-based diet are hard to ignore. Research shows that vegetarians typically have lower body mass index, lower total and low-density lipoprotein cholesterol levels, and lower blood pressure.
Compared to non-vegetarians, vegetarians have lower rates of death from ischemic heart disease and decreased incidence of hypertension, stroke, type 2 diabetes, and certain cancers. (1)
Based on all of this compelling evidence, more and more people are switching over to a vegetarian plant-based diet. While a plant-based diet is arguably the healthiest diet in existence, anyone following one must be careful to avoid deficiency in a few key nutrients.
This article reviews that science and, hopefully, will guide vegetarians in mitigating the risks so they can enjoy a healthy and successful vegetarian diet.
Over the years, in my practice, I have treated many vegetarians who become dependent on (and sometimes addicted to) excess carbs and sugars instead of adequate protein, good fat, and fiber. These “unhealthy” vegetarians often experience concerns like dizziness, fatigue, sleep issues, moodiness, cravings, joint issues, and digestive difficulties. These signs are often linked to a mild form of protein deficiency.
Note: I am a strong advocate of a mostly plant-based diet. I believe we should all make it a goal to reduce animal protein down to just 10% of the total diet as the Blue Zone centenarian cultures do. This should be a safe and slow gradual shift. To comprehensively address the concerns listed above (which I fear are the most common health concerns linked to a poorly managed vegetarian diet), I wrote an eBook called The Protein Solution.
6 Common Nutrient Deficiencies of a Vegetarian & Vegan Diet
A plant-based diet requires a proper balance of protein, good fats, fiber, and whole food carbohydrates.
There are a handful of nutritional deficiencies that are common with vegetarians, including vitamin B12, vitamin D, omega-3 fatty acids, calcium, iron, and zinc. (1) All 6 of these are described below.
Anyone following a plant-based diet should be aware of these common nutritional deficiencies and take preventative action to nip any potential issues in the bud.
According to research, 68% of vegetarians and 83% of vegans are B12 deficient, compared to just 5% of meat-eaters. (3)
Signs of B12 deficiency include fatigue, lethargy, weakness, memory loss, cognitive decline, nerve tingling, mood issues, and anemia. (4)
B12 is the only B vitamin that requires a strong production of stomach acid (HCl) to be effectively delivered into the bloodstream. This is why B12 deficiencies are so common. For decades, B12 shots were the gold standard delivery system. Then, dissolvable B12 lozenges were developed—these deliver the B12 directly into the bloodstream and sidestep the weak stomach acid obstacle.
The main function of B12 is to support the nervous system while maintaining healthy brain chemistry and synthesizing neurotransmitters like dopamine, serotonin, and epinephrine. These govern mood, energy, sleep, appetite, drive, motivation, movement, cognition and numerous other brain functions.
The foods richest in B12 are fish, meat, eggs, and dairy, which is why vegetarians and vegans are at such great risk for B12 deficiency. Vegetarian sources do exist, but there are not many of them and, generally, they are not a significant source unless fortified during food production.
One study evaluated the effectiveness of vegetarian sources of B12, such as seaweed, fermented soy, spirulina and brewer’s yeast. They found these B12 sources contain B12 analogs called cobamides, which may block the absorption of the body’s bio-available B12 and increase the body’s need for the nutrient. (5)
Important: Vitamin B12 supports a healthy nervous system in conjunction with folate to manufacture DNA and red blood cells. It also supports the actual volume of the brain, the production of the myelin sheath around the nerves, and the conduction of nerve impulses. >>> Read more about the brain-compromising effects of low B12 levels
B12 with natural folate should be a staple in a vegetarian or vegan diet. >>> Learn more about the right kind of B12 support
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While vitamin D deficiency is incredibly common among non-vegetarians in the US, vegetarians are also at risk.
In one study, non-vegetarians were found to be deficient in vitamin D, and vegetarians were only found to be insufficient in vitamin D. (6) In other studies, vegans and vegetarians were found to be more at risk for a vitamin D deficiency compared to non-vegetarians. (1,7)
The most logical reason for the discrepancy between vitamin D levels in vegetarians and non-vegetarians is that vitamin D is a fat-soluble vitamin predominately found in animal products.
A growing body of knowledge shows that, at optimized levels, vitamin D functions as a hormone rather than a vitamin, with numerous notable effects on the body. These effects include support for healthy immunity, mood, bone formation, skin, heart, glucose metabolism, musculoskeletal comfort, and targeted support for over 2000 genes.
Supplementing with vitamin D in the winter in latitudes north of Atlanta is critical to maintaining optimal vitamin D levels. Vitamin D and magnesium work together to optimize the body’s absorption of vitamin D. The Vitamin D Council suggests a daily intake of magnesium between 490-700mg to maximize the benefits of vitamin D.
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Your goal should be to get your vitamin D levels between 50-80 ng/ml and keep them there. Testing is the only way to know for sure that you are maintaining these levels. Test yourself in the fall when the levels are the highest and in March when they are the lowest. With those two numbers, everyone can safely calculate their vitamin D supplement needs.
