The Mayo Clinic explained in their Aug. 1, 2006 online article "Drugs and Supplements: Vitamin D," available on their website:
"Vitamin D is found in numerous dietary sources such as fish, eggs, fortified milk, and cod liver oil. The sun is also a significant contributor to our daily production of vitamin D, and as little as 10 minutes of exposure is thought to be enough to prevent deficiencies...
The major biological function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. Recently, research also suggests vitamin D may provide protection from osteoporosis, hypertension, cancer, and several autoimmune diseases...
Adequate Intake (AI) levels have established by the U.S. Institute of Medicine of the National Academy of Sciences to prevent deficiencies in vitamin D. The AI is 5 micrograms (200 IU [International Units]) daily for all individuals (males, female, pregnant/lactating women) under the age of 50 years-old, 10 micrograms daily (400 IU) for all individuals from 50-70 years-old, and 15 micrograms daily (600 IU) for those who are over the age of 70 years-old. The daily upper limit for vitamin D is 25 micrograms (1,000 IU) for infants up to 12 months of age and 50 micrograms (2,000 IU) for children, adults, pregnant and lactating women due to toxicities that can occur when taken in higher doses."
Is Drinking Milk a Good Way to Get the Recommended Daily Amount of Vitamin D?
The National Institutes of Health Office of Dietary Supplements provided the following description in the Aug. 5, 2005 document "Dietary Supplement Fact Sheet: Vitamin D," available on the Office's website:
"About 98% to 99% of the milk supply in the U.S. is fortified with 10 micrograms (µg) (equal to 400 International Units or IU) of vitamin D per quart. One cup of vitamin D fortified milk supplies one-half [50%] of the recommended daily intake [Daily Value] for adults between the ages of 19 and 50, one-fourth [25%] of the recommended daily intake for adults between the ages of 51 and 70, and approximately 15% of the recommended daily intake for adults age 71 and over...
A food that provides 10-19% of the DV [Daily Value] is a good source and a food that provides 20% or more of the DV is high in that nutrient."
The National Dairy Council reported in its 2000 report Newer Knowledge of Dairy Foods, available on the organization's website:
"Vitamin D-fortified milk is the primary food source of vitamin D in the U.S. This vitamin plays an important role in calcium absorption and metabolism. Two 8-ounce servings of vitamin-D fortified milk provide the amount of vitamin D currently recommended for children of all ages (200 IU/day)...
Without consuming dairy foods, it is difficult for adolescents to meet recommended intakes of calcium and vitamin D...
Vitamin D-fortified milk helps adults, particularly older adults, meet their need for vitamin D... Vitamin D-fortified milk contains 400 IU (10 µg) of vitamin D per quart."
Neal Barnard, MD, President of the Physicians Committee for Responsible Medicine, explained in an Apr. 4, 2001 news release titled "Cow's Milk a Risky Approach to Rickets, Advise Doctors and Dietitians," available on the PCRM website:
"Milk is the least healthy source of
vitamin D. Rather, we should encourage increased outdoor activity,
which would not only help children produce enough vitamin D naturally,
but would help strengthen their bones, improve fitness, and reduce
obesity. For kids who do not get enough sunlight, any typical
multivitamin will do the job."
Edward Giovannucci, MD, Professor of Nutrition and Epidemiology at Harvard University explained in his 2006 article "Ask the Expert: Vitamin D and Chronic Disease Prevention," available on the website of the Harvard School of Public Health:
"Several randomized trials found that individuals who received 800 IU per day of vitamin D lowered their risk of osteoporosis; trials that provided only 400 IU per day did not show this benefit. It is reasonable to postulate that more than 800 IU per day would provide even more benefit, but this is not proven...
Milk alone is unlikely to be an adequate source of vitamin D. True, milk is fortified in the U.S. (it is not fortified in most countries). Each glass of fortified milk should contain about 100 IU of vitamin D (but on average, it may contain only 50 IU). So someone would have to drink at least 8 glasses of milk per day to get 800 IU of vitamin D. Moreover, most experts now conclude that 1,000 to 2,000 IU per day of vitamin D may be what we need for optimum health."