People who eat nuts in their adolescence may have a better chance of fighting off breast cancer later in life, according to data from the Harvard Nurse's Study. A follow-up study involving the daughters of the nurses corroborated the findings. Those eating more peanut butter, nuts, beans, lentils, soybeans, or corn were found to have just a fraction of the risk for fibrocystic breast disease, which places one at higher risk of cancer. The protective effects were found to be strongest for those most at risk, such as those with a family history of breast cancer.
Another study out of the British Journal of Cancer found that even two handfuls of nuts a week may protect against pancreatic cancer, one of our most fatal malignancies.
Nuts are described as "nutritionally precious," which may explain some of the mechanisms by which nut components induce cancer cell death and inhibit cancer growth and spread in vitro. But which nuts work the best? In my video #1 Anticancer Vegetable, we learned that two classes of vegetables--the broccoli family vegetables and the garlic family vegetables--most effectively suppressed breast cancer cell growth. In Which Fruit Fights Cancer Better?, cranberries and lemons took the title.
What about nuts? In terms of antioxidant content, walnuts and pecans steal the show. Twenty-five walnuts have the antioxidant equivalent of eight grams of vitamin C (the vitamin C found in a hundred oranges).
But how do they do against cancer? In the video, Which Nut Fights Cancer Better?, you can see a graph of human cancer cell proliferation versus increasing concentrations of the ten most common nuts eaten in the United States. If you drip water on these cancer cells as a control, nothing happens. Hazelnuts, pistachios and Brazil nuts don't do much better. Pine nuts, cashews and macadamias start pulling away from the pack. Almonds appear twice as protective, halving cancer cell growth at only half the dose as pine nuts, cashews, and macadamias. Walnuts, pecans, and peanuts come out as the clear winners, causing a dramatic drop in cancer proliferation at just tiny doses.
- Fighting Inflammation in a Nut Shell
- Tree Nuts or Peanuts for Breast Cancer Prevention?
- How Do Nuts Prevent Sudden Cardiac Death?
- Nuts and Bolts of Cholesterol Lowering
- Nuts and Obesity: The Weight of Evidence
- Nuts May Help Prevent Death
- Walnuts and Artery Function
- Four Nuts Once a Month
-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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.
Image Credit: Mariya Chorna / Flickr
Doctors appear to be causing tens of thousands of cancers with CT scans and dentists may be causing a few brain tumors with dental X-rays (see my two videos Cancer Risk from CT Scan Radiation and Do Dental X-Rays Cause Brain Tumors?), but what about these new-fangled airport full-body scanners that use so-called backscatter technology to reduce X-ray exposure? A thousand times less radiation exposure than a chest X-ray, though they’re still being phased out. In fact, flight passengers may get 100 times more radiation during the flight every hour, because they’re so high up in the atmosphere and exposed to more cosmic rays. Does that mean a round-trip cross-country flight is almost like getting a chest X-ray? Yes. Anyone who’s seen my speaking schedule knows I’m totally screwed. But what can you do? As is the answer to so many health questions, you can eat healthily.
High dietary antioxidant intakes are associated with decreased DNA damage in airline pilots. Note the word “dietary.” Antioxidant supplements didn’t work. No benefit was found for those taking multivitamins, vitamin C pills, or vitamin E pills. But those getting the most vitamin C from food, B carotene from food, cryptoxanthin from food, and lutein/zeaxanthin from food, saw a significant decrease in DNA damage.
The USDA keeps a nice list of phytonutrient resources. Cryptoxanthin sources listed here (Healthy Pumpkin Pie anyone?). Lutein and zeaxanthin can help us Prevent Glaucoma and See 27 Miles Farther and may present a Dietary Prevention of Age-Related Macular Degeneration. Are these eyesight-saving phytonutrients also found in eggs? You might be surprised. See Egg Industry Blind Spot.
For more on why produce is generally preferable to pills, check out:
- Can Folic Acid Be Harmful?
- Lutein, Lycopene, and Selenium Pills
- Produce, Not Pills to Increase Physical Attractiveness
- Risk Associated With Iron Supplements
- Some Dietary Supplements May Be More Than a Waste of Money
- Update on Juice Plus+®
- Update on Vitamin E
These are all phytonutrients, of course, so when they say food, they really mean plants. And because antioxidants can have synergistic effects, the greatest protection was found when they were eating a combination of phytonutrients, so the greatest protection was found in those eating the citrus and broccoli and nuts and seeds and pumpkins and peppers and dark green leafy vegetables. Though if one had to pick, greens may be the best. All this time I’ve been packing kale chips on planes as a snack just because they’re so lightweight, but now I know their dual purpose.
The researchers conclude that a diet consisting of a variety of fruits and vegetables provides a natural source of these antioxidants as well as other potential protective factors, which may offer the best protection against cumulative DNA damage associated with ionizing radiation exposure. The results are especially relevant to flight crews, astronauts, and frequent flyers.
The same thing was found following Hiroshima and Nagasaki atomic bomb survivors for decades. Models based on the available data suggest that the cancer risk in exposed persons may have been knocked down by daily green and yellow vegetable consumption from about 50% increased cancer risk to only about 30% increased risk. Similar results were found for fruit consumption. So fruit and vegetable consumption can diminish, but not eliminate the risks of radiation.
Same thing was found following children after Chernobyl. I profile a study in my video Mediating Radiation Exposure From Airline Travel in which consumption of fresh vegetables and fruits was found to afford protection to the immune systems of exposed children, whereas egg and fish consumption was associated with significantly increased risk of chromosome damage within their bodies. Researchers were unsure whether the damage attributed to fish and eggs was because the eggs and fish carried radioactivity, or whether it was just from the animal fat intake alone.
Why might eggs be harmful even if not radioactive? See Who Says Eggs Aren’t Healthy or Safe? or my other 58 videos on eggs. I cover natural and artificial radioactivity in fish in Fukushima and Radioactivity in Seafood and explore concerns about other pollutants in my 89 fish videos.
For interventional studies where plant foods are actually put to the test, see Reducing Radiation Damage With Ginger And Lemon Balm.
-Michael Greger, M.D.
Image credit: Sergé / Flickr
In the same way fermented pickles, kimchi, and sauerkraut foster the growth of good bacteria by maintaining an acidic environment, so does the human vagina. The normal pH of one’s vagina is that of tomato juice. However, once it starts creeping up to that of coffee, an overgrowth of bad bacteria can take hold and cause bacterial vaginosis, which affects an astounding 29 percent of American women, nearly 1 in 3. That makes it the most frequent cause of vaginal complaints among younger women. It’s commonly diagnosed with the so-called "Whiff Test," where the doctor takes a whiff of the vaginal discharge, sniffing for the characteristic fishy odor.
The fishy odor is a consequence of a compound of decay called putrescine, which is also found in certain foods. More about these “biogenic amines” in:
Traditional risk factors for bacterial vaginosis include douching, which has also been associated with a wide range of problems. With no demonstrable benefits and considerable evidence of harm, douching should be strongly discouraged. Medical professionals need to clearly explain to women that the vagina is naturally self-cleaning.
Nasal douching, though, is another matter entirely. See The Risks and Benefits of Neti Pot Nasal Irrigation and my answer about the “brain-eating amoeba.”
Recently, poor nutrition has been added to the list of risk factors for bacterial vaginosis. Women appear more likely to get bacterial vaginosis if they have lower circulating levels of phytonutrients like vitamin C and beta carotene in your bloodstream—indicating a lower intake of fruits and vegetables. In recent years, though, the field of nutrition has shifted toward examining overall dietary scores as opposed to single nutrients, because it has become recognized that nutrients are not consumed in isolation. To help consumers eat healthier foods, nutrient-rich food indices have been devised. Using these indices, researchers have found that the more nutrient rich one’s diet, the lower one’s apparent risk for bacterial vaginosis.
Why might a healthier diet improve vaginal health? Researchers suggest that high fat intake, particularly saturated fat may increase vaginal pH, thereby increasing the risk of bacterial vaginosis. As you can see in the associated video Bacterial Vaginosis and Diet, most saturated fat in the American diet comes from dairy, desserts, and chicken. The researchers conclude: “The next steps ahead include sharing these findings with gynecologists, obstetricians, and general practitioners, as well as increasing the awareness of the general community to the importance of optimal nutrition… to prevent infections of the genital tract, reduce associated disease, and maintain reproductive health.”
More on the detrimental effects of saturated fat in videos such as:
- Beauty Is More Than Skin Deep
- Dead Meat Bacteria Endotoxemia
- Saturated Fat & Cancer Progression
- Breast Cancer Survival, Butterfat, and Chicken
- How to Help Prevent Abdominal Aortic Aneurysms
- Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero
What about male reproductive health? See Male Fertility and Diet.
