How Much Vitamin D? Tips to Get the Right Amount

My Diet Matters
too much vitamin D getting the right amount

As supplement sales go, vitamin D is one of the more popular supplements. Normal bone development in kids and bone maintenance in adults depend on this fat-soluble vitamin. Vitamin D helps with bone health and osteoporosis prevention by increasing absorption of other critical nutrients for bone strength- namely calcium, magnesium, and phosphate. So, while a shortage of this nutrient can hurt our health, what happens if you take too much? Unfortunately, as more people take this nutrient in pill form, there is the likelihood of taking too much vitamin D. Often people think that “if some is good, more may be better.” But, for supplements, this thinking is false. Many nutrients have an upper limit for safety. Therefore, knowing your individual needs before swallowing a lot of this supplement would be wise! 

Too much vitamin D or too little matters 

Beyond bones, vitamin D can affect other areas of the body. Strong research suggests that having too little in the body can cause a host of problems. These problems range from heart disease, depression, cancer, infections, and autoimmune disease. In addition to these conditions, some preliminary research is studying the correlation of low vitamin D levels and severity of COVID-19 symptoms. As we have vitamin D receptors everywhere in the body, the impact on health is potentially huge.

But what happens if too much is present in the body? Large amounts of supplemental vitamin D can cause constipation, headaches, weakness, confusion, and elevated blood calcium levels. As blood calcium levels rise, that calcium will deposit itself in the soft tissues such as the kidneys and heart. With time, the function of these organs will decline, and death can result. 

Vitamin D doubles as a hormone 

Vitamin D is dubbed the “sunshine” vitamin because our bodies make it from sun exposure. And, because our bodies make it, it is also called a hormone. For most people worldwide, sunlight supplies much of the necessary vitamin D. Human skin has a cholesterol compound that is activated by ultraviolet rays. When those UV rays hit bare skin, the body begins the process of making vitamin D. Over the next few days, the body continues the process of making the vitamin D active and available to the body with the help of the liver and kidneys. 

Our bodies are efficient “machines” that easily make enough vitamin D. Additionally, the human body will not make excessive amounts of this vitamin even if in the sun excessively. Efficient, right? But, if concerned about skin cancers, wrinkles, and sunburn, then too much sun is clearly a problem. Therein lies the problem-balancing our sunshine needs with our skin protection needs. 

Using the sun to help meet needs 

how much vitamin D

With many of us using sunscreen for cancer and wrinkle protection, how much sun exposure are we talking about? Fifteen minutes of sun exposure to bare skin a few times weekly is thought to be sufficient. You do not need to be in a bikini to make vitamin D. In fact, any skin can be exposed, including hands, arms, and face. With that said, there are so many modern factors that can potentially interfere with our bodies making enough of this nutrient. Some of the modern barriers to producing enough include: 

  • skin care products such as sunscreen and make-up with sunscreen
  • clothing
  • pollution
  • modern buildings
  • office environments for work
  • time of day exposed to sunshine
  • time of year (winter vs. summer)
  • geography
  • aging (older people have less ability to make vitamin D)
  • inadequate magnesium
  • weight status (obese people often have lower blood plasma levels)

Foods as a source of vitamin D 

Herein lies a problem that has led to more people taking supplements! There are not really a lot of foods that have vitamin D. This list is limited in terms of foods naturally rich in vitamin D and some of the foods listed below have been fortified. 

  • 566 IU from 3 oz. swordfish
  • 440 IU from 1 tsp. cod liver oil
  • 400 IU from 3 oz. salmon
  • 228 IU from 3 oz tuna
  • 137 IU from 1 cup vitamin D fortified orange juice
  • 120 IU from 1 cup fortified milk
  • 100 IU from 3/4 cup enriched cereals (where vitamin D has been added)
  • 40 IU from 1 egg

(Source: USDA Nutrient Data Base) 

If you are not eating the above foods, then your dietary vitamin D may be falling short of your requirements. If your sun exposure has not helped make sufficient vitamin D and your diet is limited in the above foods, then you may be a candidate for supplements. 

A note on requirements

The Recommended Daily Allowance (RDA) is 600 IUs for those aged 19-70. For those who are over 70, the recommendation is 800 IUs. However, these are not recommendations for those individuals that are deficient. For supplements, the better option is D3 as it is chemically like what is made by the body. Additionally, it may be more effective at raising blood levels. 

Know where you stand with blood testing 

how much vitamin D

If it seems even more confusing at this point to know if you need a supplement, I recommend getting your blood checked periodically. While many physicians feel comfortable recommending 1000-2000 IUs as a daily supplement, this does not seem prudent to me. There is really no reason to guess on how much vitamin D is right for you when blood work is accessible. Over the last decade, with the surge in testing, I have seen professional recommendations changing. Most basic lab work, when printed, will show a wide range of normal (30-100 ng/ml) as acceptable. And some labs show a normal range as being in the 20-100 ng/ml range. In my experience, many earlier research studies had suggested 45 ng/ml might be most desirable. Now, it would seem the desirable range has been tweaked down. 

A few more thoughts on blood levels

Some experts suggest 20-40 ng/ml is best, and others suggest 30-50 ng/ml. What’s clear to me is that the opinions vary and there will not be a set “ideal” value anytime soon. For those with blood work of less than 20 ng/ml, there is no question supplementation should be considered. For those over 50 ng/ml, if taking supplements, discontinuation might be in order. Other factors to consider include current symptoms and diseases, as well as personal and family medical history. For instance, a small group of fibromyalgia patients saw a decline in pain symptoms when blood levels increased to 32-48 ng/dl. If you do have medical conditions, it is best to discuss with a knowledgeable health care provider on what may be best for you personally.

Dosing tips to get to desired levels 

After you’ve had blood work to assess your levels, you can choose to supplement or not, depending on your results, lifestyle, and input from trusted health care provider. If results are too low, you can try more sunshine or attempt to add more vitamin D rich foods (which is a challenge). If moving forward with supplements, then you should do so systematically. In general, it is suggested that 100 IUs will increase levels 1 ng in several months. So, if you are at 20 ng and you want to get to 30 ng, then you must take 1000 IUs of supplemental vitamin D for a few months to move your blood levels higher. Once desired blood levels are achieved, most people can keep those blood levels with 1000 IUs or less through supplements and foods.

Other factors to consider 

foods with fats

Obese individuals. Obesity may dictate adjusted dosages for correcting deficiencies. In fact, obese individuals that are deficient may require twice as much supplemental vitamin D to correct the deficiency.

Skin color. According to some research, African Americans may not need as much vitamin D, at least for bone health. Darker skinned individuals also make less vitamin D when exposed to the sun. Clearly, more research is needed on subsets of the population and ideal blood levels.

Timing of supplements. Always try and take this supplement with fats or a meal. As a fat-soluble vitamin, the fats in your diet or your meal will enhance absorption. Visible fats such as oils and foods such as olives, seeds, and nuts can aid absorption of vitamin D.

Take away

Getting the right amount of vitamin D can be a challenge. Too little and too much are potentially problematic. While we can make this vitamin with sun exposure, many current lifestyle barriers exist that can prevent our bodies’ from doing so. And food sources are limited. Supplement use is booming for this nutrient. However, it should not be assumed that there is a set formula for how much of this supplement is safe. Blood testing is available for assessing needs, which varies based on many of the above factors. And, as always, a discussion with a knowledgeable and qualified health care provider for individual dosing if using vitamin D supplements is recommended!

Sue Rose, MS, RD, LDN

Sue Rose helps readers sort through the maze of nutrition information available to the public. As a seasoned clinical dietitian/nutritionist with decades of experience, her blogs attempt to educate and inform the public at a time when there is so much information it is often overwhelming to understand. Stay tuned for clarity on a variety of topics!

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Disclaimer

Use this information at your own risk. Although I am a licensed IL dietitian/nutritionist, I am not your dietitian. The information in my blog Chew on This located at www.mydietmatters.com is for educational and informational purposes only. It is also my own opinion and subject to change in the future. Please consult with your own medical professionals for individual treatment.