Lacto-ovo-vegetarianism is a subclass of vegetarianism.

While vegetarians eat a mostly plant-based diet, avoiding meat and animal-origin foods, lacto-ovo-vegetarians allow the consumption of dairy and eggs.

Dairy products such as cow’s milk, cheese, and yoghurt offer an essential source of protein, fat and micronutrients such as vitamin B12, calcium, and zinc.

Eggs are a great source of protein, vitamins and minerals (Griffin, 2016).

According to the Encyclopaedia of Human Nutrition “Eggs are one of the few natural sources of vitamin D and B12” (Caballerro, 2005).

Strict vegetarian diets that contain no animal-origin foods, are generally lacking in vitamin B12, calcium, iron, vitamin D, and zinc (Rizzo et al., 2013).

Individuals may choose a lacto-ovo-vegetarian diet for the reported health benefits, for environmental reasons, or because they just enjoy the taste and flavour of dairy and eggs.

A lacto-ovo-vegetarian diet may appeal to those you are looking to reduce the amount of meat and animal products in their diet, while still being able to consume dairy and eggs.

In this article we explain (in plain English!) the conclusions of scientific studies that have looked at lacto-ovo-vegetarianism. 

Vegetarian diets consist predominantly of plant-based foods abundant in whole grains, legumes, nuts, seeds, fruits, and vegetables, while avoiding red meat, processed meat products, refined foods, and sweets.

There are several variations of a vegetarian diet:

  • Lacto-vegetarians allow the consumption of low-fat dairy products
  • Ovo-vegetarians allow the consumption of eggs
  • Pescatarians allow the consumption of fish
  • Pollotarians allow lean white meat such as chicken to be consumed.

Drawbacks of Lacto-Ovo-Vegetarianism

In this section, we will discuss the drawbacks of a lacto-ovo-vegetarian diet.

It is advised to consult with your primary care physician or a registered dietitian before following a new diet.

High in Saturated Fat

Dairy products and eggs, both contain high levels of dietary saturated fatty acids (SFA) and cholesterol (Caballerro, 2005).

Dietary guidelines suggest limiting your intake of saturated fatty acids and cholesterol, both of which have been linked to cardiovascular disease.

However, according to a recent study published in The American Journal of Clinical Nutrition, SFAs from dairy, will not lead to an increased rate of heart disease, and in fact low-fat dairy is linked to a decrease in diabetes risk “The totality of evidence does not support that dairy SFAs increase the risk of coronary artery disease or stroke or CVD mortality. In contrast, lean dairy is clearly associated with decreased risk of type 2 diabetes” (Astrup, 2014).

The food matrix in which the SFAs are consumed also matters.

Dairy products when consumed in a balanced healthful plant-based diet, may not lead to an increased risk of diabetes and heart disease.

Eggs: Good or bad?

Eggs contain a high amount of dietary cholesterol (Rosenson & Song, 2019).  

Cholesterol (a type of waxy fat) is associated with heart disease, and should be limited in the diet.

Eggs have been a source of contention for decades: are they good or bad for our health?

According to Caballero (2005), “studies have shown that saturated fat, not dietary cholesterol, is the major dietary determinant of plasma cholesterol levels, and that neither dietary cholesterol nor egg consumption are significantly related to the incidence of cardiovascular disease”.

They also went on to say that “those countries with the highest egg consumption actually have the lowest rates of mortality from cardiovascular disease”.

A further study published in the Proceedings of the Nutrition Society, investigating whether eggs were good or bad for your health, concluded that eggs most likely are not bad for you “the answer to the question as to whether eggs are ‘bad’, is probably ‘no’” (Griffin, 2016).

Although containing a high amount of dietary cholesterol, eggs contain a relatively low amount of saturated fat, and when eaten in moderation with a plant-based diet may positively impact your health.

Food Allergens and Food Intolerances

A lacto-ovo-vegetarian diet may not be applicable to some individuals with food allergens or intolerances.

Milk and eggs are some of the most common food products causing allergic reactions (FDA, 2022).

Some individuals may have an intolerance to lactose, where by their body does not produce the enzyme needed to break down lactose in the gut, leading to gastrointestinal distress (Bahna, 2002).

While others may suffer from a milk allergy which is an immune response to cow’s milk protein, and causes skin reactions, hay fever-like symptoms, and gastrointestinal issues (Host, 2002).

Young children are most prone to developing an egg allergy, however in most cases it is overcome by age 5. Infants younger than 6 months should not be fed eggs (Caballerro, 2005).

Individuals with known dairy or egg allergies or intolerances should not consume a lacto-ovo-vegetarian diet.

Benefits of Lacto-Ovo-Vegetarianism

Despite the drawbacks of a lacto-ovo-vegetarian diet covered in the previous section, numerous studies have reported the many health benefits of a lacto-ovo vegetarian diet.

In the sections that follow we highlight studies that have linked lacto-ovo-vegetarianism with health benefits such as:

  • Reduced risk of hypertension
  • Weight loss
  • Reduced risk of diabetes
  • Cardiovascular health benefits
  • Reduced bone mineral loss
  • Reduced cancer incidence
  • Athletic performance

Reduced Risk of Hypertension

A lacto-ovo-vegetarian diet may reduce your chances of developing hypertension (high blood pressure).

A 2020 review published in the Journal of Hypertension, investigated the influence of various plant-based dietary patterns (Lacto-ovo, Mediterranean, and vegan) on blood pressure.

The authors analysed 41 clinical trials, consisting of 8416 participants, with an average age of 49.2 years.

They reported that all plant-based dietary styles evaluated in the present study were linked to a reduction in blood pressure, with lacto-ovo-vegetarianism exhibiting the greatest improvement “Plant-based diets were associated with lower systolic blood pressure, Mediterranean −0.95 mmHg, Vegan −1.30 mmHg, and Lacto-ovo vegetarian −5.47 mmHg; The certainty of the results is high for the lacto-ovo vegetarian and Dietary Approach to Stop Hypertension diets” (Gibbs et al., 2020).

Weight Loss

Lacto-ovo-vegetarianism may aid in weight loss and weight control.

According to a 2009 study published in the journal, Diabetes Care, lacto-ovo-vegetarians have lower body mass indices (BMI) than non-vegetarians (Tonstad et al., 2009).

Scientists from the present study examined data from the Adventist Health Study-2 (2002-2006), which consisted of 22 434 men and 38 469 women.

They reported that on average, vegetarians had lower BMI’s than non-vegetarians, with vegans and lacto-ovo-vegetarians displaying the lowest BMI of the study, at 23.6 kg/m2 and 25.7 kg/m2 respectively, while non-vegetarians had a mean BMI of 28.8 kg/m2.

The authors also reported that vegetarian participants had lower chances of developing type 2 diabetes “Vegans, lacto-ovo vegetarians, pesco-vegetarians, and semi-vegetarians had a lower risk of type 2 diabetes than non-vegetarians” (Tonstad et al., 2009).

Reduced Risk of Diabetes

A lacto-ovo-vegetarian diet may improve your insulin sensitivity and reduce your chances of diabetes.

Insulin, is the hormone responsible for maintaining blood-glucose levels. Insulin enables your body to use glucose effectively and lowers blood-glucose levels. The more sensitive your body is to insulin, the lower the risk of diabetes.

A study published in the European Journal of Clinical Nutrition, examined the insulin sensitivity of lacto-ovo-vegetarians in comparison to omnivores, in a Chinese population.

Compared to the omnivorous participants, the lacto-ovo-vegetarian participants displayed a greater insulin sensitivity “The vegetarians were more insulin sensitive than the omnivore counterparts” (Kuo et al., 2004).

They also went on to state that insulin sensitivity was higher in those who had adhered to a lacto-ovo-vegetarian diet for longer “The degree of insulin sensitivity appeared to be correlated with years on a vegetarian diet” (Kuo et al., 2004).

A 2017 meta-analysis published in the journal, Nutrients, examined the relationship between plant-based diets and the incidence of diabetes.

Data from 14 studies, published between 1980 and 2016 were analysed.

Based on results from the studies evaluated, the authors of the present study reported that those following a lacto-ovo-vegetarian diet were less likely to develop diabetes than those following an omnivorous diet “In the subgroup analysis by vegetarian type, vegan, lacto- and lacto-ovo-vegetarians had a lower risk of diabetes when compared to the omnivore group” (Lee & Park, 2017).

Cardiovascular Health Benefits

A lacto-ovo-vegetarian diet may provide protective benefits to your cardiovascular health.

A 2020 study published in the journal, Nutrients, examined the influence of a lacto-ovo-vegetarian diet on coronary artery disease (CAD).

Participants were instructed to follow a 4-week lacto-ovo-vegetarian diet (VD), followed by a 4-week break, and then a 4-week meat diet (MD). Plasma lipids of participants was measured following each diet.

The vegetarian diet was associated with an increase in healthy polyunsaturated fats, while lowering the “bad” saturated fats “VD increased triacylglycerols with long-chain polyunsaturated fatty acyls while decreased triacylglycerols with saturated fatty acyls, phosphatidylcholines, and sphingomyelins than MD” (Djekic et al., 2020).

