Vitamin Deficiencies Causing Bruises

Woman with bruised knee at doctor's office.
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Bruising is a common condition that affects everyone, although it rarely requires medical attention. While naturally clumsy people have more accidents and acquire more bruises, often there is an underlying issue that causes bruising, such as fragile capillaries, thin skin, lack of collagen and coagulation problems. Many of these underlying conditions are associated with vitamin deficiencies.


Bruises are usually caused by blunt trauma that ruptures the tiny capillaries under the skin and allows small amounts of blood to seep out, leaving the area darkened. The changing color of a bruise over time is related to the break-down of blood. Fresh bruises are usually dark purple in color, whereas a week-old bruise is often yellowish. According to "Advanced Nutrition: Macronutrients, Micronutrients and Metabolism," research has shown that the leading cause of frequent bruising is a deficiency in one or more nutrients. The elderly, due to their comparatively poor diet, thin skin, weak blood vessels and blood thinning medications, are especially susceptible to bruising.

Vitamin C Deficiency

Vitamin C, or ascorbic acid, is a widely required nutrient in the body for collagen production, immune boosting and antioxidant activity. Collagen is necessary for connective tissue maintenance and repair, especially for the walls of blood vessels. Vitamin C is also a powerful antioxidant that eliminates harmful free-radicals, which are thought to be responsible for aging and degeneration of tissues, including blood vessels. Mild vitamin C deficiency leads to frequent bruising, joint pain, reduced immunity and increased risks of cardiovascular diseases, according to "Human Biochemistry and Disease." Severe deficiency, termed scurvy, also includes bleeding gums, blood vessel deterioration, hair, fingernail and tooth loss, and ultimately, heart failure. The recommended daily allowance of vitamin C for adults ranges from 75 to 125 mg, depending on gender, pregnancy and breast-feeding, and cigarette smoking.

Vitamin K Deficiency

Vitamin K is required as a cofactor for an enzyme that is essential for the coagulation cascade to occur. Coagulation is a process of stopping blood flow by forming clots, which is critical for healing injuries. Vitamin K deficiency leads to uncontrollable bleeding and large bruises if capillaries are weak or damaged. According to "Vitamins: Fundamental Aspects in Nutrition and Health," vitamin K deficiency is more common in children, but does occur in adults who take anticoagulant drugs, mega-dose vitamin E supplements, drink large amounts of alcohol, and those who have liver diseases and fat absorption problems. In addition to excessive bruising, deficiency also leads to increased clotting time, nosebleeds, bleeding gums, blood in urine and feces and heavy menstruation. The RDA for vitamin K for adults ranges from 90 to 120 mg, depending on gender.

Vitamin B-9 and B-12 Deficiencies

Although not as common as vitamin C and K deficiencies, lack of B-9, or folic acid, and B-12 also leads to inappropriate bruising. According to "Nutrition Management and Restorative Dining for Older Adults," B-9 and B-12 deficiencies lead to elevated levels of homocysteine in the blood, which damages the walls of blood vessels and impairs DNA repair. Damaged blood vessels increase the risks of blood seepage. The RDA for B-9 ranges from 150 micrograms for infants, to 600 micrograms for pregnant females. The RDA for B-12 ranges from 0.4 micrograms for infants, to 2.8 micrograms for lactating females.