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Lacto-Ovo Vegetarian Diet: Limited Evidence

This content was last updated on April 13, 2021

The Cancer Research

Beyond meeting the recommendation for a plant-based diet, evidence is too limited to allow any conclusions about a lacto-ovo vegetarian diet as a specific choice for reducing cancer risk, according to AICR’s Third Expert Report.

Current Evidence

  • Overall Cancer. Evidence from long-term observational population studies shows that vegetarian diets as a whole (which includes lacto-ovo vegetarian diets as well as vegan diets and diets that include meat or fish up to once a week) are consistently linked to lower risk of cancer compared to diets that include meat and fish more than once a week. Lacto-ovo vegetarian diets specifically show a similar association with lower overall cancer risk.
  • Digestive Tract Cancers. In a large U.S. study, compared to non-vegetarian diets, lacto-ovo vegetarian diets were linked with lower risk of overall gastrointestinal tract cancers. Some evidence suggests this may include lower risk of colorectal cancer. Such a link makes sense, since strong evidence links greater consumption of dairy products and of dietary calcium with lower risk of colorectal cancer.
Source: Important Insights

Ongoing Areas of Investigation

  • More on Lacto-Ovo Diet

    What you do eat as well as what you don’t eat counts. Studies of vegetarian diets and their association with cancer risk sometimes show slightly different results. A closer look suggests that part of the difference may reflect the importance of specific food choices.

    • People who follow a vegetarian diet but include frequent use of sweets, refined grains, sugar-sweetened beverages and unhealthy choices of added fats do not show as much health benefit. People following a vegetarian diet who limit these foods and include abundant vegetables, legumes (dry beans, peas, lentils, and soy foods), nuts and seeds tend to show lowest risk of cancer and heart disease.
    • Overall, people in studies who follow vegetarian diets tend to also consume little or no alcohol, avoid tobacco, get regular physical activity, and maintain a healthy weight. Although researchers try to adjust for these factors in their statistical analysis, the overall lifestyle of people who follow vegetarian diets may be reflected in the health benefits seen.

    Weight as a complicating factor. People following a vegetarian diet are less likely to have overweight or obesity, which is another way that these eating habits help reduce risk of cancer. But simply eliminating all animal foods does not necessarily lead to a healthy weight for people who eat more calories than they need, especially if they frequently include large portions of foods or drinks high in added sugars or fats.

  • Tips for Following a Lacto-Ovo Vegetarian Diet
    • Lacto-ovo vegetarian diets are a specific type of vegetarian diet that avoids meat, fish and poultry, but includes moderate amounts of dairy products and/or eggs.
    • Lacto-ovo vegetarian diets offer lots of flexibility for a plant-based diet that meets nutrient needs and tastes delicious. Don’t rely only on dairy products and eggs to meet your protein needs, though. Include plenty of plant foods like dry beans, lentils, soy foods, nuts and seeds, too, since they provide protein along with a different array of vitamins, minerals and phytochemicals.
    • Lacto-ovo vegetarian diets fit with many different style of cooking from around the world, including a small amount of cheese, yogurt or eggs with plant foods like dry beans, lentils, whole grains, and vegetables.


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  2. World Cancer Research Fund/American Institute for Cancer Research. Diet, Nutrition, Physical Activity and Cancer: a Global Perspective. Continuous Update Project Expert Report 2018. Available at dietandcancerreport.org.
  3. Orlich MJ, Chiu THT, Dhillon PK, et al. Vegetarian Epidemiology: Review and Discussion of Findings from Geographically Diverse Cohorts. Advances in Nutrition. 2019;10(Supplement_4):S284-S295.
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  8. World Cancer Research Fund/American Institute of Cancer Research. Continuous Update Project Expert Report 2018. Meat, fish and dairy products and the risk of cancer. Available at: dietandcancerreport.org.