Are vegetarian diets healthier?

By Amanda Johnson 17/06/2013 8


New research published earlier this month in JAMA Internal Medicine (3 June 2013) has found that vegetarian diets are associated with lower all-cause mortality.

A total of 96,469 Seventh-day Adventist men and women were recruited between 2002 and 2007, from which an analytic sample of 73,308 participants remained after exclusions. Study participants filled out a diet and lifestyle questionnaire at the start of the study, then every two years after that, filled out hospital history forms and listed any hospitalizations and diagnoses of cancers, stroke, heart attack and diabetes during the previous two years.

According to the researchers,

Research data showed a progressive weight increase from a total vegetarian diet toward a non-vegetarian diet. Additionally, levels of cholesterol, diabetes, high blood pressure, and the metabolic syndrome all had the same trend – the closer you are to being a vegetarian, the lower the health risk in these areas. In the case of type 2 diabetes, prevalence in vegans and lacto-ovo vegetarians was half that of non-vegetarians, even after controlling for socioeconomic and lifestyle factors.”

Compared to non-vegetarians, the vegetarians watched less television, slept more hours per night, consumed more fruits and vegetables, consumed less saturated fat, and typically ate foods with a low glycaemic index, such as beans, legumes and nuts.

The study has attracted some media interest, with headlines in the UK Daily Mail, for example, asking if vegetarianism is the secret to a longer life.

This type of research is nothing new. Almost 20 years ago the Oxford Vegetarian Study (Thorogood et al., 1994) found a significant reduction in mortality from cancer and overall mortality in non-meat eaters. There was also a lower rate of ischaemic heart disease among vegetarians. In this study though, it was difficult to disentangle which features of the vegetarian diet were responsible for the protective effect, and the authors concluded their data did not provide justification for encouraging omnivores to change to a vegetarian diet as there were several attributes of the vegetarian diet, apart from not eating meat, which might reduce risk

An editorial entitled Should we all be vegetarians?, by Dr Robert B Baron from the University of California, accompanies this latest study. Dr Baron points out that like all observational studies, this one provides associations and not cause and effect evidence.

As with many of these studies, the avoidance or limitation of meat may simply be a marker for a healthier diet and lifestyle. And, as Dr Baron comments, “although the authors use state-of-the-art approaches to adjust for potential confounders, one can never be sure that there are not other factors influencing the association between vegetarian diets and mortality”

Commenting to HeartWire, Dr Robert H Eckel from the University of Colorado agrees. “We need to put this study into perspective. Is a vegetarian diet heart healthy? Probably yes. Should people convert to a vegetarian diet based on this study? Absolutely not. I think they need to look at their overall diet and make sure it is consistent with what we know about diet and heart disease.”

I’d agree. I think the key is to have a healthy balanced diet and an active lifestyle, whether or not you eat meat. For those who do eat meat it’s important to stick to the appropriate portion sizes, and to have very lean cuts. For those who choose to follow a vegetarian or vegan eating pattern the most important consideration is to ensure the diet is balanced and, in particular, that the important nutrients that meat would have provided, such as iron, are provided by alternative foods, such as nuts, seeds, lentils, cooked dried beans and tofu.

To reduce risk of cardiovascular disease and cancer, include plenty of wholegrains, fruits and vegetables in the daily diet. It’s also important to consume foods that are low in total fat, saturated fats and trans fats. If meat is eaten it should be very lean. Poultry should be eaten without skin, and dairy products should be low-fat. In addition, a regular intake of fish (once or twice a week) will boost intakes of omega-3 fatty acids, and will help lower the risk heart disease, along with other dietary and lifestyle strategies.


8 Responses to “Are vegetarian diets healthier?”

  • There are elements of the study that trouble me. For example, I am struggling to see what difference a vegetarian diet makes to the hours of television one watches. Were the people studied matched by sex and age, etc with people who ate a varied diet that included meat and were careful about what they ate.

    I think your last two paragraphs are the most important part of the post. It would be interesting to see a comparison of health outcomes in people who follow your suggestions in the final paragraph, compared with vegetarians.

  • Yes, I think when comparing groups of people and declaring one group healthier, it is important to look at all aspects of diet and lifestyle. Hours of television watching are one marker for sedentary behaviour, and of course activity is an important part of a healthy lifestyle.

    Yes, it would be interesting to look at a standard group of people who watch little television, sleep plenty hours per night, consume plenty fruits and vegetables and little fat, and who eat foods such as beans, legumes and nuts – then to divide these people into those who eat no meat and those who eat the recommended portion sizes of lean meat as part of a balanced diet and an active lifestyle. I wonder what the differences in health would be then. Probably not that great.

  • What about Colin Campbell’s The China Study for demonstrating that both meat and dairy products are bad for you? I haven’t found any credible criticism of it and can only think that other scientists are ignoring it because they can’t criticize it? Campbell has a new book out now “Whole” that explains how the system is rigged to keep people eating things that corporations churn out even though they aren’t healthy– the resulting diseases are good for health care corporations and big pharma as well as the corporations that make the so called food in the first place.

    President Bill Clinton went vegan except for occasional fish because he had heart disease that couldn’t be helped by more operations. And he seems to be doing well–what does this say to you? Dean Ornish has proven that an essentially vegan diet with low fat and whole grains reverses heart disease.

  • Yes, it would be interesting to look at a standard group of people who watch little television, sleep plenty hours per night, consume plenty fruits and vegetables and little fat, and who eat foods such as beans, legumes and nuts – then to divide these people into those who eat no meat and those who eat the recommended portion sizes of lean meat as part of a balanced diet and an active lifestyle. I wonder what the differences in health would be then. Probably not that great.

    Given the quantity of participants they described the data could be filtered for this and probably still provide significant results.

  • I think the problem is that while the sample size if large, it’s drawn from Seventh-Day Adventists only. To what extent we can regard these as representative of general population is a little opaque.

    From what I can recall, this tends to be the recurrent problem with studies of vegetarians. They don’t just differ from meat-eaters in diet, but systematically in areas like lifestyle.

    We do seem to have evolved to cope with a range of diets, and I suspect it is the intersection of extreme diets with lifestyle that inflates health problems. Eating meat 2-3 times a day with lots of saturated fats and sugars is pushing the envelope on what we evolved to eat. I would expect you can manage a healthy diet with or without meat, so long as it remained balanced and supported by a less sedentary lifestyle.

  • So I checked Amanda’s link and here are the flags that popped up: this guy doesn’t seem to have written any publications in any medical journals– the link he gives to an article he wrote is on the Weston-Price foundation web site. WP is run by Sally Fallon– the web site says she is a nutrition researcher but you look her up and she only has a degree in English. My husband spent some time trying to have discussions with her over email and she doesn’t seem to want to have a meaningful conversation but instead just puts down whatever you send her. I don’t know who this guy is but if he is the only critic of the China Study then I’d say Colin Campbell doesn’t have much to worry about. He’s just written another book called “whole” that explains about what is going on with research, the media and advocacy organizations that is worth the read if you’re really interested in this. It is easy for people to just make it seem too complicated and people are put off and quit looking into it and that is what the dairy, meat, pharmaceutical and medical industries want.

  • Hmm… That first paragraph in my comment above was meant to be a blockquote (and looking at the source the tags are still there). Note to self: quote with quotemarks too.

    Anyway, that was in reply to Amanda Johnson.