The Best Vitamin D Supplement
To find our top picks, we consulted doctors and nutritionists from across the country, read through hundreds of ingredients labels, and utilized the results from three different independent lab tests. In the end, we found two supplements that stand the best chance of boosting your vitamin D levels.
How we chose the best vitamin D supplement
Vitamin D3 is better than vitamin D2
In our search for the best vitamin D supplement, we learned that there are actually two types of vitamin D: D2 (ergocalciferol), which comes from plants, and D3 (cholecalciferol), which is manufactured using fish oil or — more commonly — lanolin taken from sheep wool and subjected to ultraviolet (UV) radiation. UV radiation is what our bodies use to make natural vitamin D when our skin is exposed to sunlight. Most people should choose a supplement with vitamin D3, since it’s absorbed more easily than D2.
“D3 mimics the way our bodies make vitamin D from sunlight and it’s more easily absorbed, making it the best option for most people.”
Because vitamin D3 is more widely recommended and more available in stores, we cut any supplements that use D2.
The Food and Drug Administration (FDA) regulates food products, but not dietary supplements. So it’s anybody’s guess if what’s in a pill actually matches what’s on its bottle label. Product ingredients can vary widely, and some supplements even contain harmful lead or other contaminants. In fact, Labdoor, a reputable third-party testing company, found that the actual dosage of vitamin D supplements sometimes exceeded what was listed on the label by as much as 900 percent. That’s why we required all of our top picks to be vetted by at least one of three reputable, independent labs:
United States Pharmacopeial Convention (USP) – A scientific non-profit that sets standards for quality and purity in medicines and food supplements in the US and more than 140 other countries.
Labdoor – A free consumer resource that focuses on testing dietary supplements for purity, accuracy, and value.
National Sanitation Foundation (NSF) – An independent organization that sets worldwide standards for consumer product safety.
Ever wonder why vitamin D, like many supplements, contains glycerin, water, cellulose, or other fillers? We did too, so we asked Jamie Shuck, brand manager for Vitabiotics, one of the UK’s largest vitamin manufacturers. “Vitamin D is needed by the body only in tiny microgram amounts, which is barely a speck in its pure form — far smaller than a grain of rice and too small to even pick up,” Shuck explained. “Therefore, all vitamin D supplements must be formulated with other ingredients to increase the volume of the product, so customers are able to measure a safe and accurate dose.”
While it’s impossible to find a vitamin D supplement that contains just vitamin D, we did look for products that avoided questionable additives like sugar, flavoring, artificial color, and preservatives. We also chose products containing vitamin D with no other dietary supplements. According to the experts we talked to, almost everyone needs a vitamin D supplement, while only some of us need or want additional ingredients like calcium or CoQ10. Products with proprietary blends make it hard to know the specific dose of vitamin D, which as Dr Feuerstein pointed out, “makes it difficult to treat someone who has a vitamin D deficiency,” so we cut those too.
Like vitamins A, E, and K, vitamin D is fat-soluble, which means it dissolves in fat rather than water. That means vitamin D is best absorbed by the body when taken with fatty foods and is the reason many vitamin D supplements also contain an oil.
If you choose a supplement that doesn’t include oil, nutritionist Shereen Lehman recommends taking it with a little added fat. “You don’t need a lot,” she explains. “A salad with dressing, or a little cheese, avocado, or meat are good. Even seafood would have enough natural fat to help with vitamin D absorption.”
But we wanted to make it easy, so we cut any supplements that didn’t include some form of oil or fatty acid from olives, soybeans, or another healthy source.
The 2 best vitamin D supplements
- Kirkland Signature Extra Strength Vitamin D3 2000 IU –Best Value Pick
- Nature Made Vitamin D3 –Best Drugstore Pick
Why we chose it
We liked the short list of ingredients: 2,000 IU of vitamin D3 (as cholecalciferol, which mimics the way the body naturally processes vitamin D), soybean oil (rich in heart-healthy polyunsaturated fats), plus gelatin, glycerin, and water for the softgel capsule. Kirkland Signature even earned kudos from not one, but two independent labs. Its label bears the USP symbol, arguably the gold standard for product testing. USP certification is recognized around the world.
At about $0.01 per serving, it’s less than half the cost of our other top pick. We loved the Costco-sized bottle, which contained 600 softgels that were as small as any we tested. After all, if you’re going to make vitamin D supplements a part of your daily routine, you might as well make it easy on yourself: one tiny pill that’s easy to swallow, in a bottle that will last for a good 20 months. At $3.50 per year, Kirkland Signature Extra Strength Vitamin D3 is an inexpensive way to stay up on your vitamin D intake.
Points to consider
Requires a membership
If you prefer to purchase your vitamin supplements in stores, you may be out of luck. The Kirkland Signature brand is exclusive to Costco, which requires its shoppers to purchase a monthly membership fee. While we did find it available for sale on Amazon, you’ll need the Costco membership for a cheaper price.
Why we chose it
Nature Made is the only other D3 supplement tested by both USP and Labdoor to ensure purity and potency, plus it includes soybean oil to help boost absorption.
Unlike Kirkland Signature, this product is available in most brick-and-mortar stores. You can pick your supplement up membership-free while out running errands. You can find it at grocery stores and pharmacies nationwide including Target, Walgreens, and Safeway.
Points to consider
Nature Made also only contains 1000 IU of vitamin D per pill (half as much as Kirkland Signature). Our experts recommend 2000 IU per day to most of their adult patients. If your doctor agrees, you’ll need to take two pills per day. But the tablets are tiny, and a lower dose does mean you can easily take more or less vitamin D as needed.
Guide to vitamin D
How to make sure you’re getting enough vitamin D
Deficiency is common
An estimated 41% of US adults are vitamin D-deficient, and that has serious long-term effects. “Without vitamin D you won’t absorb calcium in your gut, which leads to an increase in bone loss,” says Dr. Feuerstein. Shuck adds, “Vitamin D also has other key functions in the body, such as helping to maintain normal immune system functioning.”
Get vitamin D in your diet
There are food sources of vitamin D, notes nutritionist Shereen Lehman: “Oily fish like salmon and tuna have some vitamin D, and eggs do as well. Mushrooms like maitake and chanterelle can be a good source, as can portabella mushrooms grown in UV light. Otherwise, look for foods fortified with vitamin D like milk, breakfast cereals, and many brands of nut milk.”
|Swordfish (3 oz)|
|Sockeye salmon (3 oz)|
|Canned tuna fish (3 oz)|
|Orange juice – vitamin D-fortified (1 cup)|
|Milk (1 cup)|
|Egg (1 yolk)|
But can you get enough D just from food sources? That depends on how hungry you are. The National Institutes of Health (NIH) found that even foods rich in vitamin D require multiple servings to meet the recommended 600 IU per day.
Some medical researchers, like Dr. Michael Holick, recommend getting 15 minutes of unprotected sunlight per day — in the middle of the day when the sun is brightest. And Dr. Andrew Weil recommends 10 minutes of sun per day. But the American Academy of Dermatology disagrees, and suggests we use skin protection (clothing and sunscreen with an SPF of 30 or higher) every time we’re out in the sun, to prevent skin cancer. So what’s the right answer? We suggest checking with your doctor to find out what’s right for you.
Vitamin D FAQs
How do I know if I’m low on vitamin D?
Many doctors routinely check vitamin D levels during a patient’s annual physical exam. A simple blood test, called the 25(OH)D, will determine the amount of vitamin D stored in your body from all sources, including sun, diet, and supplements. In fact, the test measures stored vitamin D as far back as 15 days, which makes it the ideal way to get an accurate measurement of your vitamin D level. If your doctor doesn’t already check your vitamin D levels during your annual exam, just ask for the test.
Another option: a home testing kit for under $70 from the Vitamin D Council. You prick your finger and place a drop of blood on blotting paper, and then send it to the lab, which will mail you your results.
If your test determines that you’re deficient in vitamin D, Dr. Feuerstein suggests working with your medical provider to determine the best dosage — and getting tested every six months until you reach your goal. He routinely tests his patients twice a year to determine if their vitamin D level changes from summer to winter.
What does vitamin D do for my health?
Scientists have known for years that vitamin D plays a key role in creating and maintaining healthy bones. But as Dr. Feuerstein explains, we’re learning more every day. “We have vitamin D receptors in nearly all the tissues of the body, and we’re learning about its effect on cancer, heart disease, multiple sclerosis, and in autoimmune disease.”
The Mayo Clinic makes a strong case for the far-reaching benefits of vitamin D with a list of 59 medical conditions that are either improved by vitamin D or affected in ways that warrant further study. This list includes thyroid conditions, fibromyalgia, psoriasis, dental cavities, and even Alzheimer’s disease.
The takeaway? Research suggests there are plenty of good reasons beyond maintaining healthy bones to make a vitamin D supplement part of your daily regimen.
Can you get too much vitamin D?
Yes. The Institute of Medicine (IOM) says the average adult should take no more than 4000 IU of Vitamin D per day. The Recommended Daily Allowance for most adults is 600 IU. But the majority of the supplements we looked at contained between 1000 and 2000. Why so much? Our experts suggested that the RDA — which dropped from 2000 IU all the way down to 600 IU in 2010 — might not be enough to prevent a vitamin D deficiency.
But there’s no hard and fast rule — and much of it depends on environmental factors. An office worker in cloudy Seattle will likely need more vitamin D than a lifeguard in Los Angeles, for example. Before you start taking supplements, talk to your doctor about the right dosage for you.