Fruits and Vegetables DON’T Prevent Heart Disease

Fruit and vegetable consumption does not seem to reduce the risk of heart attacks (coronary heart disease), according to a recent literature review by French epidemiologists.

I recently wrote about a study that found no overall reduced risk of cancer via consumption of fruits and vegetables.

Heart attacks and cancer are the first and second leading causes of death in the developed world.

So just why, again, are we supposed to be eating our fruits and vegetables?

Here’s most of the abstract written by the epidemiologists:

This Review summarizes the evidence for a relationship between fruit and vegetable consumption and the occurrence of coronary heart disease…Most of the evidence supporting a cardioprotective effect comes from observational epidemiological studies; these studies have reported either weak or nonsignificant associations.  Controlled nutritional prevention trials are scarce and the existing data do not show any clear protective effects of fruit and vegetables on coronary heart disease.  Under rigorously controlled experimental conditions, fruit and vegetable consumption is associated with a decrease in blood pressure, which is an important cardiovascular risk factor.  However, the effects of fruit and vegetable consumption on plasma lipid levels, diabetes, and body weight have not yet been thoroughly explored.  Finally, the hypothesis that nutrients in fruit and vegetables have a protective role in reducing the formation of atherosclerotic plaques and preventing complications of atherosclerosis has not been tested in prevention trials.  Evidence that fruit and vegetable consumption reduces the risk of cardiovascular disease remains scarce thus far.

What do they mean by controlled prevention trials?  Here’s an example.  Find 20,000 people with similar characteristics.  Randomly assign half of them to eat significantly more fruits and vegetables, and make sure they do it.  The other half eats their usual way, and make sure they do it.  Analyze the entire group’s health and food consumption after 10 years and see which half has more or less heart disease.   

Such a study is very difficult and costly.  Even if the fruit and veggie group had less heart disease, someone would argue that the heart benefit was gained because of what they cut out of their eating to make way for the fruits and veggies!  “They quit eating Cheetos; that’s why they had fewer heart attacks.”

Bottom Line

Fruits and vegetables don’t prevent heart disease, according to these researchers.

Fruits and vegetables are components of overall healthy diet patterns such as the Mediterranean diet, the DASH diet, and the “prudent diet.”  Is it possible they reduce the risk of stroke, the second leading cause of death?  I’ll leave that for another day.

I’m starting to think if I read enough nutritional literature, I won’t know anything with certainty.

Steve Parker, M.D. 

Dauchet L., Amouyel, P., and Dallongeville, J. (via MedScape).  Fruits, vegetables and coronary heart disease.  Nature Reviews Cardiology, 6 (2009): 599-608.  doi: 1011038/nrcardio.2009.131

11 Comments

Filed under coronary heart disease, Fruits, Vegetables

11 responses to “Fruits and Vegetables DON’T Prevent Heart Disease

  1. This reductionist viewpoint of epidemiologists is starting to wear thin. Surely, there is more to nutrition than just eating fruits and vegetables, ie total caloric load, protein, fat, etc. This reminds of when I used to do research in animals and we’d tinker around with different diets (high fat/low fat, high salt/low salt, etc). The nutritionist at the manufacturer would always keenly point out, “what do you want to replace it with?” It’s as much about what’s NOT in the diet as what is in there.

    If one takes this data at face value, one begins to walk away with the notion that diet is irrelevant which I have a very hard time believing considering what happens to multiple chronic diseases once a society adopts a typical western diet.

    • Isaac-

      I wonder if the “bad element” (if there’s only one?!) in the typical western diet is: highly processed, refined foods, mostly carbohyrate.

      I’m talking about sugar (including high fructose corn syrup), white flour, corn meal, etc.

      We’re starting to see lots of blogospheric criticism of “industrial oils,” like soybean and corn oils, upsetting the omega-6:omege-3 ratio. I’ve not studied that in any detail.

      -Steve

      • In so much as those deliver whopping amounts of calories that shortcircuit your taste buds and liver, I’d agree.

        The omega 6/3 ratio is one of those theories that may or may not pan out with more data. Aside from the historical/evolutionary component, I think they’re something to it based on two pieces of data. 1 – supplementing with fish oil is able to alter disease states, especially cardiovascular. 2 – aspirin is also able to do the same by blocking arachidonic acid release. The data seem to be describing a two way street to me – increase omega 3, decrease cv disease and likewise, decrease omega 6 release, decrease cv disease. I know some rheumatologists use lovaza off label, citing the same logic with cv disease. Whether that pans out with the oils, I’m not going to put any data on that just yet.

        I think the unnoticed and bigger component of the story is that as recently as 50-100 years ago, our major sources of protein (meat, fish, eggs) were all much higher in omega 3. Now with modern farming practices relying heavily on corn, they’re much higher in omega 6. Eggs are now readily available with huge amounts of omega 3 (some as much as tuna), salmon has to be wild and not farm raised, but beef has to be grass fed and that is not remotely economically feasible for the average family.

  2. Steve Parker, M.D.

    Very insightful, Isaac.

    BTW, I’ve added your blog – “The Heart Is a Lonely Hunter: Tales from the training of a physician” – to my blogroll.

    [Readers of comments here know Isaac as highly intelligent and well-informed nutritionally. He’s also a bit of poet and philosopher. A Renaissance man compared to most physicians.]

    -Steve

    • You’re too kind.

      I had a thought about your digging into the research where dietary studies oftentimes seem to indicate that diet IS meaningless. It led me to two possibilities.

      1 – It’s all about the number of calories. Caloric restriction increases lifespan in multiple animals. Perhaps, one can eat all the fruit in the world but if you’re combining it with large numbers of calories, it won’t make one iota of a difference.

      2 – Lifestyle matters. Perhaps when cultures adopt a western diet and then see a rise in CV disease, diabetes, obesity, etc., it’s also about the habits that go along with it. Maybe those much harder things to quantify about a western lifestyle – stress, less exercise, fast paced, etc – are confounding the issue.

      Do you know if mediterranean diets have data in western cultures where the lifestyle is different?

      I still hold that the DASH diet will reduce cv outcomes IF bp reductions are observed. If it doesn’t, then we know absolutely nothing about physiology. But that may be a big IF based on this paper.

      http://www.6minutes.com.au/html/selfmanage/vault/pdf/DASHdieteditorial.pdf

      • There are positve studies on the Mediterranean diet in about eight different countries over three continents. An Indo-Mediterranean diet study was popular about five years ago. Indo as in Indian (Asian, not Native American).

        -Steve

      • Steve

        Definitely studies in Australia of Greek populations and the following generations – resulting in the suspected outcome (as the diet changes, so does the health outcomes)
        steve
        Oz

  3. Vernon

    Recently Pomegranate has become one of the most studied super foods. Preliminary laboratory research conducted on mice revealed that pomegranate was effective in reducing heart disease risk factors such as LDL Oxidation, macrophage oxidative status, and foam cell formation, all of which leads to hardening of the arteries and cardiovascular diseases.

  4. allyson

    Steve, I greatly appreciate your in depth research on the topic of nutrition and general well-being. And the whole “fruit and veggie” consumption assumption is definitely becoming a complete farce in the west, because: a) most are GMO anyhow, and b) people believe that they can eat any processed garbage they want if they just eat fruit and vegetables too!
    I don’t know if you are from the U.S, Steve, but many of the so-called illnesses that we face are simply vitamin and mineral deficiencies. For example, anemia results from iron deficiency, but how can I be lacking in something, while becoming more of this “condition” simultaneously? I’m sorry, but that is a little too much double-think, even for me. Well, that’s why doctors here call many problems “conditions,” because it really isn’t a problem, it is a state that your body is in at the moment, which can usually be “treated” with a change in diet. However, when you are convinced that something is wrong with you, you agree to the nice perscription, side effects including: high blood pressure, stroke, “thoughts of suicide,” etc, which you will then eventually NEED for your health, since most perscription drugs are highly addictive.
    I know this became a little off course, and I am not trying to speak badly of western doctors, but we are led to believe, especially in the U.S. with drug ads around every corner, that things like cancer and heart disease will happen to everyone eventually, and all we need to do is “race for the cure,” buy ‘pink’ merchandise, and everything will be wonderful, even though the cancer INDUSTRY is still a $200 billion dollar/year one. What people REALLY need to do is research people like yourself for information on how to remain/become healthy, instead of some comapny’s website, which would be like me telling you to go look at my website to prove how great I am (by the way, I also made the website saying all these things and hired the scientists and researchers to give their thumbs up, but that’s all kosher, right?).
    I guess my main question is if you think that medical research in the U.S. is flawed and/or biased in order to suit certain pharmaceutical companies’ interests?

    Allyson – TX

  5. allyson

    Steve,

    Thank you for taking the time to reply, and I really appreciate the recommendation! It was right up my alley.
    Keep up the great work on the site, and take care!

    Allyson