To take or not to take vitamins, the answer to that question seems to depend on the latest study and who you ask. We are told by many experts to get our vitamins from food rather than mega-doses of supplements. Others tell us that our food is not fresh, we eat the wrong things and to stay healthy we need to take supplements.
But even with the “right” nutrition, it turns out that many of us are lacking Vitamin D, and this can have some extremely serious health consequences. Dr. Judith Reichman, TODAY medical contributor, how to get a better drade in "D”:
What does “D” do?
This is, quite frankly, an amazing vitamin that may have been undervalued. Most of us (physicians included), thought we just needed “some” to prevent rickets and bone deformities; and that once our food (milk and cereal) was fortified with D we didn’t have to worry, at least when it came to our kids. We have acknowledged that Vitamin D is a bone vitamin; it plays a role in calcium absorption and bone metabolism. Indeed, without D only 10 to 15% of dietary calcium is absorbed whereas adequate amounts of D can more than double calcium absorption. And we all know we need calcium to fight the development of osteoporosis. In its bone building capacity, Vitamin D also prevents over production of hormone from the parathyroid glands which when too high can “leach” calcium from the bones. But did you know that D’s affect on bones starts in the womb: If a pregnant woman is D deficient, her developing fetus may suffer from growth retardation and (especially if the baby breastfeeds and doesn’t get additional D) then become high risk for fractures and later age osteoporosis.
D is much more than a bone vitamin. It is crucial to many of our tissues and organs; these include the brain, prostate, breast, colon, heart, lung and muscle as well as our immune cells. Vitamin D controls more than 200 genes that go on to direct cellular processes such as division, growth, development, blood supply and degeneration. It can make normal cells grow and abnormal ones (cancer cells) die. It also helps immune cells destroy certain infectious agents, such as TB.
How do we get our D?
Three ways: Exposure to sunlight, through food and taking supplements:
Sun: Ultraviolet B waves penetrate skin and convert a type of cholesterol in the skin to D (D3).
Diet: D is present or fortified in some (relatively few) foods. It’s contained in oily fish (salmon, mackerel, sardines), and fortified milk (one glass has 400 units). There is very little in breast milk.
Supplements: Over the counter vitamin D comes in the form of D2 or D3. Prescription Vitamin D is D2 (D2 is 30% as active as D3).
Vitamin D from all these sources is metabolized in the liver to 25-hydroxy Vitamin D. This is the form of D that is measured in blood tests, but to be active, enter the cells and attach to receptors this D has to be further metabolized by the kidneys and other tissues to 1, 25-dihydroxy Vitamin D (in case you must know the official name).
Know your D levels
- You are considered Vitamin D deficient if your blood level is less than 20 nanograms per milliliter (ng/ml).
- You are low or have relative insufficiency of Vitamin D between 21 and 29 ng/ml.
- You have sufficient D if the level is 30 or greater.
Based on these levels, estimates are that one billion people worldwide have Vitamin D deficiency or insufficiency.
Why are so many of us D deficient?
Let’s start with newborns. Breastfeeding is, without doubt, the healthiest way to feed a baby. Pediatricians currently recommend that breast milk be used as the sole nutrition for the first six months of life and then continued to one year of age. But unfortunately, breast milk contains very little Vitamin D, especially if mom is not “super-sizing” her intake or sun absorption of D. Even if mom takes a multi-vitamin with 400 international units (IU) of D or drinks milk (2-3 glasses a day), studies have shown that the majority of infants are still not getting enough D. Hence, it’s recommended that breast fed infants be given supplements of at least 400 units of D a day, although many pediatricians feel 1000 to 2000 units are appropriate.
Toddlers and children often don’t get their “sunlight D” because they are told to play outside when peak sun hours have passed. If they are out between 10AM and 3PM, they are covered up with clothes and sunscreen which prevents UVB rays from penetrating their skin. This cautionary behavior obviously prevents sunburns that, at an early age, are known to cause malignant melanoma.
And then added to the “low D issue” is the fact that so many children are spending countless hours indoors watching TV and computer screens when not in school. Children who live in the inner city are not getting much sunlight at any time of day and are especially vulnerable to lack of D. And finally, children with dark skin have less absorption of UVB radiation when their skin is exposed.
Adults: Winter and the diminution of UVB rays from the sun causes D deprivation in both children and adults, especially if they live at latitudes that are greater than 35 degrees from the equator.
The elderly: Age is a D detriment, since in the “growing older” population the kidneys are less capable of converting Vitamin D to its biologically active form.
Studies have shown that up to 50% of girls and adolescent females are D deficient, especially if they are black or Hispanic. Individuals of any ethnic group tested at the end of winter are more likely to have low D levels. One study found that 32% of healthy students, physicians and residents working at a Boston hospital (who drank milk and took a daily multi-vitamin) had low levels of D. The higher the latitude, i.e. the further from the equator, the more likely a population will be sun deprived and low in D. However, even in “sunny- near-the–equator” countries, where clothes are worn to shield most of the skin for religious, political or health concerns (examples: Saudi Arabia, Australia, Turkey, and India) Vitamin D deficiency is common. Indeed it’s been found to occur in 20 to 50% of the children and adults.
Pregnant and lactating women are also at considerable risk for low D, even if they take “regular” prenatal vitamins, eat fish or drink milk. One study found 73% of the women and 80% of their infants were deficient in Vitamin D at the time of birth.
Obese individuals store Vitamin D in their fat cells where it becomes less available to other tissues and hence may result in a relative lack of available D.
What are the consequences of “national and global” Vitamin D deficiency?
- In Pregnancy: fetal growth problems for the fetus
- Childhood: Lack of calcium in the skeleton (if very low, rickets; if insufficient, future low bone mass and osteoporosis).
- Adults: Osteomalacia (soft bone and bone pain) Note: This may cause chest pain and bone pain in individuals diagnosed with fibromyalgia, chronic fatigue and even depression.
- Osteoporosis: 47% of women and 22% of men over the age of 50 will have an osteoporotic fracture in their lifetime. Adding 800 units of D3 daily for 3 years together with 1200 milligrams of calcium decreases fracture rates by as much as 26% (but if calcium is given with less D, there is little or no improvement).
Hodgkin’s Lymphoma: People living at higher latitudes (with less UVB radiation from the sun) are at increased risk for this type of cancer as well as prostate, ovarian and breast cancer. Blood levels of 25-hydroxy vitamin D below 20ng/ml are associated with a 30-50% increased risk of these cancers and higher mortality. (The Nurses’ Study of 32,826 women showed that increasing Vitamin D to 39.9 ng/ml decreased the risk of developing colon/rectal cancer by 50% and conversely, if they had very low D (less than 12ng/ml), their risk for this cancer increased 253% during 8 years of follow-up. Studies have also suggested similar decreased risk of breast cancer in women with high D levels.
Diabetes: Living at higher latitudes increases the risk of Type 1 diabetes. In a study from Finland of over 10,000 children, adding Vitamin D during pregnancy together with 2000 units daily during the first year of life decreased the risk of Type 1 diabetes by 80% over 31-years of follow-up. Another study has shown that combining daily doses of 1200 milligrams of calcium and 800 units of D decreased the risk of Type 2 diabetes by 33%.
Cardio-vascular disease: Again, living at higher latitudes has been linked to an increased risk of hypertension and diabetes. Is this also due to D deficiency? ...Perhaps to some extent; one study showed that when hypertensive individuals were exposed to ultraviolet B radiation three times a week for 3 months, their blood pressure went down. (If you are hypertensive don’t go off your medication and try this on your own!)
Schizophrenia and depression: An association of low D has been shown. Perhaps D in the womb is important for brain development and functions later in life.
Muscle weakness: Skeletal muscles require D for maximum function. Increased D levels have been shown to improve performance, speed and strength of certain muscles. Supplementing 800 units daily also helps the elderly maintain their balance. (Nursing home residents decrease their falls on 800 units of D and 1200 mg of calcium, but not when they receive only 400 units of D with the calcium).
Immune reaction: When blood levels of Vitamin D are under 20ng/ml certain immune reactions just don’t happen. (This gives credence to a theory that Vitamin D deficiency increases risk of tuberculosis in black Americans who are more likely to have D deficiencies because of the pigmentation of their skin and their diminished absorption of UVB rays.)
How Do We Get Our D?
Natural sources Vitamin D Content
Salmon, fresh/wild 3.5 ounces 600-1000 units of D
Fresh farmed salmon 3.5 ounces 100-250 IUs of D
Canned salmon (3.5 ounces) 300-600 IUs of D
Sardines, canned (3.5 ounces) About 300 IUs of
Tuna, canned (3.6 ounces) 230 IUs of Vitamin D
Cod liver oil (1 teaspoon) 400-1000 of Vitamin D
Egg yolk About 200 IU’s of Vitamin D
Fortified milk About 100 units/8 ounces Vitamin D
Fortified orange juice About 100 units/8 ounces Vitamin D
Fortified breakfast cereals About 100 IUs/serving, Vitamin D
Prescription Vitamin D2, 50,000 units/capsule
Over the counter multi-vitamin 400 IUs (usually D3)
Vitamin D3 400, 800, 1000 and 2000 units
How Much Should We Get?
Although the RDA (recommended daily amount) is only 400 IUs for adults and 600 for those over seventy, this may not suffice to prevent a Vitamin D deficiency.
Prevention of Vitamin D Deficiency
Group Prevention Measures
Breastfeeding infants 400 units of D3 daily
1000-4000 units of D/day is safe
Children with inadequate sun exposure or dark skin 400-1000 units of Vitamin D, Sensible sun exposure
Adults with inadequate sun exposure/over 50 Supplementation with 800-1000 units of D3/day or
Or over 50 50,000 units of D2 every 2 to 2 weeks, Sensible sun exposure
Pregnant or lactating women 1000-2000 units of Vitamin D3/day, 50,000 units of D2 every 2 or weeks
Obesity 1000-2000 units of D3 a day or 50,000 units of D2 every 1, 2 or 4 Weeks
(Condensed from the New England Journal of Medicine - 353:3)
What is Sensible Sun Exposure?
5 to 10 minutes of direct sunlight between 10AM and 3PM (depending on the season, latitude and skin sensitivity) on the arms and legs without sunblock. This gives the equivalent of up to 3000 Units D which is stored in body fat and released over time.
Should We All Get Our Vitamin D Level’s Checked?
It’s expensive; and the current recommendation is simply to assume that your level will be okay if you consume proper amounts of D or get it through sun exposure. I have, however started to check some of my patients who have low bone density or whom I feel are “at risk”. I council them on the need for supplemental doses of D and/or limited sun exposure. I did check my own Vitamin D level and was relieved to see that it was an adequate 32 ng/ml. (I have taken D with calcium for years).
After considering all the evidence, I also go outside on weekends (easy, I live in Southern California) for 10 minutes without smearing sunscreen on my arms and legs. This should keep me in good “D stead”.
Dr. Judith Reichman, the TODAY show’s medical contributor on women’s health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, “Slow Your Clock Down: The Complete Guide to a Healthy, Younger You,” which is now available in paperback. It is published by William Morrow, a division of .
PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.