The authors went on to say that adherence to a lacto-ovo-vegetarian diet positively changed the lipid profile of the individuals, and reduced levels of “bad” fats linked to heart disease “The VD favourably changed levels of several lipotoxic lipids that have previously been associated with increased risk of coronary events in CAD patients” (Djekic et al., 2020).

Ischemic heart disease - also known as coronary heart disease - is characterised by narrowing of the heart’s arteries, reducing the amount of blood and oxygen flow to the heart, which could result in a heart attack.

According to a 2012 study published in the journal, Annals of Nutrition and Metabolism, a vegetarian diet (lacto-ovo and vegan) is protective against ischemic heart disease (IHD) mortality, and can lower your chances of mortality by 29% (Huang et al., 2012).

Reduced Cancer Incidence

A lacto-ovo-vegetarian diet may provide protection against cancer.

A 2012 systematic review, performed by scientists from the Department of Food Science and Nutrition, Zhejiang University, and the APCNS Centre of Nutrition and Food Safety, Hangzhou, China investigated the association between a vegetarian diet (vegan and lacto-ovo-vegetarian) and total cancer incidence.

Data from 7 scientific studies, including over 120 000 participants from the UK, Germany, USA, the Netherlands, and Japan, was analysed.

The results from the study indicate that a vegetarian diet lead to an 18% reduction of total cancer occurrence among the participants “We found that the overall cancer incidence in vegetarians was 18% lower than in non-vegetarians” (Huang et al., 2012).

Athletic Performance

A lacto-ovo-vegetarian diet may provide the same exercise capacity as an omnivorous diet.

A 2019 cross-sectional study published in the Journal of the International Society of Sports Nutrition, investigated the effect of plant-based diets (vegan and lacto-ovo-vegetarian) in comparison to omnivorous diets on exercise capacity.

Exercise capacity was determined using a bicycle ergometer. Participants were instructed to exercise on the bicycle until they felt they were too tired to continue.

The findings of the present study indicate that both vegan and lacto-ovo-vegetarian diets were comparable to an omnivorous diet in terms of exercise ability (training frequency, running time, and distance) “the results suggest that there are no differences in exercise capacity between vegan, lacto-ovo-vegetarians and omnivorous recreational runners” (Nebl et al., 2019).

The authors concluded that based on their findings, a lacto-ovo-vegetarian diet is an appropriate diet for recreational athletes “a lacto-ovo-vegetarian and also vegan diet might be suitable alternatives for recreational athletes” (Nebl et al., 2019).

Reduced Bone Mineral Loss in Aging Adults

A lacto-ovo-vegetarian diet may be protective against bone mineral loss as you age.

A study published in the Journal of the American Dietetic Association, examined the bone density of omnivorous and lacto-ovo-vegetarian women, aged fifty to eighty-nine years.

They reported that the lacto-ovo-vegetarian participant’s bone mineral mass was reduced by 18%, over the follow-up period, while the omnivorous participant’s was reduced by 35% “Lacto-ovo-vegetarian women fifty to eighty-nine years of age lost 18 per cent bone mineral mass while omnivorous women lost 35 per cent” (Marsh et al., 1980).

The authors went on to state that based on the results of the current study, a lacto-ovo-vegetarian diet could prevent the loss of bone mineral mass of women in their later years “lacto-ovo-vegetarian diet may be beneficial in extended protective health care in terms of defence against, or control of, bone mineral loss in the later years of a woman's life” (Marsh et al., 1980).

Improved Non-Alcoholic Fatty Liver Disease

A lacto-ovo-vegetarian diet may improve symptoms of non-alcoholic fatty liver disease (NAFLD).

A 2020 study published in the journal, Archives of Physiology and Biochemistry, evaluated the effectiveness of a lacto-ovo-vegetarian diet (LOV-D) on obese adults with non-alcoholic fatty liver disease (NAFLD).

In this clinical trial, 75 overweight or obese adults with NAFLD were instructed to follow a lacto-ovo-vegetarian diet or a standard weight-loss diet for 3 months.

The findings of this study highlight that a lacto-ovo-vegetarian diet in comparison to a standard weight-loss diet led to improvements in liver enzymes, reduced body weight, BMI, cholesterol, and blood pressure “This study suggests that adherence to LOV-D for 3 months has beneficial effects on NAFLD improvement” (Garousi et al., 2020).

Wrapping Up

Evidence suggests that a lacto-ovo-vegetarian diet is capable of providing you with countless health benefits and can lower your chances of hypertension, diabetes, cardiovascular disease, and even cancer.


