Vegetarian and vegan diets can offer numerous health benefits. Nguyen Trung Hieu, a specialist in the Department of Dietary Therapy at Tam Anh General Hospital in Hanoi, notes that vegetarians often have lower body mass indexes, total cholesterol, LDL (low-density lipoprotein) cholesterol, and blood pressure compared to non-vegetarians. As a result, vegetarians have a reduced risk of obesity, heart disease, high blood pressure, stroke, and type 2 diabetes.

However, an unbalanced vegetarian diet that completely eliminates animal products can lead to deficiencies in essential micronutrients. Vegetarian diets typically focus on vegetables, fruits, grains, nuts, and legumes. These foods are rich in fiber, antioxidants, and many B vitamins, but they lack or contain limited amounts of nutrients found primarily or solely in meat, fish, eggs, and dairy.

Hieu cautions that micronutrient deficiencies don't appear overnight but accumulate gradually over time. Early signs like fatigue, hair loss, memory decline, pale skin, or numbness in the extremities are often overlooked. If not detected and addressed promptly, prolonged micronutrient deficiencies can affect the immune, endocrine, cardiovascular, and nervous systems, as well as reproductive health. Here are some nutrients that are commonly deficient in vegetarian diets:

Vitamin B12

Vegans are at high risk of B12 deficiency if they don't supplement appropriately. Vitamin B12 deficiency can cause anemia, persistent fatigue, sensory disturbances, memory impairment, and peripheral nerve damage. In pregnant women, B12 deficiency can affect fetal brain development, increase the risk of neural tube defects, and cause anemia and weakness. Vegetarians can supplement B12 through fortified foods like plant-based milk, breakfast cereals, nutritional yeast, or supplements as prescribed by a nutritionist or doctor.

Iron

Iron is crucial for blood production, oxygen transport, and energy metabolism. Iron deficiency can lead to persistent fatigue, dizziness, pale skin, rapid heartbeat, nausea, and anemia.

Plant-based sources of iron include lentils, soybeans, leafy green vegetables, pumpkin seeds, and whole grains. However, iron from plants (non-heme iron) is less readily absorbed than iron from animal sources (heme iron). The absorption of non-heme iron can be hindered by phytic acid and polyphenols, which are present in the same plant foods rich in iron.

To enhance iron absorption, consume iron-rich foods with vitamin C-rich foods like oranges, pineapples, tomatoes, and bell peppers. Limit tea, coffee, or calcium-rich foods during meals containing iron, as they can inhibit iron absorption. Individuals with severe iron-deficiency anemia should take iron supplements as prescribed by a doctor.

A vegetarian diet should include a variety of foods to avoid nutrient deficiencies. Illustrative photo: Hanh Quyen

Calcium

Calcium maintains strong bones and teeth, regulates muscle contractions (including the heart), and supports nerve function. Dairy products like milk, cheese, and yogurt are rich sources of easily absorbed calcium but are often excluded from vegan diets. Some plant-based sources like kale, spinach, sesame seeds, almonds, and tofu contain calcium, but in lower amounts and are less readily absorbed. Oxalates in vegetables like spinach and beets can hinder calcium absorption, as can phytates in whole grains, nuts, and seeds.

A long-term calcium deficiency can lead to reduced bone density, osteoporosis, and an increased risk of fractures, especially in premenopausal women. Vegetarians can supplement with calcium or consume plant-based milk fortified with this mineral.

Omega-3s (DHA and EPA)

Omega-3s are essential fatty acids crucial for brain structure, nervous system function, vision, and cardiovascular health. They help lower triglycerides and LDL cholesterol, reduce inflammation, and may lower the risk of depression and anxiety. DHA and EPA are the two most important active forms of omega-3s and are abundant in fatty fish.

While the body can convert a small amount of ALA (alpha-linolenic acid found in flaxseeds, chia seeds, and walnuts) into DHA and EPA, the conversion rate is low (5-10%). This is often insufficient to meet normal physiological needs, especially for pregnant and breastfeeding women. Vegetarians should increase their intake of omega-3-rich foods like chia seeds, pistachios, flaxseeds, and soybeans. They can also consult a doctor about omega-3 supplements derived from algae.

Zinc

Plant-based sources of zinc include legumes, whole grains, pumpkin seeds, and sunflower seeds. However, phytates in grains, nuts, sesame seeds, and soybeans can inhibit zinc absorption. Zinc deficiency can weaken the immune system, increase susceptibility to infections, slow wound healing, and impair taste and smell. It can also lead to hair loss, dry skin, and weak nails. If a vegetarian diet is low in zinc, supplementation should be considered after consulting a doctor.

Vitamin D

Vitamin D3, found primarily in salmon, liver, eggs, milk, and butter, enhances calcium and phosphorus absorption, supports immune function, and contributes to muscle and nervous system function and mood regulation. Vegetarians should get 10-15 minutes of daily sun exposure (in the morning or afternoon, without excessive covering or sunscreen application) and consume vitamin D3-rich foods like mushrooms and fortified soy milk.

Protein

Protein builds and maintains muscles, tissues, organs, and the immune system. It also supports memory, focus, and nerve function. Vegetarians should choose and combine protein-rich foods like tofu, tempeh, edamame, lentils, black beans, nuts, nut butters (peanut butter, almond butter), and vegetables.

According to Hieu, including eggs and dairy can provide additional animal protein. Steaming, boiling, and mixing foods, rather than frying or grilling, can help reduce the risk of obesity and related diseases. Regular health check-ups are important. Doctors can use high-performance liquid chromatography (UPLC) to determine any nutrient deficiencies or excesses. This allows them to provide personalized dietary advice and recommend appropriate supplements.

Trinh Mai