Breast Health Challenge Tip #3

Vitamin D and Breast Cancer

Vitamin D deficiency is common in at least 60% of women. It is estimated that raising the minimum year-round serum 25(OH)D level to 40 to 60 ng/mL (100-150 nmol/L) would prevent approximately 58,000 new cases of breast cancer and 49,000 new cases of colorectal cancer each year, and three fourths of deaths from these diseases in the United States and Canada. 2000 IU per day of vitamin D(3) taken daily is safe, and often more is needed to achieve ideal blood levels. I find that many women need 5,000-10,000 IUs of vitamin D3 daily.

Joint pain in postmenopausal women taking aromatase inhibitors is significantly decreased when women take 50,000 IU of vitamin D per week, with no harmful side effects. 25(OH)D levels ideally should be above 66 ng/ml (150 nmol/L) to achieve this result.

Sun Exposure Reduces Breast Cancer Risk

Vitamin D is produced in the skin on exposure to sunlight – specifically UV-B rays. Your skin uses sunlight to make 25-hydroxyvitamin D, or vitamin D3. Known as the sunshine vitamin, it reduces risk of breast and colon cancer when our levels are adequate. Time spent outdoors is associated with reduced breast cancer risk during all phases of our lives. How much sun exposure is needed? Only 5-10 minutes of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week.

Be careful in the sun – UV-B rays are also the primary cause of sunburn. Unfortunately sun tan lotion blocks UV-B penetration into your skin dramatically or completely, so you will not convert sunlight into D3 if you are wearing sun block. Window glass also blocks UV light, so if you spend most of your days indoors, you will be deficient in vitamin D.

Your Sun Exposure Prescription

Most of us depend on sun exposure to satisfy our requirements for vitamin D. Season, latitude, clouds, pollution, altitude, time of day, skin pigmentation, aging, sunscreen use, and glass all influence the skin production of vitamin D3. Once formed, vitamin D3 is metabolized in the liver and then in the kidney to its biologically active form, 1,25-dihydroxyvitamin D3. Vitamin D deficiency is an unrecognized epidemic among both children and adults in Canada and the United States. Vitamin D deficiency has been associated with osteoporosis in adults and increased risks of deadly cancers, cardiovascular disease, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes mellitus. Sensible sun exposure (usually 5-10 min of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency.

What Type of Vitamin D Supplementation is Best? 

Vitamin D comes in two forms – the preferred form, known as vitamin D3 (cholecalciferol), is derived from fish oil; and vitamin D2 (ergocalciferol) is found in plants and activated through irradiation. Vitamin D3 is found in eggs, organ meats, animal fat, cod liver oil and fish, and is the more effective form. Vegetarians such as myself are at a disadvantage, as vitamin D2 is less biologically active and can be toxic at high dosages. Therefore, it is advisable for vegetarians to supplement with Vitamin D3.