What you should eat

I’ve read about all the things I shouldn’t eat,” wrote one reader.  “What I want to know is, what should I eat?”  That letter was my inspiration in writing today’s column, as we celebrate Nutrition Month this July.

She’s not actually alone.  Many people know that they should cut back on foods like burgers, pepperoni pizzas, potato chips, milk shakes, and sodas, but they may not know what a healthy diet should look like and which foods are good for what conditions.  Despite (or maybe because of) all the diet books, food pyramids, and expert advice, most people are still confused.

Yet, we know which diets can lower the risk of heart disease, the major cause of death among Filipinos.  Odds are, these same foods can also promote weight loss, prevent cancer, protect the eyes, and stay regular with your bowel movements.  The tricky part is summing up an entire diet in simple, easy-to-remember advice.  Here’s our try.

Which foods are good for what

It’s usually not a single food, but a class of foods or an entire diet, that protects against (or promotes) a disease.  It’s not just spinach, but all lutein-rich green leafy vegetables, that may protect your eyes.  And it’s not just bananas or other potassium-rich foods, but a DASH diet (which is rich in fruits and vegetables and low in saturated fat and added sugars), that may lower your blood pressure.      Here’s what we know about which foods lower (or raise) the risk of some key health problems.

Lowering cholesterol

“The soluble fiber in any single food has only a modest impact on LDL (“bad”) cholesterol,” explains Alice Lichtenstein, director of the Cardiovascular Nutrition Laboratory at Tufts University in Boston.  “However, if you’re eating beans, fruits, vegetables, oats, and other foods with soluble fiber instead of burgers, pizzas, and shakes, it adds up to a sizeable benefit.”

The plant sterols that are added to some juices, margarines, and yogurts make a bigger dent.  “There’s good evidence that they decrease LDL cholesterol levels on average by about 10 percent,” notes Lichtenstein.  “Polyunsaturated fats win out over monounsaturated fats because they lower LDL a bit more,” explains Lichtenstein.  That means replacing butter with high-mono oils like canola, corn, and sunflower.  It also means replacing red meat and cheese with poultry and fish. 

To summarize:  Best = oils, nuts, fatty fish (foods high in unsaturated fats).  Second  best =  plant sterols.  Beans, oats, psyllium (foods high in soluble fiber).  Worst = meat, butter, cheese, cream, frosting, pie crust (foods high in saturated or trans fat).  Don’t forget = To lower triglycerides, cut back on refined grains and added sugars.

Protecting eyes

“Eat a variety and abundance of colorful plant foods,” advises Julie Mares, professor of ophthalmology at the University of Wisconsin School of Medicine and Public Health.  But what if you had to single out one group of foods?  “At the top of my list are dark leafy greens,” says Mares.  That means spinach, kale, collards, and Swiss chard.  Peas, broccoli, and other green vegetables are rich in lutein and its cousin, zeaxanthin.  “They’re the predominant carotenoid in both the lens and the retina, and specifically in the cone-rich area of the macula,” says Mares.  “That’s the part of the retina that’s used to see fine detail, like reading a pill bottle or newspaper.”

Age-related macular degeneration is a major cause of blindness in older people.  And the lens is where cataracts form.  A number of studies have found a lower risk of cataracts and advanced macular degeneration in people who consume more lutein and zeaxanthin.  “There’s strong compelling evidence for a potential protective effect of these carotenoids,” notes Mares.

To summarize:  Best = kale, collards, spinach, Swiss chard (lutein-rich foods).  Second best = salmon, sardines, herring, mackerel (fatty fish).  Worst = soft drinks, sweets, white bread, pasta, rice (refined grains and added sugars).  Don’t forget = Studies are testing vitamins C and E, lutein, and fish oils to show if they slow muscular degeneration.  High doses of B vitamins lowered the risk of macular degeneration in a large study of women at risk for heart disease.

Preventing colon cancer

“Milk probably reduces colorectal cancer risk,” concluded the World Cancer Research Fund and the American Institute for Cancer Research in 2011. (The WCRF and AICR periodically convene a panel of scientists to review the scientific evidence on lifestyle and cancer.)
How might milk or calcium protect the colon?  “It may lower cell proliferation in the lining of the colon,” says Amanda Cross, an investigator in the Division of Cancer Epidemiology and Genetics at the US National Cancer Institute in Bethesda, Maryland.  “Increased proliferation can elevate cancer risk.”

