As many as 90% of Americans do not get enough vitamin D. Why the interest in this particular vitamin? First, it’s essential in maintaining calcium metabolism. Yet, it is rare and hard to absorb. It is naturally found in few foods, but is easily available via ultraviolet sun rays, and of course through supplements. However, the amount available in supplements is not enough for most people and taking too many supplements can have an adverse reaction on your body. Vitamin D helps support a healthy immune system – thus, more D, fewer colds and many other more serious illnesses. Vitamin D is essential for calcium absorption and for adequate bone growth. It is no surprise that pediatricians encourage kids to spend time outside – not just for play but also to get enough sunlight and vitamin D for growth.
What is so magical about vitamin D?
Research indicates that vitamin D plays a role in the prevention of colon, prostate, and breast cancers. A 2007 study in the “Archives of Internal Medicine” showed that higher vitamin D levels could be associated with lower mortality from life-threatening conditions including cancer, cardiovascular disease, and diabetes mellitus that account for up to 70% of total mortality in high-income countries. Moreover, research suggests that vitamin D might play some role in the prevention and treatment of type 1 and type 2 diabetes, high blood pressure, multiple sclerosis, and coronary disease. Exercise is another big contributor, since by reducing the amount of body fat and lowering your BMI, you can help vitamin D absorption. It is crucial for pregnant women to get enough vitamin D, since the presence or lack of it affects the baby’s budding brain. Early research suggests a possible link between children lacking vitamin D, at birth and in early childhood, and autism, however, results are yet inconclusive. One thing certain, vitamin D is a super-power that can profoundly affect our lives.
Where can you get vitamin D?
Sunlight is a great and free way to get your vitamin D exposure. However, many factors affect how much you can get – namely, season, location, time of day, clouds, smog and sunscreen. If you live in the southern states (or latitudes below 34 degrees north), you are naturally getting more vitamin D than your northern friends. There is less vitamin D in February-November, since the UV rays are weaker. Clouds and smog will block the absorption, as would any natural structures (sitting in a sunroom would not get you vitamin D, since windows block the rays). Finally, sunscreen can block the absorption of UV rays and thus vitamin D. In US alone, skin cancer due to UV radiation takes over 8000 lives each year, so sun protection is still vital to your health. It is a good idea to spend 5-15 minutes in the sun at least twice a week but still wearing sunscreen to protect your skin the rest of the time.
There are a few foods containing vitamin D. The highest amount of vitamin D is found is in fish, particularly salmon, mackerel, tuna, cod, herring, eel and sardines. Fortified milk and orange juice are another excellent source. Other nature wonders full of vitamin D are mushrooms, liver, cheese, and eggs (yolk is where you will find D).
Vitamin D is also available in supplements – D2 (ergocalciferol) and D3 (cholecalciferol). The latter has been found to be slightly more effective. Beware not to use too much, since it can be toxic and lead to nausea, vomiting, poor appetite, constipation, weakness, and weight loss. It can also lead to confusion and heart rhythm abnormalities in extreme quantities.
What are the risks if you don’t get enough D?
In extreme cases, lack of vitamin D causes osteomalacia, a bone loss disease in adults, and rickets, a disease characterized by a failure of bone tissue to properly mineralize, resulting in soft bones and skeletal deformities in children. Osteoporosis is another example of a long-term calcium and vitamin D deficiency, and over 25 million people suffer from it in the US alone. Those not getting enough vitamin D through foods or sunlight are at risk, but in particular:
- Exclusively and partially breastfed babies that are not getting the vitamin D supplement (they need an additional 400 IU per day). Most commercial formulas contain the needed amount of vitamin D. So our suggestion is to either supplement breastfeeding with formula or with a vitamin D supplement.
- People with limited sun exposure and dark skin. The ability to absorb the adequate amount of sunlight is lower in those living in northern latitudes or with higher melanin pigment
- Older adults. Aging skin cannot synthesize vitamin D as efficiently and the kidney is worse at converting vitamin D to its active hormone form.
- Overweight people. Those with a BMI over 30, produce more body fat and fat can block the absorption of vitamin D.
How much vitamin D do you need?
An average daily intake of 1700 IU has been a suggested amount in a lot of research. Note that it’s easiest to get most of it from sunlight vs. foods or supplements.
The amount is very personal, since how much vitamin D you need varies with age, body weight, percent of body fat, latitude, skin coloration, season of the year, use of sunblock, sun exposure and your overall health status. Those who need to make a conscious effort to use more vitamin D include older people, taller and heavier people, those living in northern areas, dark-skinned people. If you use sunblock, that’s great in preventing skin cancers, but try to spend some minimal time (as little as 5 minutes) in the sun without it. More specifically…
Healthy children under the age of 2 years should take 1,000 IU per day – over the age of 2, 2,000 IU per day.
Well adults and adolescents between 80-130 pounds should start with 3,000 IU per day while those at 130-170 pounds should take 4,000 IU per day. Those over 170 pounds should receive 5,000 IU per day.
