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:

Vitamin C Pills Put to the Test for Cancer

Vitamin C “is no stranger to controversy, as evidenced by the fact that over 40 years lapsed” from the time citrus fruits were shown to cure scurvy in the 1700s and the widespread implementation of eating citrus to save lives. Is it possible we’re in the midst of a similar 40-year lag with research in the mid-1970s purporting to show that terminal cancer patients treated with vitamin C lived 4 times longer and sometimes 20 times longer? I explore this in my video Vitamin C Supplements for Terminal Cancer Patients.

Researchers at the venerable Mayo Clinic decided to put vitamin C to the test, and they failed to show any benefit. The survival curves for both groups of patients were essentially identical. In fact, the one success story, a man with end-stage pancreatic cancer who had shown no response to any previous attempts at chemotherapy but started improving and was still alive five years later, was one of the patients who got the sugar pill placebos. It was official: Vitamin C didn’t work. “The apparently positive results reported…almost certainly resulted” from systematic bias in terms of which historic controls were chosen to compare with the treatment group, read the accompanying National Cancer Institute editorial.

Linus Pauling disagreed, arguing that the prior chemotherapy in nearly all the Mayo Clinic study patients may have negated the effect of the vitamin C. If the vitamin C works by boosting your immune system but your immune system is first destroyed by chemo, the thinking goes, no wonder it didn’t work. In the original vitamin C study that showed remarkable benefit, only 4 out of the 100 patients had ever received chemo. The Mayo Clinic researchers were skeptical, but “Pauling had a legendary reputation for being right about all sorts of things,” so “one might perhaps do worse than rely at least partly on Pauling’s awesome intuition.” Thus, a second, randomized, double-blind, placebo-controlled study was performed on patients with advanced cancer, but, this time, those who had no prior chemotherapy.

Again, it was a spectacular failure.

Researchers found no measurable response. The cancer in the vitamin C group progressed just as rapidly, and the patients on the placebo sugar pills lived just as long. In fact, if anything, the sugar pill group lived longer. At two years, everyone in the vitamin C group had died, but there were still a few survivors in the placebo group who lived at least past three years. The researchers concluded that “high-dose vitamin C therapy is not effective against advanced malignant disease, regardless of whether the patient has had any prior chemotherapy.”

Because the Mayo studies were taken as definitive, the medical community concluded that vitamin C was useless. However, in the Mayo Clinic studies, they gave the vitamin C orally in supplements, not intravenously. In retrospect, the route of administration may have been key.

In the original study, Pauling and his researchers started out infusing 10 grams of vitamin C a day intravenously, whereas in both of the Mayo studies designed to replicate the protocol, the researchers just gave people vitamin C supplements to take orally. Patients were sent home to swallow 20 capsules a day. They got the same dose, but 10 grams given orally is not the same thing as 10 grams given intravenously. They can’t be blamed for their ignorance, though. This fact wasn’t discovered until decades later.

It turns out vitamin C concentration in our bloodstream is tightly controlled, such that if you try to swallow more than you’d get eating five servings of fruits and vegetables, your body cuts down on the absorption in the intestine. For example, if you go from eating 200 mg to eating about ten times more (2,500 mg), the level in your bloodstream only goes up 3 mg per liter or quart of blood. “In contrast, because intravenous injection bypasses the intestinal absorption system,” it can result in super high blood concentrations—as in 100 to 200 times the level you can achieve taking vitamin C orally. Maybe that explains why the original studies seemed so promising but the follow-up studies were so disappointing. This raises the controversial question of the re-evaluation of vitamin C in cancer treatment. Researchers responded to the challenge and took up the mantle, and I discuss this in my video The Role of Vitamin C in the Treatment of Terminal Cancer.


To learn more about the history of vitamin C and cancer, see Intravenous Vitamin C for Terminal Cancer Patients.

To learn more about vitamin C, see Do Vitamin C Supplements Prevent Colds But Cause Kidney Stones? and What Is the Optimal Vitamin C Intake?.

Can eating citrus protect against cancer? Find out in Citrus Peels and Cancer: Zest for Life?.

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:

The Vitamin C Cancer Study that Started It All

In 1975, a remarkable case was reported of a 42-year-old man suffering from a malignant form of non-Hodgkin’s lymphoma who experienced a dramatic regression of the cancer after being given large doses of vitamin C intravenously, as I discuss in my video Intravenous Vitamin C for Terminal Cancer Patients. He seemed cured, so they stopped the vitamin C. The cancer came surging back. They restarted the vitamin C and apparently induced a second complete remission. Sometimes cancer does just spontaneously regress—it’s rare, but not unheard of. So, one could argue that the first remission was spontaneous, and it was just a coincidence that it happened when they started the vitamin C. However, given the trajectory the cancer was on, followed by the rapid remission, followed by the relapse when the vitamin C was stopped, followed by a second remission once restarted, the case strongly suggests that the vitamin C had something to do with the cancer’s remission.

Now, multiple spontaneous regressions do exist. There was a recent case, for example, of a woman with cervical cancer who appeared to be cured with radiation and chemo. Her cancer came back and she refused further treatment. Yet, the tumors disappeared on their own, then came back, then disappeared, then came back, then disappeared, then came back, and then disappeared for a fourth spontaneous remission—and all that was with no apparent treatment at all. So, it’s possible this vitamin-C case is just a crazy, coincidental fluke, and the vitamin C didn’t help at all. You never know until you put it to the test.

Researchers enlisted the help of Linus Pauling, who they considered the greatest chemist of the 20th century and who was known to be interested in vitamin C. If he couldn’t get funding, nobody could get funding. And he couldn’t get funding. They went to the National Cancer Institute with promising data on the first 40 cancer patients they had treated with vitamin C and asked that the institute carry out or fund a randomized double-blind trial. In this type of trial, they would take a group of incurable cancer patients for whom medicine has nothing more to offer, randomly split them into two groups, and infuse one group with vitamin C and the other group with something like saline, basically water, and then see who lives the longest. Neither the patients nor the doctors would know who got the vitamin C and who got the saline to eliminate bias and placebo effects. The researchers and Pauling went back year after year after year asking for grants to study it themselves if the National Cancer Institute wasn’t going to do it, and they got rejected year after year after year. So, they scraped up whatever funds they could find and did their best with what they had. They published their findings in 1976.

The researchers didn’t have a controlled trial, but, by that point, they had treated a hundred terminal cancer patients with vitamin C. So, they compared their progress to that of a thousand similar patients who did not get vitamin C. For each patient treated with vitamin C, the researchers found ten patients about the same age and with the same kind of cancer who had been treated at the same hospital but who had not received the vitamin C infusions. What did they find? In patients with terminal breast cancer, within a hundred days, more than 80 percent of the women in the control group were dead. (Remember, these were all terminal cancer patients.) However, in the vitamin C group, half were still alive nearly a year later. The vitamin-C group had women with terminal breast cancer still alive 2,270 days later and counting.

The control groups for all the different cancers studied did predictably poorly, with the vast majority dead within 100 to 200 days, while the vitamin C-treated patients appeared to do substantially better. All in all, the average survival time was four times as great for the vitamin C subjects—more than 200 days compared to only 50 days for the control patients. The results, the researchers concluded, “clearly indicate that this simple and safe form of medication is of definite value in the treatment of patients with advanced cancer.” So, what happened after the study was published back in 1976?

Critics understandably attacked the study for using after-the-fact controls. One can see how this could introduce bias. If researchers consciously or unconsciously chose control group patients who were sicker than the treatment group patients, the control group patients would die sooner than the treatment group patients, but it would have nothing to do with the treatment; the control group folks may have just started out in a worse place. Indeed, there is evidence that is what happened: A full 20 percent of the control group died within a few days after being declared terminal compared to none in the treatment group, which really does seem fishy. Nevertheless, the trial was successful in finally convincing the National Cancer Institute to fund randomized controlled trials—performed by the prestigious Mayo Clinic, no less. What did they find? Find out in Vitamin C Supplements for Terminal Cancer Patients and The Role of Vitamin C in the Treatment of Terminal Cancer.


I have tons of videos on cancer, but here’s a sampling:

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: