Into the Heart

Six Brussels Sprouts . . . strong blood vessels.

A primary role of vitamin C in preventing coronary vascular disease is by maintaining the integrity and stability of the vascular wall. Vitamin C deficiency results in the weaking of connective tissue and loss of endothelial barrier function. Vitamin C interacts with lipoproteins, coagulation factors, prostaglandins, nitric oxide and second messenger systems.

In lipoprotein metabolism low density lipoproteins (LDL), Lp(a) and very low density (VLDL) are inversely correlated with vitamin C concentrations. HDL levels are positively correlated.

Vitamin C helps HDL production, which leads to an increased removal (uptake) of lipids deposited in the vascular wall and to a decrease of the atherosclerotic lesion. Vitamin C is known to stimulate 7 a hydroxylase, a key enzyme in the conversion of cholesterol to bile acids. 

In prostaglandin metabolism vitamin C increases prostacyclin and prostaglandin E levels (vasodilators)and decreases thromboxane (vasoconstrictor) levels. Essentially, vitamin C deficiency induces vascular constriction, as well as cellular and extracellular defense mechanisms in the vascular wall.

On a healthy note, Brussels Sprouts are high in vitamin C.  The Daily Reference Intake (DRI) for vitamin C is 75 mg.  Six Brussels Sprouts contain about ninety percent of the daily requirement for vitamin C. Brussels Sprouts are also a good source of Folate (54 mcg), and Vitamin A (777 IU) and Vitamin K (400 mcg).

Collagen is the most abundant protein synthesized in the body and is the major component of connective tissue. Vitamin C is essential for the building of collagen. Although the daily reference intake (DRI) for vitamin C is 75 mg, to maintain healthy blood vessels (and bones) a primary goal is to incorporate 500 mg of vitamin C daily.

Keep in mind, cooking diminishes vitamin C potency. Lightly steaming Brussels Sprouts and drizzling with olive oil (not butter) will maintain vitamin C integrity. The olive oil will increase the bioavailability of the nutrients.

Vitamin C increases the production of infection-fighting white blood cells and antibodies and increases levels of interferon. Interferons direct the immune system's attack on viruses, bacteria, tumors and other foreign substances that may invade the body. Once interferons have detected and attacked a foreign substance, they alter it by slowing, blocking, or changing its growth or function.

Blood Vessels, Bone & Vitamin C

Eight ounces of calcium fortified orange juice helps maintain blood vessel and bone integrity. Tissues most sensitive to Vitamin C status are those which contain large amounts of collagen such as blood vessels, and bone.

Vitamin C dependent reactions cover a broad range of functions that include phagocytic activity, neurotransmitter synthesis, and hepatic production of bile from cholesterol.

Vitamin C extends vitamin E activity by reducing oxidized tocopherol so that it may again function as an antioxidant. It also improves bioavailability of inorganic dietary iron by maintaining the reduced form which is more soluble and readily absorbed.

Vitamin C is found only in foods of plant origin. Fruits and vegetables are the best sources. An eight ounce serving of calcium fortified orange juice contains 450 mg of potassium, 120 percent of the daily requirements for Vitamin C, 35 percent of the daily requirements for calcium and 25 percent of the daily requirements for vitamin D. Calcium fortified orange contributes to healthy blood vessels and strong bones.

Unsweetened orange juice is a Low Glycemic Index Food (GI 54 or less), it generates a slow rise in blood-sugar. Blood sugar spikes contribute LDL cholesterol becoming oxidized. When LDL cholesterol becomes oxidized (rancid) it causes a cascade of inflammatory reactions that contribute to atherosclerosis: coronary artery disease.

Estrogen & Arterial Tissue

The protective effects of estrogen in the cardiovascular system results from both systemic effects and direct actions of the hormone on the blood vessels.

The artery is composed of three intricate layers of tissue. The inner most layer, closest to the blood is called the intima. The middle layer of the artery, the media is composed of smooth muscle cells. Middle layers fibers are primarily made of two proteins, collagen and elastin. The middle layer changes vessel diameter to regulate blood flow and blood pressure.

The outermost layer, the aventitia is composed of connective tissue and small blood vessels that feed the walls of large arteries. These three layers of the artery wall surround the lumen, the opening that blood flows through. Snuggled up to the intima is a thin layer of endothelial cells. These endothelial cells are the gatekeeper of the artery.

Receptors for estrogen have been identified in all components of the vascular wall: endothelium, smooth muscle, adventitial cells. As such, for post menopausal women diminished estrogen can effect the function of any layer of the artery. Estrogen administration promotes vasodilation in part by stimulating prostacyclin and nitric oxide synthesis.

17-beta estradiol is a natural agonist/binder for estrogen receptors alpha and beta. Genistein a soy derived phytoestrogen also binds to estrogen receptors alpha and beta.

Sources:

Mechanism of Estrogenic Vascular Protection
Jayachandran & Miller MD’s
Am J Physiol Heart Circ 2006

The Vascular Protective Effects of Estrogen
Farhat, Lavigne, Ramwell MD’s
The FASEB Journal Vol 10, 615-624

Aging Hearts & Arteries
National Institutes of Health April 2005

Estrogen Effects Blood Vessel Tone

Estrogen directly regulates vasomotor tone through both short-term and long-term effects on blood vessels. Long term administration of estrogen is associated with deceased plasma concentrations of renin, angiotensin converting enzyme, endothelin-1 and decreased vascular expression of the gene for angiotensin II receptor type, as well as an increased ratio of nitric oxide to endothelin-1 in the blood.  The net effect of these changes due to estrogen is to promote vasodilation: wide blood vessels.

Renin is an enzyme released by the kidney. Renin acts to raise blood pressure by activating angiotensin. Angiotensin-converting enzyme causes the conversion of angiotensin I to angiotensin II. Angiotensin II causes contraction of the smooth muscle in the blood vessels which raises blood pressure.

Angiotensin ll acts on the adrenal cortex to release aldosterone, which causes the kidneys to increase sodium and water retention. Diminished urinary output causes increased blood volume.  The greater the blood volume the harder the heart has to work to send blood to organs and cells.

Endothelin 1 is a molecule that causes changes in blood vessels and helps regulate blood pressure. Endothelin 1 is produced in a variety of tissues including endothelial and vascular smooth-muscle cells, neurons and the central nervous system, and endometrial cells.

Alterations in estrogen levels (receptor activity) has potential to effect any of these mechanisms and helps explain why the incidence of cardiovascular diseases is low in premenopausal women, rises in postmenopausal women and is reduced to premenopausal levels in postmenopausal women who receive estrogen therapy.

Source:
The Protective Effects of Estrogen on the Cardiovascular System
Michael Mendelsohn MD
Vol 340: 1901-1811 June 10,1999

Red Wine . . . Supple Arteries

Studies have shown that healthy people with the stiffest blood vessels were three times more apt to develop high blood pressure over a five year span than those with supple, pliable vessels.

In a large scale study involving 3,075 healthy older people, those who had the highest pulse wave velocity (PWV) a measure of arterial stiffness, were three times more likely to die of cardiovascular disease than those who had the lowest PWV.

The well being of your arteries depends on a healthy endothelium, the inner lining of your blood vessels. Endothelial cells control almost every activity that occurs in the blood vessels.

Healthy endothelial cells produce nitric oxide, an important signaling molecule that helps keep arteries supple. When nitric oxide enters a cell it stimulates a biochemical process that relaxes and dilates blood vessels. Nitric oxide also helps keep arteries flowing freely by preventing platelets and white blood cells from sticking to the blood vessel wall.

Smoking 1 cigarette causes a significant impairment in endothelial function.
Red wine's antioxidant substances enhance production of nitric oxide.

"People who maintain a healthy endothelium as they get older and those who make an effort to do things that promote the repair of injured endothelium can reduce the risk of heart attacks and strokes caused by atherosclerosis or hypertension" (Edward Lakatta MD, National Institute on Aging USA).

Sources:
Aging Hearts & Arteries
National Institutes of Health USA 2005

J Am Coll Cardiology.
Red wine increases the expression of human endothelial nitric oxide synthase:
a mechanism that may contribute to its beneficial cardiovascular effects.
Wallerath T, Poleo D, Li H, Förstermann U. 2003 Feb 5;41(3):479-81.

Stress Affects Blood Vessels

Emotional stress triggers the release of adrenaline from the adrenal glands and noradrenaline from the nerve endings of the heart and blood vessels. These hormones make the heart beat faster (increase heart rate & contractility) and adversely affect blood vessels. Under stress, an older person’s blood pressure rises more rapidly and stays higher longer than a younger person’s because the older person’s blood vessels are stiffer and have lost much of their elasticity.

Researchers have found that stress reduction techniques, such as taking a walk, practicing yoga or deep breathing are important to cardiovascular health.

Source:
Aging Hearts & Arteries
National institutes of Health
US Dept of Health & Human Services. April 2005