Dr. Perricone's No. 10 Superfood: Yogurt and Kefir
July 15, 2005
"Probiotic" Partners in Health The origin of fermented foods and cultured milk products goes so far back that it is rumored to predate recorded history. This is perfectly in keeping with my philosophy that the most ancient foods have survived for a reason—they continue to be instrumental to the survival of our species. Fermented and cultured foods may well represent our first experience with what researchers now call "functional" foods—foods that actively promote optimal health.
The fermented foods scientists consider "probiotic" are primarily yogurt and kefir.
Learn more about the benefits of yogurt and kefir:
What Are Probiotics and What Do They Do? Early in the 20th century, research by Nobel Prize–winning biologist Dr. Elie Metchnikoff led him to propose the "intoxication theory" of disease. Metchnikoff believed that aging was accelerated by toxins secreted by unfriendly bacteria that putrefy and ferment food in the intestines. He also believed that the harmless bacteria in fermented milk products might explain the longevity of certain ethnic groups—most notably the peoples of the Caucasus Mountains of southern Russia.
Accordingly, Metchnikoff recommended consuming "cultured" foods, such as yogurt, that contain healthful bacteria. His ideas spread rapidly, and in short order, both yogurt and the concept underlying probiotics garnered world attention. And because Metchnikoff identified lactic acid–secreting bacteria as among the most beneficial, these so-called lactobacilli became an early focus of popular efforts to put Metchnikoff's hypothesis into practice. Today, probiotic microbes are routinely fed to livestock, and it is widely accepted that various lactobacillus and bifidobacteria species hold great promise for enhancing human health.
In humans, probiotic microbes help the body's ongoing fight against infectious diseases by competing with the pathogens for food, nutrients and survival. This is why human breast milk is rich in nutritional factors that foster the growth of bifidobacteria—a beneficial bacterial family that keeps babies' intestinal ecosystems healthy and disease-resistant.
Probiotics vs. Disease
Preliminary research supports probiotics' potential to prevent or treat many common conditions (more research is needed, however, so don't rely on probiotics to help treat any health condition without medical supervision). Probiotics:
Ameliorate vaginal (bacterial and yeast), urinary tract and bladder infections
Ameliorate inflammatory intestinal disorders, including inflammatory bowel disease (IBD)
Ameliorate food allergies and inflammatory, allergic conditions like asthma and eczema
Reduce several risk factors for cardiovascular disease
Reduce several risk factors for intestinal cancers
Reduce the duration of gastroenteritis and rotavirus-induced diarrhea in infants
Reduce the rate of childhood respiratory infections
Ameliorate microbe-induced traveler's diarrhea
Help prevent tooth decay
Probiotics, Inflammation and Immune Function
Researchers have found that people whose diet is rich in probiotics foods enjoy enhanced immune function. It appears that probiotics normalize immune responses, inhibit chronic subclinical inflammation and may improve inflammatory conditions with an autoimmune component, such as asthma, eczema and Crohn's disease.
Today there is an alarming emergence of disease-causing agents (viral, bacterial, etc.) that are resistant to antibiotics. These dire and potentially life-threatening circumstances have prompted urgent research into the use of probiotic bacteria to battle infections. We now know that probiotics can raise antibody levels in the body. This immune-system boost reduces the risk of infections taking hold in the first place, thus avoiding the need for antibiotics. Many doctors recommend live yogurt for patients on antibiotics to replenish good bacteria and some argue that yogurt live cultures may also reduce the occurrence of colds, allergies and hay fever.
Yogurt vs. Obesity A daily dose of yogurt is good for people of all ages. Yogurt is also important for those wanting to lose weight. As a milk product, yogurt is naturally rich in calcium. Research shows that calcium helps reduce weight gain. Even small changes in the calcium levels of fat cells can change signals within the cell that control the making and burning of fat.
The authors of a 2003 study at the University of Tennessee placed 34 obese people on a low-calorie diet. Sixteen of them were given 400 to 500mg of calcium in the form of a daily supplement. The other 18 people ate a diet higher in calcium— 1,100mg per day—in the form of yogurt. After 12 weeks, both groups lost fat. The supplement-taking group had 6 pounds less fat, but the yogurt group lost about 10 pounds of fat. And, those who ate yogurt discovered that their waists shrank by more than an inch and a half. In comparison, the supplement-taking subjects lost only about a quarter of an inch in waist size. Finally, a whopping 60 percent of the yogurt eaters' weight loss was belly fat, while only 26 percent of the supplement group's loss was belly fat.
This is very exciting news as belly fat—which doctors call visceral or intra-abdominal fat—is linked to high cholesterol, high insulin, high triglycerides, high blood pressure and other problems. Visceral fat may also secrete more disease-linked inflammatory molecules than other types of fat.
The study also reported that in addition to helping the participants lose more weight, the group that ate yogurt was about twice as effective at maintaining lean muscle mass. As the study director, Michael Zemel, PhD, stated in a news release, "This is a critical issue when dieting. You want to lose fat, not muscle. Muscle helps burn calories, but it is often compromised during weight loss." I couldn't agree more!
Always buy organic yogurt and avoid yogurt that contains thickeners and stabilizers. Also avoid yogurt that contains added sugars or sweetened fruit, as these upset the delicate chemical balance that allow the cultures to thrive. Sugars also feed the growth on unwanted yeasts, such as Candida albicans.
I start every morning by pouring myself a glass of unsweetened whole milk kefir and add to it 2 tablespoons of POM Wonderful (pure pomegranate extract). I stir it up and it looks and tastes like a rich and beautiful berry smoothie. It is the perfect way to start the day.
Kefir (kee-fer) is a fermented, probiotic milk drink from the Caucasus Mountains in the former Soviet Union. The name kefir loosely translated means "pleasure" or "good feeling." Due to its health-promoting properties, kefir was once considered a gift from the gods. Fortunately it is being rediscovered and recognized for its many health and beauty benefits.
Kefir can best be described as a sort of liquid, sparkling yogurt, with its own distinct and deliciously mild, naturally sweet, yet tangy flavor—with a refreshing hint of natural carbonation. Its unique taste and almost mystical reputation as a longevity elixir explains why people all over Europe are making kefir (along with similar fermented drinks) their beverage of choice. Sales are even beginning to rival top soft drink brands.
Unlike yogurt, which is created from milk by adding certain lactic acid bacteria, kefir is made by combining milk with a pinch of "kefir grains"—the folk term coined to describe a complex mixture of yeasts and lactobacillus bacteria. The small amount of carbon dioxide, alcohol and aromatic compounds produced by the cultures give kefir its distinct fizzy, tangy taste.
Kefir also contains unique polysaccharides (long chain sugars) called kefiran, which may be responsible for some of its health benefits. Much of the Russian research on its health benefits remains untranslated, and Western research is in its early stages—but the results to date support kefir's impressive folk reputation.
Kefir dates back many centuries—likely even longer—to the shepherds of the Caucasus Mountains, who reportedly discovered that fresh milk carried in leather pouches would occasionally ferment into an effervescent beverage.
Another legend, from the Islamic peoples of the Caucasus Mountains, claims that kefir "grains" were a gift to the region's Orthodox Christians from Mohammed, who strictly forbade their dissemination, because they would lose their "magic strength." Although Marco Polo mentioned it in his travel accounts, kefir and its secrets remained unknown outside the Caucasus region until reports spread of its value in treating tuberculosis, and for intestinal and stomach disorders. Russian doctors of the Victorian era believed that kefir was beneficial for health and the first scientific studies for kefir were published in the late 19th century.
This mildly self-carbonated beverage continues to be popular in the Caucasus, Russia and southwestern Asia, and recently gained wide popularity in Western Europe. In the United States, most natural food stores and the "whole food" chain markets found in urban areas—such as Whole Foods Market and Wild Oats—carry kefir. Given the ever-increasing popularity of yogurt and yogurt drinks here, I predict it won't be long before the big U.S. supermarket chains follow suit. However, as with yogurt, beware of products laden with sugars and fructose. Buy plain, unsweetened kefir and flavor with mixed berries, including açaí.
Kefir's Health Benefits
In addition to kefir's ancient reputation as a healthy drink, it has been famously credited with the extraordinary longevity of people in the Caucasus. Hospitals in the former Soviet Union use kefir—especially when no modern medical treatment is available—to treat conditions ranging from atherosclerosis, allergic disease, metabolic and digestive disorders and tuberculosis to cancer and gastrointestinal disorders.
A number of studies conducted to date have documented kefir's ability to stimulate the immune system, enhance lactose digestion, and inhibit tumors, fungi and pathogens— including the bacteria that cause most ulcers. This makes a lot of sense as scientists have since discovered that most ulcers are caused by an infection with the bacterium, Helicobacter pylori and not spicy food, stomach acid or stress, as physicians erroneously believed for years.
Scientists are now discovering that a great many inflammatory diseases (including certain types of heart disease) can be triggered by a bacterium. And that provides all the more reason to enjoy kefir as part of your daily diet.