The AICR also decided that “foods containing dietary fiber, such as fruits, vegetables, whole grains, and beans, reduce the risk of colorectal cancer.”  On the other hand, the AICR calls as a “convincing” cause of colon cancer red meats (beef, pork, and lamb) and processed meats (like ham, bacon, pastrami, salami, hotdogs, and sausages).  The recommendation from the WCRF and AICR is to limit red meat to 18 ounces per week and to avoid processed meats,” notes Cross.  How might they harm the colon?  “Meat is a source of laterocyclic amines, polycyclic aromatic hydrocarbons, and N-nitroso compounds,” explains Cross.  “All have been shown to induce tumors in animal models.”  The first two (HCAs and PAHs) can show up in any meat, poultry or seafood.  “They’re formed when meat is cooked well done by high-temperature methods like barbecuing,” says Cross.

To summarize:  Best = low-fat milk (calcium-rich foods).  Second best = whole grains, beans, vegetables, fruit (fiber-rich foods).  Worst = bacon, hotdogs, sausages, lunch meats, beef, pork, lamb (red or processed meats).  Don’t forget = Regular colonoscopies can prevent colon cancer by removing precancerous polyps.  To lower prostate cancer risk, men should limit calcium to 1,200 mg a day (from foods and supplements combined).

Staying regular

What’s the best food for staying regular?  “Wheat bran is at the top list, followed by other brans like rye, corn, and oat,” says Joanne Slavin, professor of food science and nutrition at the University of Minnesota.

That’s because most of the fiber in wheat bran — celluloses and hemicelluloses — survives the trip through your gut.  “Probably half is still there at the end,” explains Slavin.  “And they bind to water, so they have the most effect on stool weight.”  After brans come beans.  “Beans have far more fiber than fruits or vegetables,” she notes.  What’s lowest on Slavin’s list?  “White fibers that are purified, like pectin and inulin.  “The purified fibers are pretty much all broken down by the end,” explains Slavin.  “There’s zero fiber left in fecal samples, so they don’t have a big role in increasing stool weight.”

What about those old standbys, prunes and prune juice?  “Prunes absolutely work,” says Slavin.  But it’s not just fiber that explains the magic of prunes.  Their naturally occurring sugar alcohol sorbitol may also make a difference.  And what’s worst for regularity?  Foods don’t have much impact, says Slavin.  But “iron supplements — and many medications — are constipating.”

To summarize:  Best = wheat bran.  Second best = beans, prunes, psyllium.  Worst = iron supplements.  Don’t forget = “High-fiber” cereals, bars, and other foods made with inulin, maltodextrin, and other isolated fibers won’t help.

Lowering blood pressure

High blood pressure — or hypertension — boosts your odds of having a heart attack or stroke (a “brain attack”).  And what foods help keep blood pressure in check?  “I would emphasize fresh fruits and vegetables that are high in potassium,” says Dr. Norman Kaplan, author of the classic textbook, Kaplan’s Clinical Hypertension, now in its 10th edition.  Topping the list are green leafy vegetables (like spinach, Swiss chard, and beet greens) and deep orange vegetables (like butternut squash and sweet potatoes).  Bananas, cantaloupe, and mushrooms are also potassium-packed.  So are fish, beans, milk, and yogurt.

The DASH (Dietary Approaches to Stop Hypertension) diet — which is rich in fruits, vegetables, and low-fat dairy foods but low in saturated fat, added sugars, and refined flour — is the diet of choice.  How does potassium work?  “It’s hard to say for sure, but if you lower potassium levels inside cells experimentally, it makes blood vessels constrict,” explains Kaplan.  Stiff, inflexible arteries are a major cause of high blood pressure, especially in older people.  What’s bad for blood pressure is a no-brainer:  too much salt.  “Primarily, the mechanism is that sodium expands the volume of blood in the circulation,” says Kaplan.  “As volume increases, pressure goes up.  When we go on a lower-sodium intake, the overall volume goes down.”

To summarize:  Best = vegetables, fruits, fish, low-fat milk, yogurt (potassium-rich foods).  Second best = beans (foods high in plant protein).  Worst = soups, processed meats, pizzas, restaurant dishes (high-salt foods).  Don’t forget = Aim for a DASH-like diet (high in fruits and vegetables and low in saturated fats and added sugars).  That also lowers LDL (“bad”) cholesterol.