Although containing dairy and eggs - food items that are high in saturated fat and cholesterol - a well-planned lacto-ovo-vegetarian diet, abundant in healthful plant-based foods such as whole grains, legumes, nuts and seeds, fruits and vegetables and moderate amounts of dairy and egg products is capable of positively influencing your health.


A lacto-ovo-vegetarian diet may appeal to those you are looking to reduce the amount of meat and animal products in their diet, while still be able to consume dairy and eggs.


Dairy and eggs offer added nutrition to a vegetarian diet, providing a great source of high quality protein, vitamin D and B12, zinc, and calcium, which would have otherwise been lacking in a strict vegetarian diet.


In order to reap the full health benefits of this diet, it is important to always try to consume food as close to its natural state as possible, while avoiding highly processed lacto-ovo-vegetarian meals that are generally high in additives such as salt, and preservatives which can have a negative impact on your health and negate the positive benefits gained.  


Finally, it is advised to consult with your doctor or dietitian to ensure that this diet is right for you.

References:

  • Astrup, A. (2014). A changing view on saturated fatty acids and dairy: from enemy to friend. The American Journal of Clinical Nutrition, 100(6), 1407-1408.
  • Bahna, S. L. (2002). Cow's milk allergy versus cow milk intolerance. Annals of Allergy, Asthma & Immunology, 89(6), 56-60.
  • Caballero, B. (2005). Encyclopedia of human nutrition. Elsevier.
  • Djekic, D., Shi, L., Calais, F., Carlsson, F., Landberg, R., Hyötyläinen, T., & Frøbert, O. (2020). Effects of a lacto-ovo-vegetarian diet on the plasma lipidome and its association with atherosclerotic burden in patients with coronary artery disease—a randomized, open-label, cross-over study. Nutrients, 12(11), 3586.
  • FDA (2022) 12/04/2022
  • Garousi, N., Tamizifar, B., Pourmasoumi, M., Feizi, A., Askari, G., Clark, C. C., & Entezari, M. H. (2021). Effects of lacto-ovo-vegetarian diet vs. standard-weight-loss diet on obese and overweight adults with non-alcoholic fatty liver disease: a randomised clinical trial. Archives of Physiology and Biochemistry, 1-9.
  • Gibbs, J., Gaskin, E., Ji, C., Miller, M. A., & Cappuccio, F. P. (2021). The effect of plant-based dietary patterns on blood pressure: a systematic review and meta-analysis of controlled intervention trials. Journal of hypertension, 39(1), 23-37.
  • Griffin, B. A. (2016). Eggs: good or bad?. Proceedings of the Nutrition Society, 75(3), 259-264.
  • Høst, A. (2002). Frequency of cow's milk allergy in childhood. Annals of Allergy, Asthma & Immunology, 89(6), 33-37.
  • Huang, T., Yang, B., Zheng, J., Li, G., Wahlqvist, M. L., & Li, D. (2012). Cardiovascular disease mortality and cancer incidence in vegetarians: a meta-analysis and systematic review. Annals of nutrition and metabolism, 60(4), 233-240.
  • Kuo, C. S., Lai, N. S., Ho, L. T., & Lin, C. L. (2004). Insulin sensitivity in Chinese ovo-lactovegetarians compared with omnivores. European journal of clinical nutrition, 58(2), 312-316.
  • Lee, Y., & Park, K. (2017). Adherence to a vegetarian diet and diabetes risk: a systematic review and meta-analysis of observational studies. Nutrients, 9(6), 603.
  • Marsh, A. G., Sanchez, T. V., Midkelsen, O., Keiser, J. O. A. N., & Mayor, G. I. L. B. E. R. T. (1980). Cortical bone density of adult lacto-ovo-vegetarian and omnivorous women. Journal of the American Dietetic Association, 76(2), 148-151.
  • Melina, V., Craig, W., & Levin, S. (2016). Position of the Academy of Nutrition and Dietetics: vegetarian diets. Journal of the Academy of Nutrition and Dietetics, 116(12), 1970-1980.
  • Nebl, J., Haufe, S., Eigendorf, J., Wasserfurth, P., Tegtbur, U., & Hahn, A. (2019). Exercise capacity of vegan, lacto-ovo-vegetarian and omnivorous recreational runners. Journal of the International Society of Sports Nutrition, 16(1), 1-8.
  • Rizzo, N. S., Jaceldo-Siegl, K., Sabate, J., & Fraser, G. E. (2013). Nutrient profiles of vegetarian and nonvegetarian dietary patterns. Journal of the Academy of Nutrition and Dietetics, 113(12), 1610-1619.
  • Rosenson, R. S., & Song, W. L. (2019). Egg yolk, source of bad cholesterol and good lipids?. The American Journal of Clinical Nutrition, 110(3), 548-549.
  • Tonstad, S., Butler, T., Yan, R., & Fraser, G. E. (2009). Type of vegetarian diet, body weight, and prevalence of type 2 diabetes. Diabetes care, 32(5), 791-796.

Lacto-Ovo Vegetarianism Studies

Date

Name of Paper

Journal Name

Link to Paper

2021

Effects of lacto-ovo-vegetarian diet vs. standard-weight-loss diet on obese and overweight adults with non-alcoholic fatty liver disease: a randomised clinical trial

Archives of Physiology and Biochemistry

2021

Plant-based dietary patterns are associated with lower body weight, BMI and waist circumference in older Australian women

Public Health Nutrition

2021

The effect of plant-based dietary patterns on blood pressure: a systematic review and meta-analysis of controlled intervention trials

Journal of Hypertension

2020

Effects of a Lacto-Ovo-Vegetarian Diet on the Plasma Lipidome and Its Association with Atherosclerotic Burden in Patients with Coronary Artery Disease—A Randomized, Open-Label, Cross-over Study

Nutrients

2019

Exercise capacity of vegan, lacto-ovo-vegetarian and omnivorous recreational runners

Journal of the International Society of Sports Nutrition

2019

Diet quality of vegetarian diets compared with nonvegetarian diets: a systematic review

Nutrition Reviews

2019

Health Status of Female and Male Vegetarian and Vegan Endurance Runners Compared to Omnivores—Results from the NURMI Study (Step 2)

Nutrients

2018

Impact of a 3-Months Vegetarian Diet on the Gut Microbiota and Immune Repertoire

Frontiers in Immunology

2017

Environmental impact of omnivorous, ovo-lacto-vegetarian, and vegan diet

Scientific Reports

2017

Adherence to a Vegetarian Diet and Diabetes Risk: A Systematic Review and Meta-Analysis of Observational Studies

Nutrients

2017

Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies

Critical Reviews in Food Science and Nutrition

2016

Position of the Academy of Nutrition and Dietetics: Vegetarian Diets

Journal of the Academy of Nutrition and Dietetics

2013

Vegetarian diets and incidence of diabetes in the Adventist Health Study-2

Nutrition, Metabolism and Cardivascular Diseases

2013

Reduced Risk for Metabolic Syndrome and Insulin Resistance Associated with Ovo-Lacto-Vegetarian Behavior in Female Buddhists: A Case-Control Study

PloS one

2013

Nutrient Profiles of Vegetarian and Nonvegetarian Dietary Patterns

Rheumatology

2012

Cardiovascular Disease Mortality and Cancer Incidence in Vegetarians: A Meta-Analysis and Systematic Review

Annals of Nutrition and Metabolism

2012

Vegetarian diets and blood pressure among white subjects: results from the Adventist Health Study-2 (AHS-2)

Public Health Nutrition

2010

Lifestyle-related disease in Crohn’s disease: Relapse prevention by a semi-vegetarian diet

World Journal of Gastroenterology

2009

Type of Vegetarian Diet, Body Weight, and Prevalence of Type 2 Diabetes

Diabetes Care

2004

Insulin sensitivity in Chinese ovo-lactovegetarians compared with omnivores

European Journal of Clinical Nutrition

2001

Vascular dilatory functions of ovo-lactovegetarians compared with omnivores

Atherosclerosis

1994

Nutrient intake of endurance runners with ovo-lacto-vegetarian diet and regular western diet

Z Ernährungswiss

1989

Cardiovascular disease risk factors in free-living men: comparison of two prudent diets, one based on lactoovovegetarianism and the other allowing lean meat

The American Journal of Clinical Nutrition

1986

Nutrient intake, blood pressure, serum and urinary prostaglandins and serum thromboxane B2 in a controlled trial with a lacto-ovo-vegetarian diet.

Journal of hypertension

1986

Vegetarian diet in mild hypertension: a randomised controlled trial.

Br Med J (Clin Res Ed)

1985

A RANDOMIZED CONTROL TRIAL OF A VEGETARIAN DIET IN THE TREATMENT OF MILD HYPERTENSION

Clinical and Experimental Pharmacology and Physiology

1983

BLOOD-PRESSURE-LOWERING EFFECT OF A VEGETARIAN DIET: CONTROLLED TRIAL IN NORMOTENSIVE SUBJECTS

The Lancet

1980

Cortical bone density of adult lacto-ovo-vegetarian and omnivorous women.

Journal of the American Dietetic Association

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