December 2011 
Nearly 40 percent of adults in the U.S. take a multivitamin to ensure good health. A recent study of women in Iowa suggests that this daily habit may be doing more harm than good. A closer look, however, reveals major flaws in the study--and offers reassurance that taking a daily multivitamin may still be a smart move. Read more
5 Quick Tips: Getting the right vitamins
1. Eat a healthy diet. A multivitamin provides some insurance against deficiencies but is far less important for health than the healthy food patterns described on this website. Choose a diet rich in fruits, vegetables, whole grains, nuts and healthy oils, and low in red meat and unhealthy fats--let the Healthy Eating Pyramid and Healthy Eating Plate be your guides.
2. Choose a daily multivitamin. A daily multivitamin is an inexpensive nutrition insurance policy, and for most people, the benefits seem to outweigh the risks. Try to take one every day.
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Low Vitamin D: A Global Concern
The Institute of Medicine's (IOM) recommended daily intake of vitamin D is 600 IU for people ages 1 to 70, and 800 IU after age 70. (7) Yet this is overly conservative, since the best available evidence shows optimal intakes are higher, at least 800–1,000 IU for adults.
In extremely high doses—hundreds of thousands of IU or more—vitamin D is toxic and can even cause death. But in children over the age of 9 and in adults, taking up to 4,000 IU per day as a supplement is safe; ages 4 to 8, up to 3,000 IU; ages 1 to 3, 2,500 IU; ages 6 to 12 months, up to 1,500 IU; and ages 0 to 6 months, up to 1,000 IU. (7)
Many people may need 2,000 IU per day (or more) for adequate blood levels, particularly if they have darker skin, spend winters at higher latitudes (such as the northern U.S.), or spend little time in the sun. If you fall into one of these groups, which would include most of the U.S. population, taking 2,000 IU is reasonable and well within the safe range for adults. As always, it's a good idea to discuss use of supplements with your doctor, and he or she may want to order a vitamin D blood test.
To prevent rickets, the American Academy of Pediatrics recommends vitamin D supplements of 400 IU per day for breastfed infants, and also for non-breastfed infants and children who do not drink at least a liter of vitamin D fortified milk each day. (6) Infants and children at high risk of deficiency—those who are born premature, have dark skin, or live at high latitudes—may need supplements of up to 800 IU per day, especially in the winter.
If you live north of the line connecting San Francisco to Philadelphia and Athens to Beijing, odds are that you don't get enough vitamin D. The same holds true if you don't get outside for at least a 15-minute daily walk in the sun. African-Americans and others with dark skin, as well as older individuals, tend to have much lower levels of vitamin D, as do people who are overweight or obese.
Worldwide, inadequate vitamin D is common, and deficiencies can be found on all continents, in all ethnic groups, and across all ages. Some surveys suggest that perhaps half of the world’s population has inadequate blood levels of vitamin D. (1-3) Indeed, in industrialized countries, doctors are even seeing the resurgence of rickets, the bone-weakening disease that had been largely eradicated through vitamin D fortification. (4-6)
Why are these widespread low levels of vitamin D such a great concern? Because research conducted over the past decade suggests that vitamin D plays a much broader disease-fighting role than once thought.
Being “D-ficient” may increase the risk of a host of chronic diseases, such as osteoporosis, heart disease, some cancers, and multiple sclerosis, as well as infectious diseases, such as tuberculosis and even the seasonal flu.
Currently, there’s scientific debate about how much vitamin D people need each day. The Institute of Medicine (IOM), in a long-awaited report released in November 2010 recommends increasing the daily vitamin D intake for children and adults in the U.S. and Canada, to 600 IU per day for people ages 1 to 70, and 800 IU for people over age 70. (7) The report also recognized the safety of vitamin D by increasing the upper limit from 2,000 to 4,000 IU per day, and acknowledged that even at 4,000 IU per day, there was no good evidence of harm.
The new guidelines, however, are overly conservative about the recommended intake, and they do not give enough weight to some of the latest science on vitamin D and health. For bone health and chronic disease prevention, many people are likely to need more vitamin D than even these new government guidelines recommend.
4. Say no to "megas." In general, avoid mega-dose vitamins and mega-fortified foods. Vitamin D is an exception, as many people need more than the Recommended Dietary Allowance (RDA). A standard multivitamin also has a day's worth of folic acid, so if you are taking a daily multivitamin you should avoid foods that have high amounts of folic acid added to them.
5. Avoid "super" supplements. Don't be swayed by the wild health claims of the many health supplements advertised on TV and the Internet. If they sound too good to be true, you can be sure they are.
About HSPH
Mission & Objectives
The overarching mission of the Harvard School of Public Health is to advance the public’s health through learning, discovery, and communication.
To pursue this mission, the School produces knowledge through research, reproduces knowledge through higher education, and translates knowledge into evidence that can be communicated to the public, policy makers, and practitioners to advance the health of populations.
Our objectives are:
• to provide the highest level of education to public health scientists, practitioners, and leaders
• to foster new discoveries leading to improved health for the people of this country and all nations
• to strengthen health capacities and services for communities
• to inform policy debate, disseminate health information, and increase awareness of health as a public good and fundamental right.
The field of public health is inherently multi-disciplinary. So, too, are the interests and expertise of the School’s faculty and students, which extend across the biological, quantitative, and social sciences. With our roots in the basic sciences, we are able to confront the most pressing diseases of our time—AIDS, cancer, and heart disease—by adding to our knowledge of the biological, chemical, genetic, and societal forces underlying disease. Core quantitative disciplines like epidemiology and biostatistics are fundamental to analyzing the broad impact of health problems, allowing us to look beyond individuals to entire populations. And, because preventing disease is at the heart of public health, we also pursue the social sciences to better understand societal influences of health-related behaviors and to inform public policy—both of which are critical elements to educating and empowering people to lead healthier lives.
From advancing scientific discovery to educating national and international leaders, the Harvard School of Public Health has been at the forefront of efforts to benefit the health of populations worldwide. Shaping new ideas in our field and communicating them effectively will continue to be priorities in the years ahead as we serve society’s changing health needs.
