Should Your Food Choices Be Dictated By Your Blood Type?

Should blood type guide your food choices?
Dietary advice has stamina but isn't worth its weight in salt, experts say.

While searching for relief from migraines and general malaise, a friend recently consulted a nutritionist who told her, matter-of-factly, that because she has Type O blood, she should be eating lots of meat and eliminating gluten, dairy and many grains. A Chinese medicine doctor she consulted confirmed the advice, saying, basically: Duh.

For someone who had hoped to go vegetarian — and who is among the 45 percent of people in the U.S. with Type O blood — the news was surprising.

But was it true?

The idea of eating according to your blood type became popular with the 1996 book "Eat Right 4 Your Type" (Putnam Adult) by Peter D'Adamo, a naturopath physician. The theory is that the genes behind blood type also are behind the expression of other proteins in our body, which relate to how we digest foods.

Type O's, having the oldest blood type, draw on our hunter roots and perform best on lean meats (including fish), fruits and vegetables, as well as with intense exercise, while gluten, some beans and dairy lead to weight gain, sickness and sluggishness, the theory posits. The proteins in legumes and dairy tend to cause inflammation in Type O's, goes the theory, so without meat it's difficult to fulfill their protein needs.

Rather than banning Type O's from being vegetarians, D'Adamo said, "a more helpful way of thinking is that people who are blood Type O may want to explore a more high-protein, lower-carbohydrate lifestyle in lieu of their current dietary choices, should they suffer from signs that they are not getting enough protein in their diets: digestive disorders, fatigue, low immunity or slow metabolism."

Meantime, people with blood Type A do best as vegetarians, B's are hardier omnivores and ABs are a combination.

Most nutritionists do not subscribe to eating by blood type because it is not backed by hard scientific data, said Marjorie Nolan, a dietitian and spokeswoman for the American Dietetic Association.

The evidence supporting the blood-type diet is based largely on anecdotes and research showing links between blood type and certain illnesses (for example, Type O's are more likely to have stomach ulcers). There have been no peer-reviewed studies published showing that different blood types perform better on certain foods.

D'Adamo says small-scale studies his team has conducted looking at improvements in digestive malabsorption may serve as templates for larger studies, but those will be expensive, complicated and time-consuming.

Dr. Michael Greger, founder of NutritionFacts.org, said the premise of the blood-type diet is wrong: The blood-type system, which predates humans, is far more complicated than just ABO, he said.

"People crave individualized, personalized science, but this is pseudoscience," said Greger, a general practitioner specializing in clinical nutrition.

People who lose weight or feel better after starting the blood-type diet could actually be uncovering an allergy, or may just be eliminating junk food, Greger said.

While she applauds D'Adamo's marketing, Dr. Ingrid Kohlstadt, editor of the medical textbook "Food and Nutrients in Disease Management" (CRC Press) and an associate at Johns Hopkins Bloomberg School of Public Health, said the connection between blood type and susceptibilities is not strong enough to be meaningful from a medical or public health perspective. She said she would rather prescribe a diet according to a person's gum health, which is strongly associated with heart disease, than his or her blood type.

On the plus side, any of the four blood-type diets is healthier than how most Americans eat, Kohlstadt said.

Source:October 26, 2011|By Alexia Elejalde-Ruiz, Tribune Newspapers

What Foods Are the Best to Eat Before a High-Stakes Test?

With test-taking season upon us, Sue Shellenbarger on Lunch Break looks at the latest findings from the science of studying. For students approaching SAT/ACTs, midterms and finals, which memory tricks work best and does cramming help?

Chiefly, testing yourself repeatedly before an exam teaches the brain to retrieve and apply knowledge from memory. The method is more effective than re-reading a textbook, says Jeffrey Karpicke, an assistant professor of psychological sciences at Purdue University. If you are facing a test on the digestive system, he says, practice explaining how it works from start to finish, rather than studying a list of its parts.

In his junior year of high school in Cary, N.C., Keenan Harrell bought test-prep books and subjected himself to a "relentless and repetitive" series of nearly 30 practice SAT college-entrance exams. "I just took it over and over again, until it became almost aggravating," he says.

Practice paid off. Mr. Harrell, now 19, was accepted at University of North Carolina-Chapel Hill, a college he's dreamed of attending since the third grade. He scored 1800 (out of 2400) on the SAT, up 50% from 1200 on the PSAT, a preliminary test during his sophomore year.

Taking pretests "felt like hard work," Mr. Harrell says, but seeing steady increases in his scores boosted his confidence. Practice tests also help with test-taking skills, such as pacing, says Paul Weeks, vice president of educational services for the ACT, which creates and administers college-entrance exams.

Repeated practice tests help master test format and pacing.

Sleep also plays a role in test performance, but in two unexpected ways. Review the toughest material right before going to bed the night before the test. That approach makes it easier to recall the material later, says Dan Taylor, director of a sleep-and-health-research lab at the University of North Texas in Denton. And don't wake up earlier than usual to study; this could interfere with the rapid-eye-movement sleep that aids memory, he says.

A common study habit—the all-nighter—is a bad idea. Although 60% of college students stay up all night at some point in school, the practice is linked to lower grades, says Pamela Thacher, an associate professor of psychology at St. Lawrence University in Canton, N.Y., based on a 2008 study of 120 students. It also impairs reasoning and memory for as long as four days.

Being Confident

Write down fears and anxieties before the test to free working memory and prevent distractions during the test.

To combat self-doubts (such as 'I'm bad in math'), remind yourself of proven personal traits and strengths that can propel you to success.

Practice in advance facing all the pressures you will face on exam day, such as driving to the testing center or visiting an unfamiliar testing room.

Test yourself by recalling broad concepts rather than trying to memorize facts or re-reading textbooks.

Before the test, envision yourself answering questions calmly and with confidence.

Everybody knows you should eat breakfast the day of a big test. High-carb, high-fiber, slow-digesting foods like oatmeal are best, research shows. But what you eat a week in advance matters, too. When 16 college students were tested on attention and thinking speed, then fed a five-day high-fat, low-carb diet heavy on meat, eggs, cheese and cream and tested again, their performance declined. The students who ate a balanced diet that included fruit and vegetables, however, held steady, says Cameron Holloway, a senior clinical researcher at the University of Oxford. The brain requires a constant supply of energy and "has only a limited backup battery," he says.

While many teens insist they study better while listening to music or texting their friends, research shows the opposite: Information reviewed amid distractions is less likely to be recalled later, says Nicole Dudukovic, assistant professor of psychology at Trinity College, Hartford, Conn.

In her research, college students categorized and made judgments about pictures of more than 100 items. Then, they were tested on a new mix of pictures and asked to recall which ones they had already seen and how they had categorized them; half the time, they were also asked to listen and respond to a set of rhythmic sounds. When the students were tested later, they were more likely to remember correctly what they had studied without distractions.

"Students do have this belief that they can do it all and they aren't really being distracted" by music or sounds from a noisy cafe, Dr. Dudukovic says. But while the sounds may "make them feel more relaxed," she says, they won't help them ace the midterm.


Bryan Almanza says he did poorly on the PSAT as a high-school sophomore because he didn't know how to prepare. He got too little sleep the night before and ate only a bowl of cereal for breakfast. On the test, some hard physics questions made him nervous and distracted, says Mr. Almanza, 18, a senior at Campbell High in Smyrna, Ga. "I'm going to fail," he remembers thinking at the time. A test-prep program at his school taught him to get plenty of sleep, eat a good breakfast and pace himself on the test. By staying calm, optimistic and focused, he raised his score significantly on the SAT.

Source: Wall Street Journal 10/26/11

Food Choices Matter

If there was ever any suggestion that French fries are good for you, it’s now dispelled in stark detail. An analysis of data from three lengthy surveys that assigns actual pounds of weight gain to foods finds that fries, sodas and several other guilty pleasures are among the most potent waist expanders.

On the bright side, researchers attribute weight loss to eating yogurt, fruit, nuts and vegetables. The report appears in the June 23 New England Journal of Medicine.

“Conventional wisdom often recommends ‘everything in moderation’ with a focus only on total calories consumed, rather than the quality of what is consumed,” says study coauthor Dariush Mozaffarian, a cardiologist at Harvard Medical School and Brigham and Women’s Hospital in Boston. “Our results demonstrate that the quality of the diet — the types of foods and beverages that one consumes — are strongly linked to weight gain.”

Mozaffarian and his colleagues combined data from three long-term surveys conducted between 1986 and 2006 that included more than 22,000 men and nearly 100,000 women. The weight, diet and lifestyle information collected in those surveys enabled the researchers to calculate an effect for specific foods.

None of the participants was obese or had any serious medical problems at the study’s outset, and no one was asked to go on a diet. Starting with each volunteer’s weight at the outset, the researchers monitored any gain or loss at four-year intervals. On average, participants had gained 3.35 pounds at each four-year point.

Potatoes stood out as a culprit. A single-serving bag of potato chips added to one’s daily intake tacked on 1.69 pounds over four years by this calculation. Potatoes prepared as boiled, mashed or baked, added about half a pound, while French fries larded on 3.35 pounds. A single sugar-containing soft drink per day tacked on 1 pound every four years. Butter, refined grains, desserts, processed or red meats, fruit juice, fried food or foods containing trans fats added somewhat less weight.

Other foods seemed to lower weight. Adding a daily serving of yogurt knocked off nearly a pound over four years, while adding a serving of nuts or fruit was associated with a loss of about half a pound each. An extra serving of whole grains, vegetables or diet soft drinks reduced weight slightly.

Changes in intake of dairy products other than butter and yogurt, whether low-fat or not, appeared to have little effect on weight.

A pound here and a pound there might not seem worth worrying about, but weight gain in middle age is often so gradual that people don’t notice it until they have already gained a substantial amount, Mozaffarian says. “These ‘small amounts’ are exactly what is causing the obesity epidemic,” he says.

Specifying which foods may lessen or prevent weight gain is highly practical, says nutrition scientist Christopher Gardner of Stanford University, who wasn’t involved in this study. “When you choose one of these foods, you choose not to consume something else,” he says. The strength of the study, he says, is that it demonstrates that “these are achievable differences because real, live people did them.”

Source: Science News 6/22/11