-Michael Greger, M.D.
Image credit: Centers for Disease Control and Prevention / Flickr
More berried treasure! A story similar to the strawberries and esophageal cancer revelation I documented in Strawberries versus Esophageal Cancer has emerged with black raspberries and oral cancer.
Oral cancer is one of the 10 most common cancers in the US with a flip-of-the-coin death rate. We can reduce our risk of oral cancer by avoiding all forms of tobacco, restricting alcohol consumption, avoiding obesity, and eating at least five servings of vegetables and fruits each day. Other risk factors include having more than 5 lifetime oral sex partners and prolonged (more than 20 years) marijuana use. But what if we already have precancerous changes in your mouth?
Black raspberries appear to selectively inhibit the growth of both malignant and premalignant cells in a petri dish while leaving normal cells alone, but what about in an actual person? Researchers at Ohio State University took some folks with precancerous growths in their mouths (so called oral “intraepithelial neoplasia”) and had them apply a black raspberry gel for 6 weeks.
Like the esophageal study with strawberries, most of the patients’ lesions improved, including cases of complete clinical regression. If you click to watch my 4-min video Black Raspberries versus Oral Cancer you can see the disease disappear–thanks to just berries! They were able to follow a reversal of genetic changes that had led to the silencing of tumor suppressor genes.
If you aren’t near a pick-your-own farm, black raspberries can be ordered online frozen but they’re about 20 bucks a pound with shipping. Black raspberry freeze-dried powder is comparatively cheaper, but I’ve always wondered about how much nutrition is lost. Well, there’s finally been a study.
The antioxidant concentration was measured in fresh, frozen, and freeze-dried strawberries and strawberry jam, with the intent of measuring antioxidant content of foods typically available to consumers in grocery stores. On a consumed weight basis, the freeze-dried do shine, but just because an ounce of dried is equivalent to about a cup and a half of fresh. Jam, though, presumably because of the heat processing, really takes a hit (chart in my video Black Raspberries versus Oral Cancer).
I’ve previously covered the clinical trials of black raspberries (though in a different orifice) in Best Fruits For Cancer Prevention. I also touched on the adverse effects of breathing smoke from any source in Cannabis Receptors & Food.
Berries in general are the healthiest fruits and I encourage everyone to try to fit them into their daily diet. Here are a few of my 37 other videos on berries:
- A Better Breakfast
- Amla Versus Cancer Cell Growth
- Better Than Goji Berries
- Bulking Up on Antioxidants
- Clinical Studies on Acai Berries
- Cranberries versus Cancer
- Dietary Guidelines: From Dairies to Berries
- Improving Memory Through Diet
- Tart Cherries for Insomnia
- Treating COPD With Diet
- Which Fruit Fights Cancer Better?
-Michael Greger, M.D.
Image credit: Maggie Hoffman / Flickr
When measured on a cost per serving, cost per weight, or cost per nutrition basis, fruits and vegetables beat out meat and junk food:
Most Americans don’t even meet the watered down Federal dietary recommendations. Some have suggested this is because healthy foods are more expensive, but is that true? It depends on how you measure the price.
For over a century the value of food has been measured cost per calorie. If you were a brickmaker in Massachusetts in 1894, you may have needed more than 8000 calories a day. The emphasis was therefore on cheap calories. So while beans and sugar both cost the same back then--5 cents a pound--table sugar beat out beans for fuel value.
Of course food offers much more than just calories, but they can be excused for their ignorance, since vitamins and minerals hadn’t even been discovered yet. Even to this day, though, when the cost of foods are related to their nutritive value, the value they’re talking about is cheap calories. When you rank foods like that, then indeed junk food and meat is cheaper per calorie than fruits and vegetables, but that doesn’t take serving size into account. If you measure foods in cost per serving or cost per pound fruits and vegetables are actually cheaper (see the graphs in my 3-min video Eating Healthy on a Budget). For all metrics except the price of food calories, the USDA researchers found that healthy foods cost less than less healthy foods.
Most importantly, though, which is going to have the most nutrition? In the graphs in Eating Healthy on a Budget I show the average nutrient density of fruits, vegetables, refined grains, meats, milk, and empty calorie foods. Turns out that while junk food may be 4 times cheaper than vegetables, there’s 20 times less nutrition. For meat, we’d be spending 3 times more to get 16 times less.
