Does Aspartame Cause Lymphoma?

The approval of aspartame has a controversial history. The Commissioner of the U.S. Food and Drug Administration (FDA) concluded that “there is a reasonable certainty that human consumption of aspartame: (1) …will not pose a risk of brain damage resulting in mental retardation, endocrine [hormonal] dysfunction, or both; and (2) will not cause brain tumors.” However, the FDA’s own Public Board of Inquiry withdrew their approval over cancer concerns. “Further, several FDA scientists advised against the approval of aspartame, citing…[the aspartame company’s] own brain tumor tests…” Regardless, the Commissioner approved aspartame before he left the FDA and went on to enjoy a thousand-dollar-a-day consultancy position with the aspartame company’s PR firm. Then, the FDA actually prevented the National Toxicology Program (NTP) from doing further cancer testing. As I discuss in my video Does Aspartame Cause Cancer? we were then left with people battling over different rodent studies, some of which showed increased cancer risk, while others didn’t.

This reminds me of the saccharin story. That artificial sweetener caused bladder cancer in rats but not mice, leaving us “to determine whether humans are like the rat or like the mouse.” Clearly, we had to put the aspartame question to the test in people, but the longest human safety study lasted only 18 weeks. We needed better human data.

Since the largest rat study highlighted lymphomas and leukemias, the NIH-AARP study tracked blood cancer diagnoses and found that “[h]igher levels of aspartame intake were not associated with the risk of…cancer.” Although the NIH-AARP study was massive, it was criticized for only evaluating relatively short-term exposure. Indeed, people were only studied for five years, which is certainly better than 18 weeks, but how about 18 years?

All eyes turned to Harvard, where researchers had started following the health and diets of medical professionals before aspartame had even entered the market. “In the most comprehensive long-term [population] study…to evaluate the association between aspartame intake and cancer risk in humans,” they found a “positive association between diet soda and total aspartame intake and risks of [non-Hodgkin’s lymphoma] and multiple myeloma in men and leukemia in both men and women,” as you can see at 2:12 in my video. Why more cancer in men than women? A similar result was found for pancreatic cancer and diet soda, but not soda in general. In fact, the only sugar tied to pancreatic cancer risk was the milk sugar, lactose. The male/female discrepancy could have simply been a statistical fluke, but the researchers decided to dig a little deeper.

Aspartame is broken down into methanol, which is turned into formaldehyde, “a documented human carcinogen,” by the enzyme alcohol dehydrogenase.The same enzyme that detoxifies regular alcohol is the very same enzyme that converts methanol to formaldehyde. Is it possible men just have higher levels of this enzyme than women? Yes, which is why women get higher blood alcohol levels than men drinking the same amount of alcohol. If you look at liver samples from men and women, you can see significantly greater enzyme activity in the men, so perhaps the higher conversion rates from aspartame to formaldehyde explain the increased cancer risk in men? How do we test this?

Ethanol—regular alcohol—competes with methanol for this same enzyme’s attention. In fact, regular alcohol is actually “used as an antidote for methanol poisoning.” So, if this formaldehyde theory is correct, men who don’t drink alcohol or drink very little may have higher formaldehyde conversion rates from aspartame. And, indeed, consistent with this line of reasoning, the men who drank the least amounts of alcohol appeared to have the greatest cancer risk from aspartame.

A third cohort study has since been published and found no increased lymphoma risk associated with diet soda during a ten-year follow-up period. So, no risk was detected in the 18-week study, the 5-year study, or the 10-year study—only in the 18-year study. What should we make of all this?

Some have called for a re-evaluation of the safety of aspartame. The horse is kind of out of the barn at this point with 34 million pounds of aspartame produced annually, but that doesn’t mean we have to eat it, especially, perhaps, pregnant women and children.


For more information on the effects of aspartame, watch my videos Aspartame and the Brain and Aspartame-Induced Fibromyalgia. Interested in learning more about the effects of consuming diet soda? See, for example:

What about Splenda? Or monk fruit sweetener? I have videos on those, too—watch Effect of Sucralose (Splenda) on the Microbiome and Is Monk Fruit Sweetener Safe?.

I also do a comparison of the most popular sweeteners on the market, including stevia and xylitol, in my video A Harmless Artificial Sweetener.

Perhaps the best candidate is erythritol, which you can learn about in my video Erythritol May Be a Sweet Antioxidant. That said, it’s probably better if we get away from all intense sweeteners, artificial or not. See my video Unsweetening the Diet for more on this.

In health,
Michael Greger, M.D.

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Fennel Seeds vs. Ginger for Menstrual Cramps and PMS

Ninety percent of women report having painful menstrual cramps at least some of the time. Around the Mediterranean, fennel seeds have been traditionally used to relieve painful menstruation. We call them seeds, but they’re actually whole little fruits. I discuss their effectiveness in the treatment of menstrual cramps in my video Fennel Seeds for Menstrual Cramps and PMS. It’s hard to create placebo seeds, so researchers used fennel seed extract to put it to the test. The women started out rating their pain as six out of ten, which then went down to a four within an hour after the taking the fennel seed extract. Fifty-two percent of the women rated the fennel seed treatment as excellent, compared with only 8 percent of those in the placebo group who were just unknowingly given placebo capsules just containing flour.

But women don’t take flour for cramps; they take drugs such as ibuprofen. Mefenamic acid is in the same class of nonsteroidal anti-inflammatory (NSAID) drugs and may actually work better than ibuprofen, but it is not available over the counter. How did it do against an extract of fennel seeds? In a head-to-head study, most women started out in severe pain but ended up pain-free after treatment, and the fennel worked just as well as the drug class considered the treatment of choice––but without the drug’s side effects, which include diarrhea, rashes, autoimmune anemia, and kidney toxicity.

The drug also doesn’t help with the other symptoms of bad periods. During menstruation, women can feel nauseated, out of sorts, weak, achy, and diarrheic. But when put to the test, fennel seeds seemed to help; however, the control group wasn’t given a placebo, so we don’t know how much of that was a placebo effect.

One downside of taking fennel is that women bleed about 10 percent more. Menstrual cramps are caused by the uterus contracting so hard its blood supply is compromised, and we think fennel works through muscle relaxation. It also helps with infant colic, which is thought to be due to intestinal spasms. The advantage of fennel there, too, is the lack of side effects, unlike the drug commonly used for colic. Indeed, dicyclomine hydrochloride can work a little too well to get your baby to stop crying––by developing side effects like death.

Ginger is effective for cramps and reduces bleeding when an eighth of a teaspoon of ginger powder is taken three times a day during one’s period. This is important since up to 18 million young women in the United States experience iron deficiency anemia due to heavy menstrual bleeding. In a study, the amount of blood loss was estimated using a scoring system that gave points for level of saturation and clot size. On ginger, they went from half a cup per period down to a quarter cup. Ginger appears to be a highly effective treatment for the reduction of menstrual blood loss. It is cheap, at only about 6 cents a month, easy to use, and may have fewer side effects than medications and invasive approaches, even sometimes fewer than placebo! The researchers used lactose (milk sugar) for the sugar pills, which may have caused the reported flatulence.

Ginger may also work better for premenstrual syndrome (PMS). An eighth of a teaspoon twice a day of ginger powder for a week before one’s period yields a significant drop in PMS mood, physical, and behavioral symptoms, whereas fennel may help with PMS anxiety and depression but not with the emotional or physical symptoms.


Other dietary interventions that may help include a reduction in salt and animal fat consumption, which I address in my video Dietary Treatment for Painful Menstrual Periods.

We should use whatever works––because sometimes, evidently, PMS symptoms can lead to death. Case in point: Christine English who, at that time of the month, ran down her husband. Accepting PMS as a defense, the court released her with one year of probation.

For more on treating menstrual pain and PMS, 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: