What About Canned Fruit?

Food cans used to be soldered with lead compounds—so much so that people living off of canned food may have died from lead poisoning. Thankfully, this is no longer a problem in the United States. Lead contamination was one of the first priorities of the Food and Drug Administration back in 1906, before it was even called the FDA. Newspapers now have online archives going back a century so we can read about landmark historical events like “FDA Proposes Lead-Soldered Cans Be Banned” from way back yonder in…1993. So even though it was a priority in 1906, the ban didn’t actually go into effect until 1995. Evidently it was complicated because lead solder was “grandfathered” in as a “prior-sanctioned” substance.

Now that the lead is gone, though, are canned foods healthy? It depends primarily on what’s in the can. If it’s SPAM or another processed meat product, for instance, I’d probably pass.

What about canned fruit? We know fruits and vegetables in general may help protect us from dying of cardiovascular disease, and, when it comes to preventing strokes, fruit may be even more protective. But whether food processing affects this association was unknown, as I discuss in my video Is Canned Fruit as Healthy? One study found that unprocessed produce, mostly apples and oranges, appeared superior to processed produce. But that study focused mainly orange and apple juice. It’s no surprise whole fruit is better than fruit juice.

What about whole fruit when it is in a can? Dietary guidelines encourage eating all fruit whether it’s fresh, frozen, or canned, but few studies have examined the health benefits of canned fruit…until now. Canned fruit did not seem to enable people to live longer. In fact, moving from fresh or dried fruit to canned fruit might even shorten one’s life. Therefore, perhaps dietary guidelines should stress fresh, frozen, and dried fruit rather than canned.

Why the difference? While there’s no longer lead in cans these days, there is bisphenol A (BPA), the plastics chemical used in the lining of most cans. BPA can leach into the food and might counterbalance some of the fruits’ benefits. Recently, for example, blood levels of this chemical were associated with thickening of the artery linings going up to the brains of young adults. Canned fruit is often packed in syrup, as well, and all that added sugar and the canning process itself may diminish some nutrients, potentially wiping out 20 to 40 percent of the phenolic phytonutrients and about half of the vitamin C.

Maybe one of the reasons citrus appears particularly protective against stroke is its vitamin C content. It appears the more vitamin C in our diet and in our bloodstream, the lower the risk of stroke. And the way to get vitamin C into the bloodstream is to eat a lot of healthy foods, like citrus and tropical fruits, broccoli, and bell peppers. “Therefore, the observed effect of vitamin C on stroke reduction may simply be a proxy for specific foods (eg, fruits and vegetables) that causally lower stroke” risk. How could the researchers tell? Instead of food, they gave people vitamin C pills to see if they worked—and they didn’t.

This might be because citrus fruit have all sorts of other compounds associated with lower stroke risk, proving that the whole is greater than the sum of its parts. You can’t capture Mother Nature in a pill. It’s like the apocryphal beta-carotene story. Dozens of studies showed that people who ate more beta-carotene-rich foods, like greens and sweet potatoes, and therefore had more beta-carotene circulating in their system, had lower cancer risk. What about beta-carotene supplements instead of whole foods? Researchers tried giving beta-carotene pills to people. Not only did they not work, they may have even caused more cancer. I assumed the National Cancer Institute researcher who did this study would conclude the obvious: produce, not pills. But, no. Instead, the researcher questioned whether he should have tried lower dose pills, alpha-carotene pills, pills with other phytochemicals, or maybe multiple combinations. After all, he said, “[i]t is likely that neither the public nor the scientific community will be satisfied with recommendations concerned solely with foods…”

Check out my other videos on the can-lining chemical BPA, including:

Is fresh fruit really that healthy? See:

Is it possible to get too much of a good thing? See How Much Fruit Is Too Much?.

Now that there’s no more lead in the cans, are there any other ways we’re exposed to the toxic heavy metal? I did a whole series on lead, which you can watch. See also:

I close with yet another screed against reductionism. For more on that, see my videos Why Is Nutrition So Commercialized? and Reductionism and the Deficiency Mentality.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Why There Is so Much Commercial Corruption in Nutrition

The prevalence of chronic diseases such as diabetes has skyrocketed, as has the number of articles published about diabetes in medical journals. “Why does our wealth of academic knowledge not translate more directly to improving the human condition?” Perhaps our over-attachment to the reductionistic mindset that proved so successful with acute deficiency diseases may actually represent an obstacle to success battling chronic disease.

These days, health seems to have been reduced to a highly commercialized commodity, in which we’re marketed all sorts of high-cost, high-tech tests and treatments of dubious value with substantial risks attached. “This is worrisome because most of the things that make us healthy and keep us healthy are cheap and largely available without professional help or commercial prodding.” This isn’t to say modern medicine can’t work miracles, but what about the big picture? That is, what about the 80 percent of death and disability caused by preventable diet-related diseases?

What about the field of nutrition? In my video Why Is Nutrition So Commercialized?, I discuss how it’s become about profits and products, and extracting nutrients from whole foods so they can be repackaged and marketed. But food is best eaten whole. Eat the broccoli and the blueberries, not some broccoberry supplement. But the reason there aren’t more studies on whole foods is fairly obvious: You can’t patent them. Why should a company spend a lot of money, time, and effort to convince you to buy broccoli when any other company can sell it to you? That’s why the field of nutrition can be more about marketing profitable products than educating people about the fundamentals of health and wellness. For example, the benefits of whole grains over refined grains is commonly attributed to the fiber, which enables the food industry to whip out fiber-fortified Froot Loops and make you feel all better.

Let’s consider this ingenious study: Burkitt and colleagues thought the extraordinarily low rates of killer chronic diseases in sub-Saharan Africa were due to all the whole, plant foods they were eating. This turned into the fiber hypothesis, the reductionistic thought that fiber must be the magic bullet active ingredient. What happens if we put it to the test? What if we compared two groups of older women, both getting around six grams of grain fiber a day, but one group mostly from whole grains and the other mostly from refined grains? Who do you think lived longer? If it was just the fiber, there shouldn’t be much difference because both groups ate about the same amount. In fact, the whole grain group lived longer and with a significantly lower mortality rate, which implies that it may be all the other wonderful things in whole plant foods “linked to fiber [that] may confer important health benefits above and beyond effects of the fiber itself.” That’s why fiber supplements wouldn’t be expected to offer the same benefit.

Indeed, food, not nutrients, is the fundamental unit in nutrition.

As Dr. David Katz has pointed out, “Our culture doesn’t want to hear that the active ingredient in broccoli is broccoli—it wants to know what supplement it can take.”

This is part of my extended series on the reductionist trap, which includes:

The Five to One Fiber Rule still holds, though, since it’s an indication of how heavily processed a product is.

There are two sides to the intellectual property argument when it comes to food. I explore both in Plants as Intellectual Property: Patently Wrong?.

And, of course, this is why I always recommend Taking Personal Responsibility for Your Health.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

How to Boost DNA Repair with Produce

“In the light of strikingly consistent observations from many epidemiological [population-based] studies, there can be little doubt that the habitual consumption of diets high in fruits and vegetables helps to reduce the risk of development of degenerative diseases, including many types of cancers.” Not satisfied with merely telling people to eat their fruits and veggies, scientists want to know the mechanism. I discuss this topic in my Which Fruits and Vegetables Boost DNA Repair? video.

Not just vehicles for antioxidants, fruits and vegetables contain innumerable phytonutrients that can boost our detoxification enzymes, modulate gene expression, and even modulate DNA repair pathways. “Until fairly recently…it was generally assumed that functions as important as DNA repair were unlikely to be readily affected by nutrition,” but, if you compare identical twins to fraternal twins, only about half to three quarters of DNA repair function is genetically determined. We may be able to control the rest.

“It is estimated that, on average, there are 800 incidents of DNA damage [in our bodies] per hour,” which is about 19,000 hits to our DNA every day. What’s more, “that DNA damage can cause mutations and give rise to cancer, if not repaired.” Thankfully, “the regulation of [DNA] repair can be added to the list of biological processes that are influenced by what we eat—and, specifically, that this might constitute part of the explanation for the cancer-preventive effects of many plant-based foods.”

Any plants in particular? Nine fruits and vegetables were tested to find out which ones were better able to boost DNA repair: lemons, persimmons, strawberries, oranges, choy sum (which is like skinny bok choy), broccoli, celery, lettuce, and apples. Which ones made the cut? Lemons, persimmons, strawberries, broccoli, celery, and apples all conferred DNA protection at very low doses.

Lemons, for example, were found to cut DNA damage by about a third. Was it the vitamin C? No. Removing the vitamin C from the lemon extract did not remove the protective effect. However, if you first boiled the lemon for 30 minutes, the protective effect was lost.

If it’s not the vitamin C, what might it be? That’s the subject of my video Citrus Peels and Cancer: Zest for Life?

Surprised that the lemon benefit was abolished by cooking? Find out which vegetables it may be best to eat raw in Best Cooking Method.

What about cooked versus raw garlic? See my video Inhibiting Platelet Activation with Garlic and Onions.

For more on DNA protection and repair, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: