What’s the Best Ferritin Level to Lower Cancer Risk?

If cancer is indeed a so-called ferrotoxic disease, a consequence, in part, of iron toxicity, that would explain not only the dramatic drop in cancer rates after blood donations, but also why people with higher levels of iron in their blood have an increased risk of dying from cancer, why women who bleed into their ovaries are at high risk for ovarian cancer, and why those suffering from hemochromatosis (an iron overload disease) have up to 200 times the risk of cancer. There has even been a call to go back and look at some of the chemotherapy trials that kept taking blood from the chemo group to check for side effects. Perhaps just the iron removal from the blood draws accounted for some of the apparent chemo benefits.

Iron may be a double-edged sword, as I explore in my video Donating Blood to Prevent Cancer?. Iron deficiency causes anemia, whereas excessive iron may increase cancer risk, presumably by acting as a pro-oxidant and generating free radicals. Iron-deficiency anemia is a serious problem in the developing world. “In meat-eating countries, however, iron excess may be more of a problem than iron deficiency…Body iron stores accumulate insidiously with ageing due to the fact that intake exceeds loss,” and our body has no good way of getting rid of excess iron.

Ferritin is a blood test measure of our backup iron stores. As you can see at 1:31 in my video, the normal range is about 12 to 200 ng/mL—but just because it’s normal doesn’t mean it’s ideal. In the blood donor study discussed earlier, those who developed cancer had ferritin levels around 127.1 ng/mL. The average for men may be over a hundred.

This suggests that so-called normal, “ambient levels of iron stores may be noxious and constitute a ‘public’ problem that affects large segments of the population.” As such, “[t]here may be a need to redefine the normal range…based on associated disease risk” rather than following a bell curve. “Thus, iron deficiency may exist when ferritin levels decline to less than about 12 ng/mL, whereas ferrotoxic disease may occur with levels greater than about 50 ng/mL.”

Harvard recently looked at blood donations and colorectal cancer, and found no connection, but the range of ferritin levels the researchers looking at was roughly 100 to less than 200 ng/mL, as you can see at 2:28 in my video. What’s more, those were from individuals who reported giving blood 30 or more times. So, perhaps instead of draining our blood to reduce excess iron stores, why not prevent the iron overload in the first place? If we measure the iron stores of men who stay away from heme iron and, instead, get all of their iron from plants, their iron levels are right around where the cancer-free donor group came in, as you can see at 2:54 in my video. This may help explain why those eating plant-based diets tend to have less cancer and other diseases associated with iron overload. Indeed, they may also have less pre-diabetes, as well as have less diabetes.


For more on the blood donor study I discussed, see Donating Blood to Prevent Heart Disease?.

For more on diet and iron levels, see The Safety of Heme vs. Non-Heme Iron and Risk Associated with Iron Supplements.

Interested in other examples of normal lab values not being necessarily ideal? Check out:

Even though a plant-based diet may be preferable for personal disease risk, that doesn’t mean we shouldn’t all give blood. Join me in supporting the Red Cross.

In health,
Michael Greger, M.D.

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

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:

Plant versus Animal Iron

It is commonly thought that those who eat plant-based diets may be more prone to iron deficiency, but it turns out that they’re no more likely to suffer from iron deficiency anemia than anybody else. This may be because not only do those eating meat-free diets tend to get more fiber, magnesium, and vitamins like A, C, and E, but they also get more iron.

The iron found predominantly in plants is non-heme iron, which isn’t absorbed as well as the heme iron found in blood and muscle, but this may be a good thing. As seen in my video, The Safety of Heme vs. Non-Heme Iron, avoidance of heme iron may be one of the key elements of plant-based protection against metabolic syndrome, and may also be beneficial in lowering the risk from other chronic diseases such as heart disease.

The data linking coronary heart disease and the intake of iron, in general, has been mixed. This inconsistency of evidence may be because of where the iron comes from. The majority of total dietary iron is non-heme iron, coming mostly from plants. So, total iron intake is associated with lower heart disease risk, but iron intake from meat is associated with significantly higher risk for heart disease. This is thought to be because iron can act as a pro-oxidant, contributing to the development of atherosclerosis by oxidizing cholesterol with free radicals. The risk has been quantified as a 27% increase in coronary heart disease risk for every 1 milligram of heme iron consumed daily.

The same has been found for stroke risk. The studies on iron intake and stroke have had conflicting results, but that may be because they had never separated out heme iron from non-heme iron… until now. Researchers found that the intake of meat (heme) iron, but not plant (non-heme) iron, was associated with an increased risk of stroke.

The researchers also found that higher intake of heme iron—but not total or plant (non-heme) iron—was significantly associated with greater risk for type 2 diabetes. There may be a 16% increase in risk for type 2 diabetes for every 1 milligram of heme iron consumed daily.

The same has also been found for cancer, with up to 12% increased risk for every milligram of daily heme iron exposure. In fact, we can actually tell how much meat someone is eating by looking at their tumors. To characterize the mechanisms underlying meat-related lung cancer development, researchers asked lung cancer patients how much meat they ate and examined the gene expression patterns in their tumors. They identified a signature pattern of heme-related gene expression. Although they looked specifically at lung cancer, they expect these meat-related gene expression changes may occur in other cancers as well.

We do need to get enough iron, but only about 3% of premenopausal white women have iron deficiency anemia these days. However, the rates are worse in African and Mexican Americans. Taking into account our leading killers—heart disease, cancer, and diabetes—the healthiest source of iron appears to be non-heme iron, found naturally in abundance in whole grains, beans, split peas, chickpeas, lentils, dark green leafy vegetables, dried fruits, nuts, and seeds.

But how much money can be made on beans, though? The processed food industry came up with a blood-based crisp bread, made out of rye flour and blood from cattle and pigs, which is one of the most concentrated sources of heme iron, about two-thirds more than blood from chickens. If blood-based crackers don’t sound particularly appetizing, you can always snack on cow blood cookies. And there are always blood-filled biscuits, whose filling has been described as “a dark-colored, chocolate flavored paste with a very pleasant taste.” (It’s dark-colored because spray-dried pig blood can have a darkening effect on the food product’s color.) The worry is not the color or taste, it’s the heme iron, which, because of its potential cancer risk, is not considered safe to add to foods intended for the general population.

Previously, I’ve touched on the double-edged iron sword in Risk Associated With Iron Supplements and Phytates for the Prevention of Cancer. It may also help answer Why Was Heart Disease Rare in the Mediterranean?

Those eating plant-based diets get more of most nutrients since whole plant foods are so nutrient dense. See Nutrient-Dense Approach to Weight Management.

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: