Vegetarianism and bone health. How to balance your diet properly?

Vegetarian diets are becoming more and more popular. Even declared carnivores, traditionalists, and athletes choose it. But is a vegetarian diet the right way to eat? Can it affect fractures and bone mineralization?

Table of content:

1. Vegetarianism
2. Classification of vegetarianism
3. Vegetarianism and deficiencies
4. Determinants of healthy bones
   • protein
   • calcium
   • vitamin B12
   • vitamin D
5. Risks for bones
   • osteoporosis
   • osteomalacia
   • rickets
6. Bone health and type of vegetarianism
7. Vegetarian diet and health
8. Vegetarian products for bone health
9. Summary

What is vegetarianism?

Vegetarian diet is also sometimes called a plant-based diet. The premise of this diet is to eliminate animal products from meals, i.e., meat (including poultry), seafood and fish. Food containing animal products (jelly – beef gelatin) is also not eaten. Vegetarian diets can be appropriate at any stage of a person’s life. They are: infancy, childhood, adolescence, adulthood, pregnancy, lactation. This diet can also be healthy for athletes (Craig, Mangels & American Dietetic Association, 2009).

The American Dietetic Association (ADA) considers a balanced vegetarian diet to be one of the healthiest ways to eat. It was recognized that it can cover the need for all nutrients. Studies have indicated that a plant-based diet can improve the intake of fiber, folic acid, magnesium, vitamins B1, B6, C, E. The intake of these nutrients is significantly lower in meat eaters (Neufingerl & Eilander, 2022). This is due to the higher consumption of fruits, vegetables, whole grains and nuts by vegetarians. As a result, vegetarian diets often contain less saturated fat and cholesterol. In addition, potassium, carotenoids, and flavonoids. These are definitely the advantages of a varied and balanced vegetarian diet.

It has also been shown that people on a vegetarian diet have a 50% lower risk of developing diverticular disease. The protective effect of fiber contributes to this. Meat consumption has been found to increase the risk of developing this disease (ADA, 2015).

Types of vegetarian diets

The ADA recognizes vegetarian (including vegan) diets as a healthy way to eat. Properly balanced, they can be nutritional and provide benefits in the prevention and treatment of certain diseases (Craig, Mangels & American Dietetic Association, 2009). The vegetarian diet has undergone more or less restrictive modifications.

Lacto-ovo vegetarianism, lacto-vegetarianism, ovo-vegetarianism, pesca-vegetarianism and veganism are some types of vegetarianism. However, each of these diets is associated with an individual assessment of nutritional status and diet.

Is a Vegetarian Diet Dangerous?

Nutrient deficiencies may be the consequence of an unbalanced diet. The plant-based diet is no different. However, some ingredients require more attention. This is often due to the elimination of products from the diet that are the main source of these ingredients. Deficiency may also result from poorer absorption, i.e., bioavailability.

According to studies, vegetarians in the body may have lower levels of iron, zinc, iodine, vitamin B12, calcium, vitamin D and protein.

Iron

Iron has two forms: heme and non-heme. Animal products contain both forms, including about 40% of heme iron. Iron is found in non-heme form in plant foods. Therefore, better absorption of iron belongs to meat products. It is 2-3 times bigger (Kowalska, 2019). A high level of iron in a vegetable product does not mean that the demand is covered in this amount. The body uses it at a low percentage. Studies have indicated that the lower iron levels in vegetarians and vegans were due to significantly lower iron bioavailability (Neufingerl and Eilander, 2022). For this reason, vegetarians are recommended 1.8 times higher doses of iron.

The state of health and proper composition of meals also have an impact on the absorption. Non-heme iron is more sensitive to the effects of other ingredients. Oxalates, phytates, polyphenols, fiber, and calcium. They contribute to the lower absorption of iron from the gastrointestinal tract. Iron absorption can be enhanced by choosing the right preparation techniques. Soaking beans, seeds, and cereals or acidifying bread, for example, can reduce phytate levels. Vitamin C, organic acids, lactic acid (pickled products) support the absorption of iron. In addition, fruits and vegetables containing vitamin C and other organic ingredients.

Studies have proved that vegetarians had lower levels of iron in their bodies than vegans. This may be due to the consumption of dairy as a source of protein by vegetarians. This group should consume more iron-rich foods, including vegetables and fruits containing vitamin C (Neufingerl & Eilander, 2022). Interestingly, studies conducted in different countries (Italy, Great Britain, Austria) have shown that people on a traditional diet obtained a higher amount of iron from cereal products (flakes, bread, groats) than from meat (Kowalska, 2019).

It is proven that adaptation to low iron supply is possible. In the case of increased bioavailability, but also reduced iron loss. The incidence of iron deficiency anemia is similar in vegetarians and non-vegetarians. Vegetarian plasma ferritin levels are usually normal (ADA, 2015).

Vitamin B12

Studies have shown that vitamin B12 levels are significantly lower in vegetarians and vegans. Meat eaters have a 0 to 16% incidence of this vitamin deficiency. Vegetarians 0 to 75% and vegans 4% to 73%. It is estimated that 32% of vegetarians and 44% of vegans are deficient in vitamin B12. This may be because the main source of this vitamin are animal products (meat, fish, eggs, dairy products) (Wojda, 2020). It is recognized that there is no plant product that, without enrichment, would have a sufficient active amount of vitamin B12.

Interestingly, a large amount of folic acid in a plant-based diet may hide the symptoms of this vitamin deficiency. If this is the case, it may only be detected when neurological signs and symptoms appear (ADA, 2015).

Vitamin B12 can be obtained from regular consumption of fortified foods or supplements. Which is the main recommendation for vegans. Lacto-vegetarians or lacto-ovo vegetarians can also obtain it from dairy products and eggs. However, this may not be enough (Neufingerl and Eilander, 2022).

Zinc

Reduced zinc absorption may be due to high phytate and fiber content in the diet. On a plant-based diet, it is recommended to increase zinc intake by 50%. Due to the low bioavailability, the level of zinc in the body of vegetarians is lower than the average requirement. However, health consequences in vegetarians have not been demonstrated (Neufingerl & Eilander, 2022).

Vegetarians eating mainly products rich in phytic acid have a higher need for zinc. Studies show varying levels of zinc in the body of vegetarians. Some show results close to the recommendations, others too low. Western vegetarians have not been shown to be deficient in zinc (ADA, 2015).

The source of zinc can be soy products, cereals, nuts, and legumes. As with iron, certain food preparation techniques can increase absorption. In addition, organic acids (citric acid) can also positively affect the absorption of zinc (ADA, 2015).

Iodine

Some studies have proved that vegetarians and vegans consume less iodine than meat eaters. This may be due to the higher content of iodine in animal products than in plant products. The richest sources of iodine are fish and dairy products. The number of foods containing iodine is limited. Therefore, WHO recommends the consumption of iodized salt, also in food, i.e., bread, bouillon cubes, spices. Seaweed is also a source of iodine (Neufingerl and Eilander, 2022).

Vitamin D

In the diet of vegetarians and vegans, vitamin D is considered to be one of the most common deficiency ingredients. It is found in a few products, i.e., fatty fish, eggs, meat, algae. The highest intake of vitamin D was noted in people who regularly eat fish. Vitamin D should be consumed with fat-containing foods. This is due to its properties, i.e., solubility in fats. Thanks to this, the absorption of vitamin D in the body increases (Bieńko, 2018). However, the amount of this vitamin depends mainly on sun exposure, skin pigmentation and supplementation. In the autumn and winter, vitamin D supplementation is recommended, not only for people on a plant-based diet. The dose should be adjusted according to age and body weight. Obese people should consume a higher dose (Wolańska-Buzalska, 2018). Healthy adults are recommended 20-50 µg/day, i.e., 800-2000 IU. However, the dose should be consulted to a doctor along with the control of vitamin D levels in the blood (Wojda, 2020). During the period of the greatest insolation in Poland, supplementation is not necessary. Because of sunlight, it is synthesized in the skin. Children are recommended 30 minutes of sun exposure before 11 a.m. and after 2 p.m. (Bieńko, 2018).

Determinants of healthy bones

The most intensive development of the skeletal system occurs in the first three years of life. Their density, thickness, length, and calcium level in the bone tissue increase (Bieńko, 2018). After the age of 30, bone mass decreases slowly. During a woman’s lifetime, it can decrease by half (45-50%). Bone mineral density is affected by a balanced diet and a healthy lifestyle. The goal is to maintain the highest possible level of peak bone mass until the age of 30 (Wolańska-Buzalska, 2018).

Deficiency, as well as excess body weight, can disturb the level of bone mineral density. Excess kilograms contribute to various diseases that can lead to osteoporosis (Wolańska-Buzalska, 2018).

Regular physical activity (30-45 minutes a day) can have a significant impact on building and maintaining bone mass. It’s the opposite with drugs. Alcohol consumed daily (1-2 servings) impacts the deficiency of calcium, phosphorus, and vitamin D. It inhibits the building of bone and cartilage tissue. Nicotine, on the other hand, increases the level of cortisol in the blood and can lead to bone loss. The formation and resorption of bones is influenced by the intake of calcium, protein, vitamins D and B12 and magnesium.

Calcium

Calcium is essential for bone health. 99% of this component is found in bone tissue. Providing it in the right amount affects the construction and maintenance of bone mass (Wolańska-Buzalska, 2018). Vegetarians and vegans have been shown to provide less calcium than meat eaters. However, the level of calcium in people on a traditional diet is also below average (Neufingerl and Eilander, 2022). Calcium levels in the body of lacto-ovo vegetarians were similar to or higher than those of meat eaters. Vegans had lower levels with a tendency to fall below recommendations (Neufingerl & Eilander, 2022). Fiber, phytates and oxalates from plant foods may have a negative impact on calcium absorption. An example is spinach or chard. They contain oxalates. Adequate protein and vitamin D may contribute to increased absorption (ADA, 2015).

Protein

Protein is a nutrient that is involved in the construction of all tissues, enzymes, and hormones. In addition, it is responsible for transporting other ingredients, i.e., vitamins A and B12 and iron. Protein also increases the rate of calcium absorption (Knurick et al., 2015). Studies show a significant effect of protein on bone mass gain and reduce the risk of fractures. Especially in the elderly (Knurick et al., 2015). Vegetarians sometimes consume less protein than people on a meat diet. Despite this, it is not difficult to provide this ingredient on a plant-based diet. Legumes are the main source of protein. They consist of 21-25% protein. In addition, they contain lysine, which is the most important amino acid in the plant diet. Cereal products contain 7-14% protein. Green vegetables contain more protein. An example is peas, which contain 6% protein, and Brussels sprouts 5% (Kibil, 2020). Cereals are usually low in lysine. In this case, you should choose products that contain it, e.g., beans. The diets of lacto-ovo vegetarians and vegans, on average, contain or even exceed the required level of protein. Athletes can also meet their protein needs on plant-based diets (ADA, 2015). There have been several intervention studies related to soy protein supplementation. The study was performed on elderly men following a vegetarian diet. The men consumed soy protein during 12 weeks of resistance training. The results showed the benefit of soy protein supplementation in improving muscle mass and strength (Knurick et al., 2015).

Vitamin B12

The main source of vitamin B12 are animal products and of animal origin, i.e., milk, eggs. Proper intake of vitamin B12 may be difficult for people following a vegetarian diet. Vegans should consume products fortified with vitamin B12 (soy drinks, rice drinks). Unfortunately, it is a vitamin that only in fortified foods contains a reasonable amount for vegans and vegetarians. There is no plant product that has an active form of vitamin B12. It is synthesized only by microorganisms, which is why it is not present in food of plant origin (Pawlak, 2013).

Products fortified with vitamin B12 are recommended, as well as supplementation. However, you should determine your vitamin B12 dosage with your doctor (Klemm, 2021).

Vegetarian diets are generally high in folic acid, which may mask the hematologic symptoms of vitamin B12 deficiency. In this way, a deficiency of this vitamin can go undetected until neurological signs and symptoms appear. The level of vitamin B12 is best determined by measuring the level of homocysteine, methylmalonic acid or holotranscobalamin in the blood serum (ADA, 2015).

Vitamin D

The intake of this vitamin is much lower than the average demand of the population, not only in people on a plant-based diet. Insufficient vitamin D intake occurs in the general population and can affect all dietary regimens. The deficiency of this vitamin in meat eaters is 0-6%, vegetarians 0-33%, and vegans 3-67%. The average prevalence of vitamin D deficiency in meat eaters was shown to be 15% and 25% in vegetarians (Neufingerl & Eilander, 2022).

Vitamin D impacts the activity of cells (osteoblasts) that influence the bones. In addition, it increases the absorption of calcium, which increases its level in the body (Monika Zaleska-Szczygieł, bdw). In addition to calcium, vitamin D has a beneficial effect on the absorption of phosphorus. These two ingredients are the building blocks of teeth and bones (Bieńko, 2018.)

Unfortunately, food products are not a sufficient source of vitamin D. The main source of vitamin D is UV rays, possible supplementation. Deficiency of this vitamin often results from insufficient exposure to the sun, excessive skin pigmentation, air pollution, too low vitamin D intake or eating habits (Hashemipour et al., 2004). It is believed that people up to the age of 18 should take an additional dose of this vitamin from fortified products. However, when children turn two years old, they should consume more milk and milk products (Bieńko, 2018). In the autumn and winter, vitamin D should be supplemented. The dose of vitamin D should be supervised by a doctor (Wojda, 2020).

Danger of bone weakness

Osteoporosis

Osteoporosis is characterized by reduced bone mass and density. The consequence is their fragility at low physical loads (Jakob, 2007). Fracture risk can be determined by bone mineral density testing. Programs and exercises are used to prevent falls. In addition, drugs are prescribed to reduce the risk of fractures. The disease was more common in women. The most important is too low level of vitamin D in the body (Monika Zaleska-Szczygieł, bdw). The cause is noticed in the incorrect work of the hormonal glands (thyroid, adrenal glands) and the absorption of calcium in the intestines, and in kidney diseases.

Symptoms may include:

• long bone pain
• spine pain
• thoracic kyphosis/senile hump
• bone fracture with minor injuries
• vertebral compression fracture

Prevention consists in supplementing calcium, vitamin D and protein deficiencies. Physical activity is also important to strengthen the bones and muscles to stabilize the posture.

Osteomalacia

Osteomalacia is a bone disease associated with a deficiency of vitamin D and calcium in the body. The consequence is the weakening and reduction of bone hardness, the so-called softening of the bones.

Insufficient sun exposure, malabsorption, abnormal phosphate metabolism can lead to osteomalacia. The cause may be other diseases, such as cancer, kidney failure or liver disease (vitamin D is not converted into the active form) (Jakob, 2007).

Symptoms of osteomalacia may include:

• bone fractures without trauma
• weak muscles
• frequent falls in the elderly
• pain around the hip bones

In addition, low calcium levels contribute to:

• numbness around the mouth, arms, and legs
• hand or foot cramps
• Recovery is possible with a deficiency. Improvement can take several weeks to 6 months (Penn Medicine, 2022).

A diet rich in calcium and vitamin D (supplementation, preferably in the form of a drug or exposure to sunlight) is recommended to prevent osteomalacia resulting from vitamin D deficiency (Penn Medicine, 2022).

Rickets

Rickets is a disease associated with abnormal bone mineralization. The cause is a deficiency of vitamin D3, calcium or phosphate. The result is bone deformity. They become delicate, softened and prone to breakage. Most cases occur between the third month and the second year of life. Rickets is defined as a disease of childhood. Providing the body with the right dose of vitamin D prevents this disease (Bieńko, 2018).

Symptoms of rickets:

• flattened and soft back part of the head
• enlarged fontanel and delayed overgrowth
• chest deformity (bell-shaped chest, crow’s chest)
• thickened ribs at the junction of cartilage with bone (rachitic rosary)
• curvature of the spine (rachitic hump)
• malformed pelvis
• thickening of the epiphyses of the hands (rachitic bracelets)
• curvature of the lower limbs (valgus knees)
• flat feet
• In addition, delayed growth and tooth eruption, caries, tetany and reduced resistance to infections (Bieńko, 2018).

Rickets can be the result of improper nutrition. Inadequate ratio of calcium to phosphorus in nutrition or insufficient insolation. Premature babies have an insufficient amount of vitamin D accumulated before birth. To cure rickets in a child, vitamin D is introduced in fixed doses (Bieńko, 2018).

Bone health and type of vegetarianism

The risk of bone fractures in lacto-ovo vegetarians and non-vegetarians is similar. Vegans had a 30% higher risk. Which is probably related to their lower calcium intake (ADA, 2015).

The source of calcium in the traditional diet is cow’s milk. It has a favorable ratio of calcium to phosphorus in the body. Lacto-vegetarians and lacto-ovo vegetarians have similar calcium content in their diets. It is estimated that the supply of calcium from these diets is higher than in a traditional diet (Wojda, 2020). Vegans give up dairy and eggs, and this reduces the number of products that provide calcium. This contributes to the risk of deficiency of this nutrient (Wojda, 2020).

Vegetarians and vegans have been shown to have higher PTH levels and greater bone resorption compared to meat eaters (Neufingerl & Eilander, 2022).

Vegetarians and vegans should pay attention to the proportion of calcium and protein in their diet. Both have been found to be more beneficial to bone health than dietary calcium levels alone. It is noted that lacto-ovo vegetarians have this proportion at a high level. By contrast, vegans are similar or lower than meat eaters.

Plant-based diets have been shown not to be harmful to bones when properly balanced. Studies have been conducted on the effect of whole foods on the risk of fractures. These studies lasted 25 years. The foods eaten were high in protein (including beans, nuts, vegetarian meat analogs, and cheese). The result was a lower risk of distal forearm fractures in vegetarian women. When all subjects were analyzed together, vegetarian women were no more likely to suffer a wrist fracture than meat-eaters. Mineral density was found to be no different between lacto-ovo-vegetarians, vegans and omnivores. This confirmed the harmlessness of a plant-based diet for bones in young adults.

It has been noticed that there are nutrients in the vegetarian diet that are missing in the traditional diet. It has been recognized that a well-balanced vegetarian diet can provide bone-strengthening properties. Therefore, a diet for bone health in meat eaters should include more fruits and vegetables, and vegetarians should include more vegetable protein (Knurick et al., 2015). It has been noted that a balanced plant-based diet is possible in athletes. However, it is recommended to control the amount of protein, iron, calcium, and omega 3 in the body (Parol, 2018).

Vegetarian diet and bone health

Too little protein and calcium intake contributes to hip fractures, spine fractures and bone loss in the elderly. Vegetarians have been shown to have the same fracture risk as meat eaters. The increased risk of fractures in vegans was due to calcium deficiency. Vegans who got the right amount had a similar risk of fractures as vegetarians and meat eaters. Increased consumption of fruit and vegetables has a beneficial effect on calcium metabolism and markers of bone metabolism. The high content of magnesium in the diet of vegetarians affects the inhibition of bone resorption. Potassium in a plant-based diet affects markers of bone health, helping to reduce the risk of osteoporosis. Interestingly, a high intake of animal protein with a low amount of plant protein has been shown to result in a high rate of bone loss and an increased risk of hip fracture. Excessive intake of protein, especially animal protein, promotes increased excretion of calcium in the urine (hypercalciuria). It has been noted that soy protein (isoflavones) may reduce spinal bone loss. Soy isoflavones have a significant effect on the bone mineral density of the spine. In addition, they can stimulate the growth of bone mass and inhibit bone resorption (ADA, 2015).

Lacto-ovo vegetarians have similar spongy and cortical bone mineralization to meat eaters. For vegans, the density level may be lower. Hip fracture risk and predicted bone mineral density are assessed using markers of body vitamin K levels (ADA, 2015).

It was noted that deficiencies occur in every group. On a vegetarian diet compared to a meat diet and vice versa. Studies have indicated that vegan women had very low calcium and protein intakes and were deficient in vitamin D (ADA, 2015). Meat-containing diets are also associated with vitamin D and calcium deficiencies (Neufingerl & Eilander, 2021).

There is currently conflicting information regarding the impact of a vegetarian diet on bone health. Therefore, it is always justified to follow the recommendations of a healthy diet. It aims to provide the body with an adequate supply of micro- and macronutrients. A diet that provides adequate amounts of calcium, protein, vitamin D and B12 should not negatively affect fracture risk (Falchetti et al., 2022).

There is currently no evidence that a properly balanced, plant-based diet is detrimental to bone health. It is suggested that a long-term vegetarian diet may reduce the symptoms of osteoporosis (Hsu, 2020).

Vegetarian products for bone health

Nutritional deficiencies that are associated with poor bone health are preventable. A properly planned vegetarian diet can promote healthy bones. Increase your intake of vegetable protein, legumes, fruits, vegetables, whole grains, nuts and various soy products. This will positively affect the level of nutrients needed to maintain healthy bones (Chuang, Lin & Wang, 2020).

Calcium

Dairy products are considered to be a rich source of calcium. People who do not consume these products should use plants containing this ingredient (Klemm, 2021).

• fortified vegetable soy or almond drinks
• enriched ready-to-eat cereals
• calcium-enriched juice
• tofu with added calcium
• green leafy vegetables low in oxalate (broccoli, kale, turnips, and kale)
• fortified fruit juices
• legumes
• beans, soybeans, chickpeas, and black beans
• nuts
• almonds and almond butter
• sesame seeds, poppy seeds
• mineral waters
• amaranth
• parsley
• kefir, buttermilk, yogurt, cheese

Vitamin B12

Adequate vitamin B12 intake can be a concern for many vegetarians, especially vegans. People who follow vegetarian diet should choose products fortified with vitamin B12. It is also recommended to consult a doctor for vitamin B12 supplementation (Wojda, 2020).

• fortified foods, including fortified nutritional yeast, soy and rice drinks,
• meat substitutes
• ready-to-eat cereals
• Dairy
• Eggs

Protein

Protein is found in both plant and animal foods. The body produces its own complete protein if a variety of foods and enough calories are eaten throughout the day.

• Legumes: beans, peas and lentils
• Whole grain products
• soy products
• Nuts and peanut butters
• Dairy
• Eggs

Vitamin D

Few foods are naturally rich in vitamin D. People who have chosen not to consume dairy products or are unable to expose themselves to the sun should discuss vitamin D intake with their doctor.

• Soy drinks enriched with vitamin D
• Orange juice
• ready cereals
• cow milk
• Eggs
• Mushrooms exposed to sunlight

It is recommended to maintain a healthy lifestyle. Increase physical activity, reduce caffeine and alcohol intake, and quit smoking (Chuang, Lin & Wang, 2020).

Summary and Conclusions

Vegetarian diets, including vegan ones, have been recognized as a healthy way of eating. They can be nutritious and provide benefits in the prevention and treatment of certain diseases. As long as it is properly balanced. Nutritional deficiencies can occur in any unbalanced diet. Plant-based diets also increase the risk of deficiency of vitamin B12, vitamin D, calcium, iron, zinc, and iodine. However, vegetarianism and veganism show a higher intake of other nutrients, i.e., magnesium, folic acid, vitamin K. These vitamins are deficient in omnivores.

Vegetarianism is classified according to certain modifications. Which may slightly affect the difficulty of choosing food products in the diet. In the case of lacto-vegetarians and lacto-ovo-vegetarians, the level of calcium is at a similar or higher level than in people using a traditional diet. Vegans who do not consume dairy should take care of the appropriate balance of ingredients affecting bone tissue.

In conclusion, a properly balanced vegetarian diet does not lead to health problems. Adequate supply of nutrients and adherence to the principles of maintaining bone health do not increase the risk of disease. The supply of ingredients may be a bit difficult for vegans. Any unbalanced diet can lead to various diseases, including bones.

Frequently Asked Questions

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