The supplement industry has grown exponentially in the last decade, evident from the dizzying array of vitamins on store shelves. Pills, powders, capsules, liquid drops, gummies — which is better?
Manufacturers often claim that liquid vitamins are absorbed better than capsules, but there's not enough scientific evidence to support that.
The rate of absorption may matter more than the amount absorbed when it comes to the effectiveness of liquid vitamins versus capsules.
Absorption of Vitamin Supplements
There is a dearth of quality scientific research on how the body absorbs supplemental vitamins in any form, whether powder, capsule or pill. Pre-market testing isn't required by the FDA and, although supplement makers are required to follow good manufacturing practices, there is little regulation beyond that.
Some of the best vitamin brands test their products for quality, efficacy and dissolution times, according to the Dr. Rath Research Institute, but that doesn't provide enough evidence to substantiate claims that one type of supplement is better than another in terms of absorption and bioavailability.
One claim made about liquid vitamins is that they are absorbed more effectively and more quickly into the bloodstream because they are not part of a solid pill or enclosed in a capsule that must dissolve before the nutrients are released. Whether or not this makes them any more effective for nutrient delivery or usability isn't confirmed — and it probably can't be, given the vast array of formulations of vitamin supplements on the market and all the factors that affect nutrient bioavailability.
Liquid Vitamins vs. Capsules
The bioavailability and absorption rate of a nutrient is dependent on many factors, including the other ingredients in the liquid or capsule that may or may not enhance the absorption of the nutrient. For example, according to a review published in Asia Pacific Journal of Tropical Biomedicine in April 2013, extracts of aloe vera can increase the bioavailability of vitamins C and E. Other factors that affect absorption and bioavailability include:
- The form of the vitamin — for example, there are several forms of vitamin C on the market, including ascorbic acid, Ester-C, sodium ascorbate and ascorbyl palmitate, all of which potentially have varying degrees of bioavailability, according to a review published in the journal Advances in Nutrition in November 2013.
- Whether the vitamin is natural or has been made synthetically.
- Fillers or additives in both capsules and pills.
Finally, absorption can't be tested in a vacuum; it has to be tested on humans. And humans are not constant. In the case of B12, for example, a substance secreted by the stomach called intrinsic factor is required for absorption and utilization.
Various health conditions may affect how much intrinsic factor a person's body is able to make, which will determine how much of a B12 supplement an individual can absorb. All of these variables hinder bioavailability research, according to the authors of the Advances in Nutrition review.
As for claims that liquids are absorbed more quickly than capsules or other supplement forms, this is a good marketing technique to make consumers believe that liquid is more effective; but, absorption rate and bioavailability aren't the same concepts.
According to the Dr. Rath Research Institute, fast absorption isn't necessarily better. In fact, for essential nutrients, it may make the supplement less effective. The body can absorb only so much of a nutrient at one time, and any excess is excreted.
Read more: The 14 Best Foods for Your Heart
How Should You Choose?
Rather than worrying about whether a capsule or liquid vitamins will be better absorbed, you should make the decision based on quality, cost and personal preference. Each supplement form has pros and cons. Compared to capsules, liquids may be preferable because:
- They make it easier to modify doses for children or the elderly.
- They may be easier for some people with digestive problems due to gastric surgery.
- They are easier to swallow for people who have trouble taking pills.
The cons of liquids versus capsules include:
- Liquids may be less stable, which will cause more rapid nutrient losses. This is especially true of vitamin C and folic acid, according to ConsumerLab.com.
- They may require refrigeration, which can make them less practical.
- As mentioned, their fast absorption may make them a poor choice for certain nutrients.
As for cost and quality, both liquid and capsule vitamin supplements can be expensive. Often, high-quality vitamins will be more expensive because they contain better ingredients, fewer fillers and may have undergone more rigorous testing. But, this isn't always the case. Sometimes, lower cost supplements can be just as effective — but again, it's hard to assess this.
Before you choose, do your research to check on the reputability of the manufacturer and the best vitamin brands. You can also look for a seal from a third-party testing agency that assures that the product was manufactured properly, that it contains the ingredients appearing on the label, and that it doesn't contain harmful levels of contaminants. Reputable agencies that provide third-party testing and approval seals include:
- U.S. Pharmacopeia
- NSF International
Keep in mind, this doesn't necessarily guarantee the safety or effectiveness of the product.
Do You Need a Supplement?
Whether it's delivered in a dropper or a capsule, absorbed quickly or not at all, the real question is — is it going to do anything for you? For most people, the answer is no, says Larry Appel, M.D., director of the Johns Hopkins Welch Center for Prevention, Epidemiology and Clinical Research. Here are some circumstances that may require a supplement:
- Your doctor recommends it to repair a deficiency or aid a specific condition.
- You have problems absorbing nutrients from food due do a digestive disorder such as celiac or Crohn's disease.
- You have another medical condition that affects absorption of nutrients from food.
- You take a medication, such as proton-pump inhibitors, that inhibits dietary nutrient absorption.
- You eat a restrictive diet that does not include one or more food groups. For example, vegans often benefit from a B12 supplement.
Many people use vitamins as "nutritional insurance," hoping that they will make up for a less-than-healthy diet. But do you know what's better than taking a pill to boost your nutrition? Eating a healthy diet.
Read more: 12 Foods With Surprising Health Benefits
Instead of spending money on supplements you most likely don't need, it's better to invest in your health by buying and eating high-quality foods such as organic fruits and vegetables, grass-fed, hormone-free, organic eggs, meat and dairy, and fresh seafood. Then, take any money that's leftover and invest in a gym membership if you don't already have one. The combination of a healthy diet and exercise is more likely to improve your health than a drop or pill.
- NIH: "Dietary Supplements: What You Need to Know"
- Dr. Rath Research Institute: "Nutritional Supplements - Which Form Is Better?"
- Asia Pacific Journal of Tropical Biomedicine: "Bioavailability Enhancers of Herbal Origin: An Overview"
- Advances in Nutrition: "Recent Developments in Multivitamin/Mineral Research"
- Wellness Center for Research & Education: "Toxins in Supplements"
- Colorado State University: "Intrinsic Factor"
- Johns Hopkins Medicine: "Is There Really Any Benefit to Multivitamins?"
- Gluten Intolerance Group: "Nutrient Deficiencies"
- Harvard Health Publishing: "Are Your Medications Causing Nutrient Deficiency?"
- NIH: "Vitamin B12"