Ensuring that you're getting sufficient nutrients while on a plant-based diet is a contentious subject. Many people believe that there's no way that a diet without animal products can be complete while others believe plant-based is nutrient-dense, and therefore healthiest.

Here, Natalie Rizzo, a New York-based Registered Dietician, tells you how to know that you need to try taking a supplement to boost your energy, mood, and overall wellbeing.

Q: Sometimes I feel I am doing so well and my energy is good but then even with the same diet or just slightly different I get so tired. Could I be deficient in something? How do I know?

A: One of the most common complaints I hear from those who are new to plant-based eating is a lack of energy. This is especially true among fitness enthusiasts since they often are used to burning more calories and sweating out more electrolytes. Many people turn to plant-based eating because they think it will make them feel healthier overall, but then they are disparaged when instead, for a few weeks, they feel lethargic. After all, plant foods like vegetables, fruit, nuts, seeds, legumes, and whole grains are full of vitamins, minerals, and antioxidants, so shouldn’t they give you an energy boost?

If you’re doing it well and avoiding junk food like chips and candy (technically you can be vegan and eat sugar all day long), a whole food plant-based diet should make you feel great and enhance your energy levels. But if you’re not paying attention to getting enough of the right nutrients, you may end up with a deficiency that will zap your energy.

Handful of Vitamins
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Do you have a nutrient deficiency?

There are certain nutrients you need to pay close attention to on a plant-based diet. Iron and Vitamin B12 are found in meat and dairy, which makes it harder for someone to get on a strictly plant-based diet. But nowadays even plant-based foods are enhanced and infused with these two must-have essential vitamins and minerals, so whether you are using non-dairy creamers or milk, many of them are fortified.

That doesn’t mean you can’t get these nutrients on a plant-based diet, it just means that you need to pay closer attention to the foods you choose. Let’s take a closer look at these nutrients.


Iron is a mineral that is necessary for the formation of hemoglobin, a protein that delivers oxygen throughout the body. It plays a crucial role in energy metabolism, and working muscles need iron to function properly.  Therefore, low levels of iron can cause side effects, like extreme exhaustion, dizziness, headaches, and frequent infections.

The reason that plant-based eaters need to be more cautious about iron is that there are two types–heme and non-heme. Heme iron comes from animal foods, and it’s the type of iron that is most easily absorbed by the body. Non-heme iron comes from plant-based foods, and it’s not as well absorbed by the body.

A review of 27 studies showed that vegetarians are more likely to have lower iron stores compared with non-vegetarians. That said, the authors noted that since high iron stores are related to high animal food intake, those who eat more iron have an increased risk for certain diseases, such as type 2 diabetes. Therefore, the study authors recommend that all types of eaters should consume more plants to control their iron status.

If you think you may have an iron deficiency, ask your doctor to do a simple blood test. They can assess iron status very quickly through a blood draw and advise you on the right supplemental dose to take. Iron is a mineral that can be dangerous in high amounts, so do not take a supplement unless you’re deficient. It also never hurts to eat more of these iron-rich foods. 

Vitamin B12

Another deficiency that can wreak havoc on your energy is Vitamin B12.  This nutrient plays a role in converting food into glucose to provide energy for exercise, as well as the nervous system, blood, and bone health.

Vitamin B12 is made by microorganisms in the animal’s intestines or diet, which is why the most prevalent sources come from animal foods. Humans are not able to make their own Vitamin B12, and the same goes for plants. Some fermented plant foods, like tempeh, have Vitamin B12 because the bacteria used to make the food also produces the vitamin. But generally, plant foods are naturally lacking Vitamin B12.

That said, many manufacturers fortify plant foods with this vitamin so that plant-based eaters can get enough. Most plant-based milk, breakfast cereals, faux meats, nutritional yeast, and even some grains are fortified with Vitamin B12.

A review of the literature found that Vitamin B12 deficiencies among plant-based eaters can vary wildly. The researchers observed a deficiency range of 0 to 86.5% among adults, with higher deficiency prevalence in vegans than vegetarians.

Luckily, assessing a B12 deficiency is easy as well. Ask your doctor to do a blood draw to determine if your Vitamin B12 blood levels are high enough. If you’re deficient, you may have to get Vitamin B12 injections or take a sublingual B12 supplement to get your levels back up to normal.

Other reasons you might be tired

Of course, there are other reasons you may be tired all the time like you’re exercising constantly and not giving yourself rest days to recover properly. Or maybe you’re not getting enough sleep or you’re drinking too much alcohol, which can interfere with sleep. Whatever the cause, it’s important to consult with a healthcare professional to figure out what’s really going on. If it is diet-related, a doctor or Registered Dietitian should be able to help.

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