Friday, December 10, 2010

Should we swap aspirin for vegetables? Not just yet.

Two cancer studies grabbed the headlines this week, causing nutritionists' hearts to sink and pharmacists to cheer. One suggested that vegetables and fruits offer scant protection against cancer; the other indicated that taking low daily doses of aspirin may cut our risk of dying of this dreaded disease. So, should we simply give up on vegetables and fruits, and pop the little white pill instead? I think not.

In the first article published in the British Journal of Cancer, Oxford University Professor Tim Key summarized evidence from several dozen long-term research projects looking at the amount of fruit and vegetables people eat and their overall cancer risk. He found little, if any, connection between eating lots of fruits and vegetables and the likelihood of developing cancer.

Meanwhile, the Lancet published a study showing that people who took a low dose of aspirin daily to lower their risk of cardiovascular disease were 20% less likely after 20 years to die of solid tumor cancers than those who had been taking placebo pills during the clinical trials, and their risk of gastrointestinal cancer death was 35% lower. The risk of lung cancer death was 30% lower, that of colorectal cancer death was 40% lower and that of esophageal cancer death was 60% lower.

The inflammation connection

Aspirin is thought to act on cancer through its ability to reduce inflammation, which plays a role in the development and spread of cancer cells. In animal studies, aspirin has been shown to block the synthesis of prostaglandins, chemicals that mediate inflammation and promote early tumors.

Whether aspirin systematically protects humans from cancer is uncertain, however. Indeed, the study notes that the results of observational studies in humans "have been conflicting, with more rigorous studies yielding weaker associations." Since few women took part in the trials studied, it is also unknown whether aspirin protects against breast or uterine cancer.

What we do know is that prolonged aspirin use can have negative side-effects, including gastrointestinal bleeding and bleeding in the brain. Non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin can also disrupt the gut flora and increase intestinal permeability, thereby in fact increasing the body's inflammatory burden. (See this paper, this and this). So don't start a regimen of aspirin without first weighing up the potential benefits and risks of such a treatment with a doctor.

Those who can't or won't take a daily dose of aspirin may wish to turn their attention to ways in which food can be used to regulate inflammation. Many of those much-maligned vegetables and fruits, as well as spices, herbs and fats with a healthy omega-3-to-6 ratio, are thought to help cool inflammation, as well as providing antioxidants and a plethora of other compounds that work in different ways to protect the body against cancer.

Alas, these foods are woefully lacking in our western convenience-food diets, which are characterized by inflammation-promoting sugar and refined carbohydrates, trans fats in processed foods, oils with a high proportion of omega-6 fatty acids (e.g. corn, soy, safflower) and meat, eggs and milk from intensively-reared animals fed corn, rather than grass and hay.These should be replaced by foods that can reduce inflammation, such as:
  • Vegetables like peppers, broccoli and broccoli sprouts, Brussels sprouts, cabbage, cauliflower, chard, collards, fennel, garlic, onions, kale, leeks, spinach, sweet potatoes
  • Fruits such as acerola cherries, apples, avocados, black currants, blueberries, kiwifruit, lemons, limes, mulberries, oranges, raspberries and strawberries
  • Herbs and spices like ginger, turmeric, curry mix, basil, cayenne and chili peppers, cinnamon, cloves, cocoa, mint, oregano, parsley, rosemary and thyme
  • Nuts and seeds containing healthy fats, like olives, almonds, flaxseed, hazelnuts and walnuts (olive oil has been found to contain a compound called oleocanthal that acts similarly to the NSAID ibuprofen)
  • Oily fish, such as sardines, mackerel, herring, anchovies and wild salmon which are rich in soothing omega-3 fats, and a healthy omega-3-to-6 ratio in the overall diet
In addition to containing natural anti-inflammatory compounds, vegetables and fruits do act in some indirect and hard-to-measure ways on cancer risk.

"People who eat a large proportion of fruit and vegetables are less likely to be overweight or obese, which is a major cancer risk factor," notes Dr Rachel Thompson, deputy head of science at the World Cancer Research Fund. Most fruits and vegetables are low in calories and contain fiber which helps to make us feel full and hence stops us eating too much and gaining weight, she explains. The World Cancer Research Fund has issued a list of ten recommendations to reduce cancer risk.

Even cigarette smokers, the most at-risk from cancer, are protected if they eat vegetables and fruits. A recent study (which I wrote about here) showed smokers who ate the greatest variety of fruits and vegetables were 27% less likely to get squamous cell lung cancer than those with the least variety. (Of course, not smoking at all confers much greater protection!)

So before you rush to the drug store to stock up on aspirin, may I suggest you head into the kitchen and cook yourself a nice vegetable-and-fish curry. I made one last night that contained red onions, leeks, carrots, broccoli, mushrooms and salmon, swimming in a coconut-milk sauce spiced with turmeric, ginger, garlic, ground coriander, pepper and chili flakes. It was warming, quick and easy to prepare.

Wednesday, November 24, 2010

Amazing Grace: The digestive and emotional benefits of mealtime grace

When our eldest son was five, we started to say grace at mealtime. Untrained in matters of gastronomic spirituality, we began by rolling a wooden cube inscribed with six child-friendly, non-denominational prayers: whichever verse landed face-up was recited.

Soon we got bored of rattling off the same six prayers and decided to wing it. Now we no longer call it grace and we don't couch it in religious terms (though the children like to finish with a rousing 'Amen!' every now and then), but we find it hard to begin a meal without a brief moment of calm.

Grace and gratitude are closely related (the Latin gratia means 'good will' or 'gratitude'). At home, we now refer to mealtime grace as the 'Thankfulness Moment.' Much like a Thanksgiving dinner, every person at the table expresses his or her gratitude for something.

When we are eating meat or fish, for instance, our 8-year-old son always thanks the animal for giving its life for us. His twin sister often gives thanks for family and friends. Our teenage son is often grateful for the fact that we are all together at the table, or that it's Friday. My husband and I give thanks for children, health and a comfortable home.

When children are jittery or parents tired, we sometimes hold a 'silent grace' where we link hands and sit quietly for as long as the children can bear (about one or two minutes). A note of caution: when young children are present, make sure you keep your food warm during grace; their thanksgiving can go on for quite a while as they express gratitude for teachers, friends, the weather, pets, a snuggly pyjama or a favourite soft toy.

Mealtime grace doesn't have to be a religious act. If for no other reason, saying grace - some would prefer to call it 'meditating/relaxing before a meal' - is worth adopting because it has a strong bearing on nutritional health. For as we settle for the moment of calm that precedes the meal, our body relaxes and our organs prepare to digest and absorb the food we are about to eat.

At the thought, sight and smell of food, gastric juices start flowing, enzymes are secreted, and the body stops whatever it is doing to relax and welcome the incoming nourishment. Our in-built fight-or-flight stress response, which dates back to our hunter-gatherer days and which halts digestive processes at times of stress, is suspended, making way for digestion and absorption.

Indeed, scientists have found that eating in a relaxed state may be even more healthful than chewing one's food thoroughly! In one study, subjects who ate complex carbohydrates under stressful conditions secreted less of the carbohydrate-digesting enzyme amylase than those eating under relaxed conditions. The study's authors conclude that "deep relaxation was significantly more important than thorough chewing in the oral digestion of complex carbohydrates." Stress has also been shown to cause trouble further down the digestive tract, disrupting the gut flora and contributing to the development of food allergies (see this study).

Grace doesn't just boost your digestive system though. In recent years, psychologists have turned their attention to the study of gratitude, and not surprisingly, they have found that our ability to experience and express gratitude is a key determinant of our overall health and happiness.

"Gratitude leads people to act in virtuous or more selfless ways," according to Northeastern University psychologist David de Steno. "And it builds social support, which we know is tied to both physical and psychological well being."

But there's a catch: gratitude only ‘works' if you express it on a regular basis. "If you don't do it regularly you're not going to get the benefits," notes Sonja Lyubomirsky, a psychology professor at the University of California, Riverside. "It's kind of like if you went to the gym once a year. What would be the good of that?"

According to Robert Emmons, a psychology professor at the University of California, Davis, people who express gratitude are less resentful, experience longer and better-quality sleep, exercise more and report a drop in blood pressure. "The practice of gratitude can increase happiness levels by around 25%," he estimates.

For many people I know, the past few years have been difficult. Some have experienced economic hardship and employment worries, others have endured ill health and troubled personal relationships.

When life is tough, it's hard to feel grateful. But it's precisely when we feel down that it may be most helpful to tap into feelings of gratitude. When I sit down and focus on things to be grateful for (people who are more organised than me keep a 'gratitude diary,' something I may start in the New Year...), I usually begin by being thankful for small blessings: the purring of the cat on my lap or the comforting warmth of my sweater.

This quickly brings me to big blessings: the food on my table, the chatter of my children, my husband who shares my burdens, hopes and dreams, friends who will listen on the phone or over a cup of tea. As I consider these gifts, I feel suffused by a warm glow of gratitude, and feelings of sadness, hurt and anger recede.

For this is the beauty of gratitude: you can't be simultaneously angry and grateful, or depressed and grateful, or selfish and grateful. Gratitude is the most potent counterforce to egoism, ruthlessness, greed and the many other masks behind which unhappiness hides. By forcing ourselves to experience, and to express, gratitude -- if only once a day, at mealtimes -- we can rise above the darker side of human nature.

So why can't we all show a little more gratitude? According Emmons, "some people feel uncomfortable talking about these topics, since they may sound too spiritual, or religious. Others simply don't want to feel obligated to the person who helped them, and never come to realize the boost in energy, enthusiasm, and social benefits that come from a more grateful, connected life."

Here's wishing you a Thanksgiving filled with light, peace and a healthy digestion!

Friday, November 19, 2010

Mediterranean diet gets UNESCO's stamp of approval

Increasingly under threat from mass-produced fast-food, the Mediterranean diet received a boost this week when the United Nations' culture and education agency UNESCO added it to its list of cultural heritage worth preserving and promoting.

A press release issued after the meeting of UNESCO's Intergovernmental Committee for the Safeguarding of the Intangible Cultural Heritage highlights the Mediterranean diet's widely-accepted healthfulness. But to me, at least as important is the agency's emphasis on the socio-cultural elements of the Mediterranean diet.

"The Mediterranean diet (from the Greek diaita, or way of life) encompasses more than just food. It promotes social interaction, since communal meals are the cornerstone of social customs and festive events. It has given rise to a considerable body of knowledge, songs, maxims, tales and legends. The system is rooted in respect for the territory and biodiversity, and ensures the conservation and development of traditional activities and crafts linked to fishing."

The UNESCO also notes that women play "a particularly vital role in the transmission of expertise, as well as knowledge of rituals, traditional gestures and celebrations, and the safeguarding of techniques."

This is an interesting point, for one reason why home-cooked family meals are in decline in the Mediterranean region is the increased number of women who work outside the home. (See this article about the sharp rise in obesity around the Mediterranean following the marked shift in nutritional habits and demographic trends.) Of course I do not 'blame women' for abandoning home-cooking; I blame social structures that make it very difficult for women and men to both work and prepare healthy, natural food for their families.

The request for recognition of the diet was made by the governments of Italy, Spain, Greece and Morocco. Each of these countries is now committed to undertaking a series of safeguarding efforts, together with a plan for transnational measures aimed at ensuring transmission to younger generations and promoting awareness of the Mediterranean diet.

Some commentators have dismissed the Mediterranean diet's inclusion on the UNESCO's heritage list as PR gimmickry, or, more cynically still, as part of a marketing ploy to boost Mediterranean olive-oil sales. Citing varied cuisines around the Mediterranean basin, they also claim that there is no such thing as a distinct 'Mediterranean diet' and therefore no cultural heritage to preserve.

These cynics are missing the point. Cuisines vary around the Mediteranean because of the different climatic, geological, historical and cultural environments that shaped them. Yet, despite superficial differences, there is more that unites than divides them. For the traditional pre-industrial diets eaten in the whole region were, almost without exception, characterised by a high intake of vegetables, fruits, pulses, whole grains, nuts, seeds, herbs and spices, a moderate intake of fish, dairy and meat and accompanied by red wine (religious practices permitting).

Incidentally, anyone who is familiar with Mediterranean cuisines knows that many countries have similar dishes that go by different names: for example, Italy's pesto is virtually the same as the pistou of French Provence, which closely resembles the romesco sauce of Spain's Catalunya region or north African chermoula.

Meanwhile, to those who accuse the olive oil growers of dark and scheming motives, I say: the Mediterranean diet is precious precisely because, apart from olive oil and perhaps red wine, it is largely anti-commercial, being based on unprocessed, fresh food that offers slim profit margins to producers. It is the exact antithesis of the sort of diet the industrial food giants would have us eat, one that consists almost entirely of processed and denatured 'food-like edible substances' that are making us sick and fat.

Indeed, if everyone started eating a Mediterranean diet - fresh fruit and vegetables from farmers' markets, homemade whole-grain bread, eggs from chickens scratching in the back yard, meat and milk from animals raised on nearby meadows, etc. - the industrial food giants would soon be out of business.

Luckily for them, this isn't going to happen anytime soon, because, among others, many people below the age of 30 don't know how to produce or prepare food from scratch, nor do they remember the taste of fresh, natural, unadulterated food. Long working hours, competitive labor markets, uninspired school and workplace cafeterias and the ever-present lure of tasty but unnutritious convenience fare will ensure that young palates remain undemanding, even to the point of preferring a factory-made poultry nugget to a home-roasted chicken!

So while putting the Mediterranean diet on a list of threatened lifestyles is probably not enough to restore an ailing food culture, I think every effort is worth undertaking it if it means raising public awareness just that teeny little bit. Call me a hopeless romantic, but I believe that if more people ate a Mediterranean diet and enjoyed the life-affirming lifestyle that goes with it, the world could be a healthier and happier place.

Monday, November 15, 2010

Humble fruits that pack a powerful punch

For too long, plums, and especially their dried incarnations, prunes, have gotten a bum rap. This is mostly because of their unfortunate association with constipation, which they relieve quickly and naturally thanks to their high fiber content.

However, as we feast on this year's crop of this delicious stone fruit, it's time to stop snickering and start appreciating this humble stone fruit's many other health benefits. For in addition to their laxative qualities, plums, and their cousins, peaches and nectarines, appear to have cancer-fighting properties.

Animal and test-tube experiments have yielded promising results. Most recently, scientists at Texas A&M University discovered that breast cancer cells died after being treated with peach and plum extracts. The researchers treated healthy cells and breast cancer cells (including an aggressive non-hormone-dependent strain) with extracts from yellow-fleshed ‘Rich Lady' peaches and red-fleshed ‘Black Splendor' plums - both commercially available varieties.

"These extracts killed the cancer cells but not the normal cells," reports Luis Cisneros-Zevallos, Food Scientist and Associate Professor at Texas A&M University. "Our studies in vitro show the potential for selective killing of cancer cells, and our studies with mice have confirmed that these compounds inhibit metastasis," he adds. (Metastasis is the spread of cancer cells to other parts of the body.) Indeed, the effect of the fruit extract was strongest on the aggressive, non-hormone dependent cancer cells that most commonly metastasize, he notes. The research was published in the Journal of Agricultural and Food Chemistry.

What makes plums and prunes (coyly renamed ‘dried plums' by American prune marketers wishing to shake the stigma of geriatric constipation...) even more appealing is their low glycemic index (GI) ranking. (Anything below 55 is considered low.) According to the University of Sydney's Glycemic Index Database, prunes have a GI of 29, even below low-GI apricots (around 31) and half that of raisins (between 54 and 66). Foods with a high GI-value are thought to contribute to weight gain - a cancer risk factor - and the secretion of hormones such as insulin that can fuel cancer-cell growth.

Also in their favour, plums, prunes and peaches (ideally organically grown, to avoid pesticides: peaches and nectarines have among the hesviest pesticide residues, according to the Environmental Working Group's Shopper's Guide to Pesticides; plums fare better) are less expensive than many other fruits - especially imported tropical fruits or exiotic 'miracle foods' such as goji berries and acai fruit. This makes it easy to eat them on a daily basis, even for people with a tight food budget.

So what's the healthiest way to enjoy stone fruits? Straight off the tree. That's because phenolic compounds may be lost during processing, especially when subjected to heat, as in high-temperature canning and pasteurization for juice.

Alas, the plum season is short, so what can we do to get year-long protection from plum and peach compounds? Dried fruit is an option, as drying preserves a larger proportion of phenols than canning. "How much is lost will depend on the conditions of processing being used including temperature, air humidity and processing time," says Dr Cisneros-Zevallos. If you have a dehydrator, you may wish to experiment with fresh peaches and plums. Another option is frozen fruit - either bought fresh, pitted and frozen yourself, or bought ready-frozen.

Prune puree - which some call ‘prune butter' because of its thick, shiny texture - is quick and easy to make at home. Simply empty a packet of soft dried prunes into a bowl (making sure there's no stray pits left in any of them), pour warm water over them and leave to soak for an hour (or longer if they are very dry). Puree in a kitchen blender (you can add ginger or cinnamon for extra flavor) and transfer to a tightly sealed jar. This should keep for 3-4 weeks in the refrigerator.

In my house, we spread prune butter on toast, pancakes and waffles, mix it with plain yogurt and porridge or add it into fruit smoothies. We even serve it alongside roast meat (especially duck) as a sort of relish or chutney (adding a little salt, pepper and other spices). Lastly, one of my favorite recipes in Zest for Life is a chocolate-hazelnut spread that contains prune puree and tastes a lot like Nutella.

One excellent use of prune butter - which you can also buy in jars - is as fat replacement in baking. According to researchers at New York's Hunter College, pureed prunes can replace as much as 30 per cent of the fat by weight in chocolate cupcakes. The American Institute for Cancer Research's ‘Healthy Substitutions' page suggests replacing ½ cup of butter with ¼ cup prune purée and ¼ cup butter. As prune puree is dark and has a distinct flavor, this works best in spicy fruit cakes or chocolate cake (for example, Martha Stewart's ‘guilt-free' brownies - though I would reduce sugar content slightly and use whole grain flour). You can find dozens of other delicious prune recipes on the website of the California Dried Plums website.

Tuesday, October 19, 2010

Try it now: The Sit-Down Diet

Do you want to know about a diet that requires neither calorie-counting nor deprivation and doesn't involve weight-loss books, punishing exercise routines or expensive supplements? It's free, it's simple and anyone can do it. In fact, there's only one simple rule to follow: you may only eat when you are sitting down. Not in a car, not at a desk or in a subway train, but at a table designed for eating. I think I'll call it the Sit-Down Diet.

The idea was born from a passing comment my husband made last weekend when he saw me standing in the kitchen, eating leftovers off our children's plates before loading them in the dishwasher. "Have you noticed how often you eat standing up?" he observed, grinning. "I wonder what would happen if you only ever ate when sitting at the dining table." Thud went the gauntlet.

The Sit-Down Diet is based on the idea that when we sit down to eat, we consume fewer calories and more nutritious food than when we're standing up or walking. As an added bonus, when we sit down to eat and chew our food properly, we're more likely to digest and assimilate it well than when eating while rushing around.

Like most diets, the Sit-Down Diet may not work for everyone. But if, like me, you have a busy life and regularly snack on tasty tidbits while standing in front of your fridge, shopping, preparing a meal or travelling, it may work for you! And while the Sit-Down Diet is not (yet) scientifically proven, it is based on hard evidence.

For one, mindless eating is fattening. As Cornell University consumer behaviour professor Brian Wansink shows in his excellent book, ‘Mindless Eating,' many of us over-eat because we eat in response to external cues and distractions rather than a genuine physical need for food. I believe that sitting down to eat (without a TV, computer or book to distract us) focuses our mind on eating and makes us more attuned to physical cues for hunger and satiety.

Moreover, scientists have shown that most of the foods we eat standing up are low in nutritional value and high in empty calories. A study published last year in the Journal of the American Dietetic Association showed that young adults who eat on the run consume more fast foods and soft drinks and less healthy food than their peers who make time to sit down to dinner, eating more fruit and vegetables in the process.

Another investigation conducted by Cornell University researchers showed that time-starved working parents struggle to find the time to sit down to a home-cooked meal. Instead, many of them grab quick foods at work or opt for fast food and take-out meals of inferior nutritional quality.

That sit-down eating can favor healthy weight was shown in a study published recently in the Journal of Pediatrics. Researchers studying children in Greece found that those who regularly sat down to family meals ate more vegetables and fewer snack foods and were thinner than their peers who did not have these eating habits.

How might sitting at a table translate into healthy weight? In part it is because we slow down when we sit down. And slowing down means consuming fewer calories; for when we eat slowly we feel fuller and more satisfied than when we wolf down our food.

Previously considered an old wives' tale, the link between eating quickly and weight gain was recently confirmed by a clever intervention study where healthy adult male volunteers were served a large cup (300 ml) of ice cream on two different occasions. One time, the men were given five minutes to eat the ice cream; the other time, 30 minutes were allotted. Same volunteers, same amount of ice cream - but when people took a half hour to eat the food, their rating of ‘fullness' rose and two gut hormones related to appetite satisfaction increased markedly.

How does any of this relate to cancer prevention? The link is obesity, for excess weight is a key cancer risk factor. The World Cancer Research Fund (WCRF) in its 2009 Policy Report estimates that nearly a fifth of all cancers of the esophagus, pancreas, gallbladder, colon, rectum, breast, endometrium and kidney in the US could be prevented if people had a healthy body weight. (For a global perspective on obesity and cancer, please watch this excellent talk by Professor Philip James, the President of the International Association for the Study of Obesity, given at a WCRF conference I recently attended).

Seen in this light, almost anything we can do to prevent obesity is worth a try - even sitting down to eat!

To practice what I preach, I will spend the next week only eating when seated; then I will report my findings here. Won't you join me? There's room at the table!

Thursday, September 9, 2010

Variety really is the spice of life

A new mantra is making the rounds in dietary cancer prevention circles: ‘Variety, variety, variety.’

No longer content with exhorting us simply to eat five portions of fruits and vegetables a day, scientists now say that consuming a broad and varied range of produce is where it’s at.

So let’s not restrict our vegetable and fruit intake to iceberg lettuce, peas, carrots and bananas (bland foods that many people favor). Instead, why not add more assertively flavored foods to your meal plan, such as leeks, beets, cauliflower, radicchio, parsnips, onions, chard, broccoli, garlic, kale, mushrooms, eggplant, spinach, peppers or red and blue berries?  Only by consuming the broadest-possible range of vegetables and fruits can we obtain the widest-possible spread of nutrients.

When you think about it, this is hardly surprising: Humans did not evolve on a mono-diet comprising only a handful of foods. They survived on whatever the terrain and prevailing seasons had to offer, and this would have translated into a wide variety of foods. By some estimates, our hunter-gatherer ancestors ate more than 800 different types of wild plant foods. These days many of us in the industrialized west are lucky if we get more than 20 different fruits and vegetables into our bodies on a regular basis.  (Or five portions a day, for that matter.)  No wonder our collective health is flagging.

While it is generally accepted that we need to eat a certain amount of greens each day – at least five portions, or about 200 grams each of vegetables and fruits – to maintain health, quantity is not enough. Diversity – eating five portions or 400 grams of different vegetables and fruits a day, and varying these constantly – is increasingly seen as a key to good health.

Talk of dietary diversity in cancer prevention received fresh fuel a few days ago when the medical journal Cancer Epidemiology, Biomarkers & Prevention published a study that found smokers who eat a wide variety of vegetables have a statistically significantly lower risk of developing lung cancer than those whose diet includes little vegetal variety.

The study is drawn from the ongoing, multi-centered European Prospective Investigation into Cancer and Nutrition (EPIC) study, a large-scale investigation involving nearly half a million participants in 10 countries. Scientists sorted the subjects into four groups depending upon how many of 14 fruits and 26 vegetables they had eaten over a two-week period. Those in the top quartile ate between 23 and 40 different fruits and vegetables; those in the lowest quartile ate less than 10 different types.

After tracking participants on average for almost nine years, researchers found that – regardless of the amount eaten – increased diversity of vegetables was linked with reduced risk of lung cancer, especially for smokers. Smokers who ate the greatest variety of vegetables had a 23% lower risk of lung cancer than those consuming the lowest variety. And smokers who ate the greatest variety of fruits and vegetables were 27% less likely to get squamous cell lung cancer, which accounts for 25-30% of all lung cancers.

Of course, this doesn’t mean that you can smoke and still remain healthy as long as you eat your greens. “By far the best way to reduce one’s risk of lung cancer is to stop smoking altogether,” says H. Bas Bueno-de-Mesquita, one of the study’s lead authors and project director of cancer epidemiology at the National Institute for Public Health and the Environment in The Netherlands. However, for the billion smokers worldwide who are addicted to nicotine and find it impossible to quit, eating a variety of vegetables and fruits may represent at least a small risk reduction, he said in an interview.

After years of searching for the Holy Grail of anti-cancer foods – Broccoli sprouts? Green tea? Tomato paste? Turmeric? – scientists increasingly believe that the very combination and interaction of these foods – and many others – may afford the best protection against cancer.

Several studies have suggested that eating a wide diversity of healthy foods may reduce the risk of various cancers, notably those of the digestive tract (see this study, this and this) and breast cancer – even in women with a genetically heightened risk of developing breast cancer. The health effect of a varied diet is most noticeable with vegetables and fruits; varying different types of meat or cereal grains does not appear to have noticeable benefits. (Needless to say, a wide variety of junk foods has no positive health effect at all.)

What this boils down to is that we should embrace dietary variety, consuming many different whole, fresh foods every day. Eating seasonal produce (locally produced for optimum freshness) is an easy way to vary your nutrient intake; as the seasons change, so does the food on your plate. Alas, many people aren’t keen on eating vegetables and fruits; indeed, among the population investigated in the EPIC study, only 23.8% fell into the highest-variety quartile.

Vegetable-phobes may be tempted to substitute a wide diversity of fresh vegetables and fruits with food supplements. However, “a nutritional supplement can never replace the complex matrix of a whole food,” says Dr Bas Bueno-de-Mesquita. As he explains it, each fruit or vegetable contains many different bioactive compounds, none of which can be solely responsible for reducing cancer risk. “A rich mix of vegetables and fruits will expose you to a rich mix of bioactive compounds which may interact and reinforce each other” to help reduce cancer risk, he says.

It may be too early for governments to issue formal recommendations based on these initial findings, but I for one will continue piling my plate high with vegetables and fruits of all sorts. Like everyone, I have good and bad days on the diversity front. Today was good: I ate peppers and onions (breakfast frittata), a nectarine and three plums (snacks), onions, tomatoes, carrots, celery, garlic and dried mushrooms (Bolognese sauce), leeks, broccoli, spring onions and more carrots (vegetable soup).  Can I do it again tomorrow?

For more information on increasing the variety of healthy foods in your diet: Zest for Life, The Mediterranean Anti-Cancer Diet ( 

Tuesday, August 10, 2010

Cancer cells love sugar, and they're not fussy

Pancreatic cancer cells use the sugar fructose to help the tumor grow more quickly, researchers have discovered. Published this month in Cancer Research, these findings serve as a powerful reminder that anyone wishing to curb their cancer risk should start by reducing the amount of sugar they eat.

To assess the effect of fructose on cancer cells, UCLA researchers added glucose to one set of human pancreatic cancer cells and fructose to another set of cells. After letting the cells interact with the sugars, both fructose and glucose were found to increase cancer cell growth at similar rates but through different metabolic pathways. This is the first time a link has been shown between fructose and cancer proliferation.

"In this study we show that cancers can use fructose just as readily as glucose to fuel their growth," said Anthony Heaney, the study's lead author. "The modern diet contains a lot of refined sugar including fructose and it's a hidden danger implicated in a lot of modern diseases, such as obesity, diabetes and fatty liver." While this study was done on pancreatic cancer, these findings may not be unique to that cancer type, Heaney said.

Americans in particular consume large amounts of fructose, mainly in high-fructose corn syrup, a mix of fructose and glucose that is used in soft drinks, bread and a range of other processed foods. High-fructose corn syrup is about 45% glucose and 55% fructose. People also get fructose from sucrose, known as table sugar, which is 50% glucose and 50% fructose.

It has been known for decades that cancer cells thrive on glucose. Moreover, foods that cause a sharp rise in blood glucose (i.e. foods with a high glycemic index (GI) ranking) trigger the secretion of insulin and insulin growth factor (IGF-1), two hormones that also promote cancer growth.

Many health-conscious eaters have therefore shifted to foods with lower GI rankings - an excellent idea if this involves replacing refined, processed starches with natural, whole carbohydrates rich in fiber, protein, fat and micronutrients. However, some people have also switched to fructose-rich sweeteners because these have low GI rankings. Indeed, popular ‘low-carb' weight-loss diets such as the Montignac diet promote the use of pure, crystallized fructose as a sweetener.

More recently, a fashionable sweetener widely touted as a natural and healthy alternative to other sugars has taken the health food community by storm: agave syrup. True, it has a low GI ranking and is ‘natural' to the extent that it is derived from a plant (albeit after intense processing). However, some brands of agave syrup contain as much as 90% fructose.

In the light of the UCLA study, agave syrup may therefore not be helpful for dietary cancer prevention. Indeed, cancer patients would probably be better off avoiding it. Indeed, "efforts to reduce refined fructose intake or inhibit fructose-mediated actions may disrupt cancer growth," the study states.

According to the American Institute for Cancer Research (AICR), commeting on the study on its blog, "the findings are interesting, but more research is needed before it can be used to make recommendations on public health." This is only one study, they note, and it is a cell study. This means that its findings may not necessarily be replicated in animals or humans.

However, the study does highlight that adding sugar to our diet raises cancer risks. "A healthy diet will always include some sugar, as it naturally occurs in nutritious foods like fruit and milk," the AICR writes. "The key is to limit added sugars of all types, rather than focusing on glucose versus fructose or sucrose."

With obesity in the US continuing to rise, "Americans need to cut back on added sugar, no matter where it comes from. Reducing added sugar will help people get to and maintain a healthy weight, and that is one way research clearly shows that we can prevent pancreatic cancer," says the AICR. The WCRF/AICR in its 2009 policy report found that 28% of pancreatic cancers could be prevented if Americans maintained a healthy weight.

In my next post I'll take a look at practical ways to rein in our desire for sugar. It's not as hard as you think!

Monday, August 9, 2010

Mediterranean diet cuts postmenopausal breast cancer risk

Further evidence of the Mediterranean diet's anti-cancer effects has emerged, cheering those of us who believe that this style of eating may be one of the best forms of dietary cancer-prevention around.

In a study that appeared recently in the American Journal of Clinical Nutrition, researchers found that among 14,800 Greek women tracked for a decade, those who stuck most closely to the region's traditional diet were less likely to be diagnosed with breast cancer than those who least closely followed Mediterranean eating patterns.

The link was observed only among women who were past menopause: those with the closest adherence to the Mediterranean diet were 22% less likely to develop breast cancer during the study than those who adhered least to this style of eating.

As I wrote here recently, I believe that Mediterranean-style eating is a key component of lifestyle cancer prevention. Best of all, you don't have to live in a Mediterranean country to reap the benefits of the Mediterranean diet: this term simply describes a pattern of eating that is rich in fresh vegetables, fruits, olive oil, fatty fish, nuts, seeds, garlic, herbs and spices and relatively low in dairy or meat.
The wide variety of fresh plant foods that characterizes this diet provides a vast array of cancer-fighting compounds. These are largely absent from modern western diets which comprise a large proportion of processed meat and factory foods rich in sugar, bleached flour and refined vegetable oils. These types of ‘foods' are thought to provide a fertile ground for cancer cells to grow and spread.

The Mediterranean diet may be breast-cancer protective in several ways. For one, studies (this one or this one) have found that women who closely follow the diet tend to have lower levels of estrogen, a hormone that fuels the growth of the majority of breast cancers.

Moreover, cell studies conducted in laboratories (this one or this one) indicate that the fats in the Mediterranean diet - olive oil and the omega-3 fats in oily fish - may slow the growth of cancer cells.

The Mediterranean diet is also typically rich in flavonoids (in particular, flavones, flavonoids and resveratrol), substances with important antioxidant properties. Antioxidants protect body cells from free-radical damage that can eventually lead to disease, including cancer.

But why should the Mediterranean diet may offer greater protection to postmenopausal than to premenopausal women? According to the study's authors, most younger women who develop breast cancer have a genetic predisposition to the disease, whereas in older women, lifestyle and environmental factors may be more important contributors to risk.

That's not to say that younger women don't also derive benefits from Mediterranean-style eating. As far as I'm concerned, the earlier we can get healthy eating patterns in place (ideally in childhood!), the better armed we are against illness in later life - and not only cancer, but also cardiovascular disease, obesity, diabetes, fertility problems and even depression.