Conclusion: “Educational messages focusing on a complete diet should consider the role of food costs and provide specific recommendations for increasing nutrient-dense foods by replacing some of the meat with lower-cost nutrient-dense foods…Modifying traditional mixed dishes to incorporate more beans/legumes and less meat may be a cost-effective way to improve diet quality.” That’s good advice for everyone, not just low-income populations.
In my video, Eating Healthy on a Budget, I also show what 100 calories of cheese, candy, chicken, chips, bread, oil, fruits or vegetables looks like. Which hundred calories do you think would fill you up more? I explore the calorie density of other foods in my video Diet vs. Exercise for Weight Loss.
I have some other videos along the same vein:
- Eating Healthy on the Cheap
- Biggest Nutrition Bang for Your Buck
- Cheapest Source of Vitamin B12
- The Effect of Canned Tuna on Future Wages
- Are Goji Berries Good for You?
- Superfood Bargains
Hasn’t the nutrition of our crops declined over the decades though? Or is that just supplement manufacturer propaganda? Find out in my video Crop Nutrient Decline. And if you want to strive to maximize the nutrient density of your diet, check out Calculate Your Healthy Eating Score.
-Michael Greger, M.D.
Just a teaspoon of ground flaxseeds a day may help protect against breast cancer.
In 1980 a new compound was discovered in human urine. Researchers called it "compound X." Originally it was thought to be a new human hormone, but it was soon identified as part of a large group of fiber-associated compounds widely distributed in edible plants known as lignans. Vegetarians have about twice the level of lignans circulating within their bodies given their greater intake of plant foods. Since population studies suggested that high intake of lignans reduces breast cancer risk, perhaps lignans are one of the reasons those eating plant-based diets have lower cancer rates.
Where are lignans found most in the diet? Seeds, whole grains, vegetables, fruits and berries. Since these are all really healthy foods in their own right, maybe lignan intake is just acting as a surrogate marker for whole plant food intake? (Like the fiber story I detail in Fiber vs. Breast Cancer). Well, in a petri dish lignans do directly suppress the proliferation of breast cancer cells but only after the plant lignans are converted into human lignans by the bacteria in our gut. (More detail in Flax and Fecal Flora).
That’s why we want to use antibiotics judiciously. A few days on antibiotics dramatically drops our body’s ability to make these anticancer compounds from the plants that we eat, and it can take weeks for our gut bacteria to recover. That may be why women with urinary tract infections have been found to be at higher risk for breast cancer. Every time they took a course of antibiotics they may have been stymying their good bacteria’s ability to take full advantage of all the plants they were eating.
In my 4-min video Flaxseeds & Breast Cancer Prevention I profile the National Cancer Institute study that provides the strongest evidence to date that there might indeed be something special about this class of phytonutrients for breast cancer prevention. They took a bunch of young women at high risk for breast cancer (meaning they had a suspicious breast biopsy showing either atypical hyperplasia or carcinoma in situ, or already had breast cancer in the other breast) and gave them a teaspoon of ground flaxseeds every day for a year before getting a repeat needle biopsy to see if there was any change.
Yes, there are lignans in sesame seeds, nuts, whole grains, legumes, certain fruits, and veggies, but they’re most concentrated in flax seeds. They could have instead asked women to eat ten cups of strawberries a day for a year to get teh equivalent amount, but they’d probably get better compliance with just a teaspoon of flax :)
So what happened by the end of the year? The primary end point was the expression of a proliferation biomarker associated with cancer called ki-67. In 9 of the 45 women it went up, pictured in red in the video, but in the other 80% of the women it went down. And, indeed, on average they found less cellular proliferation in their breast tissue and fewer precancerous changes.
For those that don’t like the taste of flaxseeds, sesame seeds are also high in lignans. Even though flaxseeds have significantly more lignans than sesame, you appear to produce about the same amount of lignans from them. This was, however, comparing them whole. When people are fed whole flaxseeds, some may not be chewed up and can pass right through you. So ground flaxseed may be best overall. As I note in the Flaxseeds For Sensitive Skin video, ground flax stays fresh even at room temperature for at least a month.
What if you or a loved one has already been diagnosed with breast cancer? See my follow-up videos:
- Flaxseeds & Breast Cancer Survival: Epidemiological Evidence
- Flaxseeds & Breast Cancer Survival: Clinical Evidence.
-Michael Greger, M.D.
Image credit: kickthebeat / Flickr