Omega-3 Fatty Acids
A study published in the European Journal of Clinical Nutrition found that vegetarians have lower levels of the omega-3 fatty acids found most commonly in fish oils, EPA and DHA.
Optimal levels of EPA and DHA support healthy cardiovascular function and healthy cholesterol levels.
There are healthy vegetarian sources of omega-3 fats, like those found in flax and chia seeds, but these plant-based omega-3 fats are alpha-linolenic fatty acids (ALA) that must be converted into EPA and DHA.
While ALA does convert to EPA and DHA, they do so very inefficiently, suggesting that the benefits derived from flax and chia seeds may not be derived from this conversion.
Vegetarians may want to consider supplementation with a DHA/EPA fish oil supplement. Studies suggest supplementing with about 2 grams per day of EPA, DHA support. (2)
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Calcium is primarily found in vegetables, nuts, seeds, and grains, but the science shows that vegans and vegetarians are still at risk for low calcium levels.
Some studies suggest that oxalates in certain vegetables and phytates in grains may inhibit the absorption of calcium, although other studies argue against this as a cause. (8)
Lacto-ovo vegetarians seem to be not at risk here, as one study showed that leafy greens like kale and spinach have high amounts of calcium. As we saw with B12, the efficiency and strength of the digestive system can determine whether the calcium from your leafy greens are being delivered into the bloodstream. In cases where digestion is weak, calcium supplementation may be needed. >>> Learn more here
One study suggested that one 8-ounce glass of milk has the same calcium as 16 servings of spinach. (8)
Studies like this are often used to advocate the need for animal protein, however, I believe that the key to proper mineral absorption lies in the efficiency of digestion.
While many people become vegetarian for ethical reasons, many choose to do so because they struggle with digestive issues from eating the standard American diet. Becoming a vegetarian may eradicate your digestive symptoms, but it will not fix the potential underlying digestive imbalance that could be linked to deficiencies many studies attempt to link to the vegetarian diet itself.
As a maintenance strategy for your bones, it is important to get and maintain 1000-1200mg of calcium per day in your diet. The benefits of calcium are greatly enhanced with optimized vitamin D3 levels.
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Iron, like calcium, is found to be a problem for many vegetarians. Most commonly, the storage of iron in the form of ferritin is lower in vegetarians than non-vegetarians. (9)
If you get an annual blood test, be sure to add ferritin levels to the list of checked factors. Iron is a standard item on most blood tests.
Vegans seem to be most at risk here. In one study, 40% of vegans were deficient in iron even with their reported intake at above the recommended levels. (10)
So, we ask the question, “What is inhibiting iron absorption in vegetarians?”
Excess tea, coffee, and dairy can block iron absorption, so these foods should be taken in moderation. Grains, which are high in phytic acid, have been blamed for iron deficiencies, yet cultures who have high-grain diets do not have iron deficiencies—in fact, their iron levels are higher than average.
Again, I suggest we evaluate the amount of processed food and sugar in the diet and troubleshoot every aspect of the digestive process to get to the bottom of deficiencies like these.
If you are a vegetarian, make sure you get regular blood tests to evaluate these possible deficiencies.
The foods highest in iron are liver, fish, tofu, iron-fortified breakfast cereals or bread, eggs, pulses and beans, nuts and seeds, dried fruit (dried apricots, prunes and raisins), whole grains, leafy greens, and molasses.
Vegetarian diets often include ample amounts of zinc, however, studies suggest vegetarians seem to be at a greater risk of becoming deficient in zinc.
Phytates, commonly found in plant foods, may reduce zinc absorption. While the cause of the zinc deficiencies caused by phytates is hotly debated in the science world, the reality is that vegetarians are at risk here. One study even suggested vegetarians may require up to 50% more dietary zinc than non-vegetarians to make up for the lack of absorption. (11)
Zinc deficiency has been linked to weakened immunity, impaired cognitive function, behavioral problems, impaired memory, learning disability, and neuronal atrophy. (12)
Proteins increase zinc absorption, so legumes and nuts are great choices to increase your zinc.
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If you are a vegetarian, make sure you get regular blood tests to evaluate these possible deficiencies.
While mineral deficiencies may be somewhat greater for vegetarians, non-vegetarians are also at risk for mineral deficiencies. Mineral deficiencies are a concern for all Americans, as the minerals in the soils here have been depleted for decades.
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Many who read this article may be enjoying all the amazing health benefits of a vegetarian diet. I write this article not to condemn vegetarianism in any way.
On the contrary, I am a whole-hearted believer in a diet that is at least 90% plant-based as this is the diet. This is, after all, the diet that centenarian cultures (people who live past the age of 100) are found to eat!
If you are not already a vegetarian, consider lowering your animal consumption slowly, making your goal to make only 10% of your diet animal protein.