The Heart of Heart Health
A healthy diet and appropriate lifestyle choices can significantly reduce the risk factors, yet these strategies are greatly under-utilized. People like foods with flavor and often associate heart-healthy foods with a tasteless and boring cuisine. So, food manufactures marketing to health-conscious consumers must include heart-healthy ingredients in a form that’s enticing. The many choices of heart-healthy ingredients can be classed by their tendency to address major risk factors.
Hypertension (high blood pressure) is the major controllable risk factor for such CVD events as myocardial infarction, stroke, heart failure and end-stage diabetes. Some evidence suggests a mere 5mm Hg decrease in blood pressure could equal a 16% decrease in CVD risk. In the U.S., about $15 billion is spent annually targeting the renin-angiotensin-aldosterone system, which controls extracellular fluid volume as a means of controlling blood pressure. In the liver, the enzyme renin converts angiotensinogen to angiotensin I. Angiotensin I is subsequently hydrolyzed to angiotensin II (a potent vasoconstrictor) by angiotensin-I-converting enzyme (ACE). ACE inhibitory drugs have side effects, including hypotension, increased potassium levels, reduced renal function, cough, edema, skin rashes and fetal abnormalities. But, functional food ingredients that contain natural ACE inhibitory peptides and can lower blood pressure could be of great benefit. Studies in hypertensive rats show that caseins and whey proteins from milk contain such ACE inhibitors (casokinins and lactokinins) that can significantly reduce blood pressure. A limited number of human studies have also associated milk protein-derived peptides with statistically significant hypotensive effects. Other sources of natural ACE inhibitors have been found in soy, meat, eggs, cereals, fish and shellfish.
One recently determined functional ingredient source of natural ACE inhibitors is macroalgae. In “Heart Health Peptides from Macroalgae and Their Potential Use in Functional Foods” (The Journal of Agricultural Food Chemistry, 2011, 59, 6829–6836), the potential for bioactive peptides found in microalgae to act as sources of such functionality is explained. Microalgae grow in harsh environments and develop a variety of protective chemicals as a result. Presently in Japan, bioactive peptides are being utilized in several beverage and bakery formulations. The potential for further exploiting this resource is great. Algae are low on the food chain; fit into the needs of even those on the most stringent diets; and have a reputation with consumers as providing a natural source of many healthy compounds (think Spirulina). Microalgae also are currently used as sources of heart-healthy carotenoid antioxidants, specifically astaxanthin.
Addressing Cholesterol and Blood Coagulation
Omega-3 fatty acids have been shown to reduce LDL cholesterol and triglycerides (blood fats), as well as lower blood pressure. Omega-3s, especially EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) tilt the body’s fatty acid metabolism to favor less platelet aggregation, thus offering protection from blood clots. Although fat-soluble, microencapsulation techniques allowed for an explosion of omega inclusions in water-soluble and other food and beverage formulations. Moreover, the extraction of DHA (the most potent form of omega-3) from algae has taken the fish out of fish oil, making omega-3 an even more attractive addition. Many nuts have been shown to help lower cholesterol levels. Walnuts contain omega-3 fatty acids and may improve HDL levels relative to LDL levels in patients with diabetes. Flax and the recently up-trending chia seed also contain omegas in forms suitable for vegetarian applications.
Soluble fibers in many forms not only help consumers to lower cholesterol, they can improve the texture of many foods and beverages. Soluble fiber naturally traps the bile acids that the liver makes from cholesterol to aid in fat digestion and removes them from the body. This forces the liver to pull more cholesterol out of the blood, because recycling of bile acids did not occur. Recent research published in February 2012 in the Journal of Nutrition showed that resistant starch, a type of starch that reaches the large intestines undigested, can increase insulin sensitivity, the tendency of cells to lower blood sugar by responding to insulin. Insulin resistance is a primary feature of type 2 diabetes. Inulin is a form of soluble fiber used to enhance the texture of foods like yogurt and cultured milk (kefir). Unlike resistant starch, inulin is a fructose polymer. Soluble fibers tend to increase satiety of food, which could help reduce caloric intake.
Other means of lowering cholesterol include hindering its absorption and lowering its synthesis. Phytosterols, the plant counterpart of cholesterol extracted from soy beans and pine-tree oils, can inhibit the intestinal absorption of dietary cholesterol. They are added to foods like margarines and to beverages such as orange juice. Garlic, meanwhile, has been shown to lower hepatic synthesis of cholesterol and thus create a modest reduction in cholesterol in individuals with very high levels of LDL cholesterol. Its major form of protection might lie in its tendency to reduce platelet aggregation (clot formation). Foods rich in lignans (in conjunction with other ingredients), flax seed, nuts and whole grains also are associated with lowered risk of CVD.
Quelling Oxidative Damage
The generation of reactive oxygen species, commonly referred to as “free radicals,” is a normal part of biology; a byproduct of respiration; many disease processes; and exposure to environmental toxins. To protect themselves, humans make a variety of antioxidants. And, they are tempted to consume a great deal more due to the tastes, aromas and bright colors of fruits and vegetables that provide nutrient antioxidants—such as vitamins C and E—and carotenoids like -carotene. Other substances in plants, such as flavonoids, could also be cardioprotective, as they show potent antioxidant activity in vitro (test tubes), and because oxidative damage is proposed to contribute to the formation of atherosclerotic plaque. It’s clear from large prospective studies there is an association between foods rich in antioxidants and protection from CVD, but this has not been found to occur consistently with supplementation of individual antioxidants. It is also possible that some of the protection offered by antioxidant-rich foods may be due to their effect on cell signaling, which could affect mechanisms like platelet aggregation.
One highly promising ingredient that has yet to take off in foods and beverages is Coenzyme Q-10 (CoQ-10). CoQ-10 does one job very well, and in doing so, is indispensable to respiration. It shuttles electrons from one enzyme complex to another, moving easily from its oxidized to reduced form and back again as a critical part of the electron transport system. This chain of complexes, bound to the inner membrane of the energy-generating mitochondria of the cell, represents the final stage in the conversion of the fuel people eat into the energy they can use—adenosine triphosphate (ATP)—often referred to as the energy currency of the cell. This is an aerobic system, meaning that it uses oxygen. CoQ-10 is built perfectly for its job, shaped like a hexagonal ring with a long tail consisting of ten 5-carbon units, hence the 10 in the name. There are other CoQs, such as CoQ-9 or CoQ-7, that exist in other species of animals. The long tail makes CoQ-10 fat soluble, allowing it to imbed in membranes, which are bilayers of specialized fats called phospholipids.
CoQ-10 is found in greatest abundance in tissues that need energy, those with the greatest concentration of mitochondria. Liver, kidney, cardiac muscles and muscles of aerobically-trained athletes are particularly rich in CoQ-10. In fact, CoQ-10 was first isolated from beef heart. It has long been postulated that decreases in CoQ-10 levels in blood and in the heart are risk factors in various forms of heart disease, in particular congestive heart failure. Karl Folkers, Ph.D., and Gian Paolo Littarru, Ph.D., working separately, demonstrated a deficiency of CoQ-10 in human heart disease as early as 1972.
There are several reasons why CoQ-10 can aid the ailing heart or help to prevent the onset of heart disease. The most obvious relate to the energy available to the heart muscle. Low levels of CoQ-10 could impair the working of the electron transport chain responsible for the production of ATP. Impaired contraction of heart muscles means lowered ability of the heart to force blood out of the left ventricle and into the circulation, a parameter known as ejection fraction. Indeed, this parameter is reported to improve the administration of supplemental CoQ-10.
“Bioenergetics” doesn’t describe the whole story of CoQ-10. In fact, the body makes at least 10 times as much as would be necessary to run the electron transport chain. This isn’t simple redundancy given its importance to energy, but rather represents another critical function of CoQ-10—that of an antioxidant—but not just any antioxidant. Antioxidants donate electrons to dangerous free radicals—substances with unshared electrons that are attracted to a partner with which to bind. This causes a sort of “biological rust” that can cross-link proteins and damage membranes or even DNA. Oxidized LDL cholesterol, for example, is a risk factor in the formation of atherosclerotic plaque. Once radicals satisfy that need, the antioxidant is spent and can no longer donate electrons. It’s said to be oxidized and must return to its reduced form by gaining electrons.
As an antioxidant, CoQ-10 is unique, because it has an endless source of regenerating electrons in the electron transport chain. As long as humans are breathing, electrons are run through the system to create energy. So, for CoQ-10, its dual roles are complementary. It also is believed to help other antioxidants, such as vitamin E, by providing electrons for their regeneration.
Adding up the methods by which CoQ-10 can protect the heart, the list includes: increased energy to the heart muscle; protection against oxidative products that can place one at risk for the formation of atherosclerotic plaque; protection from ischemic injury to the heart muscle; reduction of hypertension; and regeneration of other antioxidants to enhance their protection. This makes CoQ-10 a formidable cardioprotective agent.
Recent research uncovered yet another way in which CoQ-10 might help the heart. The most potent of the cholesterol-lowering drugs, referred to collectively as statins, work by reducing the liver’s ability to make cholesterol. Statins act by inhibiting an enzyme that assembles the 5-carbon compound used to make the cholesterol rings. It’s the same 5-carbon compound that makes the tail of CoQ-10. That means statins can lower CoQ-10, potentially reducing critical energy. Taking CoQ-10 with statin drugs limits this potential problem, something Folkers repeatedly emphasized from the beginning of the use of these drugs.
Although the body makes its own CoQ-10, status can diminish with age and the antioxidant demands of different diseases, making supplementation a prudent choice. Although CoQ-10 is a difficult molecule to absorb and integrate into foods, techniques such as microencapsulation allow CoQ-10 to be used in solution. This and other methods are allowing CoQ-10 to merit increased consideration as another serious defense tool in the heart-health arsenal. NS
Flavonoids and Free Radicals
The following are some of the flavonoids under study:
* Anthocyanidins are a subclass of flavonoids found in dark red and blue grapes, and berries.
* Flavanols include catechins in green and white teas, chocolate, grapes, berries and apples.
* Theaflavins occur in black and oolong teas.
* Proanthocyanidins are found in chocolate, apples, berries, red grapes and red wine.
* Citrus fruits contain flavanones such as hesperetin and naringenin.
* Flavonols, such as quercetin and kaempferol, are found in yellow onions, scallions, kale, broccoli, apples, berries, teas.
* Soyfoods contain isoflavones that have a weak estrogen-like activity in mammals. The effect of soy protein on plasma cholesterol levels has earned soy an FDA health claim.