A vast body of research dating back to the 1950s suggests that the Mediterranean diet offers substantial protection against all these conditions. And when paired with other healthy lifestyle habits - regular physical activity, adequate rest, not smoking, and avoiding excessive alcohol intake - the protective effects are even greater.

Friday, August 6, 2010

Strawberries: not just good, but good for you!

Summertime is strawberry time, and I am enjoying it to the full. For I have discovered that the best strawberries don’t come from the supermarket, but from a local farm not three miles from my home.

In the past, strawberry season was an exercise in frustration. Keen to avoid the early berries from Spain (grown in hothouses, tended by underpaid African migrant laborers, sprayed with pesticides and harvested before maturity) I would wait impatiently for the local berries to appear on the supermarket shelves.

However, the season being short and hostage to the vagaries of the local weather, the long-awaited berries rarely made it to my supermarket, or only briefly and at exhorbitant prices. Before I knew it, strawberry season was over and my plans for a freezer full of pureed strawberries had to be shelved until the following year.

A few weeks ago, as I was selecting beautifully fragrant strawberries at the local farmers’ market, the enterprising young grower selling them told me I could come and pick them myself – at half the price he was charging at the market! My family and I went for a short drive to the strawberry farm and as we got out of our car, a beauteous scene unfolded before our eyes: row after row of ruby-red, ripe strawberries glistening in the afternoon sun.

We were handed two wooden crates and set about filling them in the company of the friendly farm dog. Within ½ hour we had picked 8 kilograms of sweet, aromatic mara des bois strawberries, probably the most fragrant of all strawberry varieties, with a flavor resembling the sweet, spicy miniature forest berries you sometimes discover on particularly successful country walks. (They remind us why the Italian name for strawberry is fragola – essentially meaning ‘fragrant.’)

Best of all, the berries had not been treated with any chemicals; to rein in the weeds, the farmer had covered much of his field with black plastic sheeting into which he had cut holes for the strawberry bushes to grow through.

Strawberries are the very incarnation of nutrient-dense food: low in calories (1 cup only contains 43 calories) and brimming with nutrients. Eating just 10 medium-sized strawberries (1 cup or 140 grams) gives you 82 mg of vitamin C – or 136% of the recommended daily average! Strawberries are also rich sources of fiber, potassium, manganese and folic acid.

Strawberries (and other berries, such as raspberries, blueberries, cranberries and blackberries) are also one of our staunchest allies for dietary cancer prevention. A large body of research has established the anti-cancer potential of berry fruit phytochemicals. These include anthocyanins (pigments that impart the attractive colors to berry fruits and colorful vegetables), quercetin (a compound also found in onions, apple skins and tea), proanthocyanidins (common to green tea, grape skin and seeds, blueberries, cranberries, dark chocolate, etc.), tannins (particularly ellagitannins, found in strawberries, black raspberries, red raspberries, blackberries, muscadine grapes, some nuts and oak-aged beverages) and other plant chemicals.

Their cancer-protective effects are multiple: berries contain powerful antioxidants (notably ellagic acid, particularly prevalent in strawberries and raspberries) that protect our cells from free-radical attacks which can lead to cancerous changes. Berry compounds have been shown in laboratory experiments to inhibit cancer cell proliferation and to promote the detoxification of carcinogens. They can even induce apoptosis (cell death when a cell is no longer needed) and reinforce the cancer-destroying effects of certain chemotherapy drugs.

Interestingly, organically grown strawberries appear to have stronger anti-cancer effects than conventionally grown ones. Swedish scientists recently found that extracts of organic strawberries contained higher levels of vitamin C and phenolic compounds than their conventional cousins. Tested on human colon cancer and breast cancer cells, both types of strawberry extract reduced cell growth, but the organically grown ones were more effective at inhibiting proliferation than the conventionally grown ones.

If you can’t obtain organically grown strawberries but have a garden (even a small one will do), strawberries are easy to grow, even for beginners, and are very rewarding. Not only can they carry up to three flushes of fruit throughout the summer, but they are also perennial, meaning that they flower and carry fruit every year, year after year.

So let’s enjoy strawberries while the season lasts! Most often I eat them as they come off the bush, or perhaps cut into creamy ewes’ milk yogurt along with a finely chopped mint leaf and a smidgen of acacia honey. Strawberries elevate any morning smoothie to a feast (I usually add banana and a spoonful of almond butter to make it more filling), as well as lending a lovely burst of color and freshness to porridge or muesli in the morning. To make the season last a little longer, I also puree them and freeze them in ice-cube trays or containers, to enjoy when fresh strawberries have become a distant dream.

To ring in the changes, I recently came up with a savory strawberry sauce that’s delicious with chicken or duck; if you would like to try it, I have posted it on my website.