Question: Is it better to get vitamins from foods or supplements, and are natural vitamins better than synthetic vitamins?
Answer: It is generally best to get your vitamins (as well as minerals) naturally from foods or, in the case of vitamin D, controlled sun exposure. For example, recent research on the mineral calcium suggests that it is safest to get your calcium from foods that are naturally rich in calcium than from supplements. Older women who get high amounts of calcium from supplements seem to have a higher risk of kidney stones, strokes, and even a greater risk of dying over periods of time. A small increased risk of death has also been seen in studies of people taking supplements containing vitamin A and beta-carotene compared to those who did not.
Exceptions to the "foods are better" rule are two B vitamins. Ten to thirty percent of older people don't properly digest and absorb natural vitamin B-12 from foods, so it is recommended to get B-12 from a supplement if you are over age 50. Folic acid (vitamin B-9) from supplements and fortified foods is absorbed twice as well as from regular food. Consequently, pregnant woman are advised to get folic acid from a supplement (or fortified food) as well as regular foods. Also keep in mind that if you get your iron from plant foods, it is absorbed only half as well as iron from meat -- although eating your spinach (or iron supplement) with a source of vitamin C will boost the absorption of its iron.
Using supplements made from whole foods won't necessarily give you more vitamins (in fact, they typically contain more modest amounts of vitamins than other dietary supplements), but you will get other plant compounds which could be of potential benefit (as well as some grams of fiber if you are consuming, for example, spoonfuls of a whole food powder as opposed to a pill). Paying a premium price for this, however, may not be worthwhile and ConsumerLab.com has found lead contamination in some whole food and "greens" products.
Regarding natural vs. synthetic forms of vitamins in dietary supplements, sometimes natural is better, sometimes synthetic is better, and sometimes it doesn't matter. Keep in mind that all can help prevent or treat deficiencies and other conditions, and nearly all are known to be harmful at too high a dose.
Natural may be better in the case of vitamin E. At low doses, either natural (d-alpha-tocopherol) or synthetic (dl-alpha-tocopherol) can be fine, although you need more IUs of synthetic (1.6 IU) to get the same amount of active vitamin E as from 1 IU of natural vitamin E. There is also a greater risk of bleeding problems with synthetic vitamin E at high doses, so that the upper limit for vitamin E for adults is 1,100 IU of synthetic vitamin E, but 1,500 IU of natural vitamin E. Naturally, vitamin E also contains other tocopherols and tocotrienols, which may have benefit. However, ConsumerLab.com tests show that not all "natural" vitamin E products contain these additional natural compounds.
Natural may also be better with vitamin K. A form of vitamin K-2, known as MK-7, naturally derived from fermented soy beans and used in supplements is better at raising vitamin K levels than supplements with synthetic K-1 or synthetic K-2, known as MK-4.
Natural or synthetic sources are both fine for getting vitamin C. Rose hips or acerola or synthetically produced vitamin C all provide the same compound -- ascorbic acid. The inclusion of citrus bioflavonoids (naturally present or added) may improve absorption.
Sometimes synthetic forms of vitamins offer advantages over natural forms. A synthetic form of niacin (vitamin B-3) called inositol hexanicotinate, for example, causes less flushing of the skin than niacin.
Use the links above to get more information about each vitamin or mineral, including ConsumerLab.com's tests and reviews of supplements containing those nutrients. For recommended daily intakes of these and other vitamins and minerals also see the Recommended Daily Intake tables, which includes upper intake limits.
Question: I've been buying nutritional supplements in powder form, as I find them cheaper than tablets and capsules. I am concerned about the effect of air when I open the bottles daily because sometimes my powdered supplements get clumpy. Should I be concerned?
Question: After several weeks of taking a vitamin C supplement, my wife noticed blood in her urine along with difficult and painful urination. This stopped a week after discontinuing the supplement, but started again when she resumed taking the vitamin C. Could there be glass in the supplement?
Answer: The pain and blood in her urine could have been caused by vitamin C itself rather than by a contaminant. See the Concerns and Cautions section of the Vitamin C Supplements Review for a full explanation >>.
Question: What is Lipo-flavonoid and does it work for tinnitus or other ear problems?
The product is actually a formula consisting of several ingredients. The main ingredient is a lemon flavonoid extract containing eriodictyol glycoside and other flavonoids. The product also contains several B vitamins, vitamin C, choline, and inositol.
In the 1960s, a paper was published describing 122 cases of Meniere's disease that were treated with a lemon flavonoid complex containing eriodictyol glycoside. Many people reported reduced vertigo and improved hearing (Williams, Ann Otol Rhinol Laryngol 1963). A paper published in 1947 described 87 cases of vertigo, often as a result of Meniere's disease, treated with pyridoxine (B6), usually 100 mg daily. Many people reported improvement (Lewy, Arch Otolaryngol 1947).
Based on these reports, some have assumed that these ingredients would be beneficial for a variety of ear disorders including tinnitus and others. However, these reports are very preliminary. Neither Lipo-flavonoid Plus, nor its main ingredient, have been evaluated in reliable clinical studies for tinnitus or other ear-related conditions.
Question: Which supplements have been shown to be helpful for autism?
Multivitamins and minerals -- These are one of the most widely recommended supplements by physicians for children with autism. One randomized, double-blind, placebo-controlled study involving 141 children and adults with autism found supplementation with a specially formulated liquid multivitamin/mineral (see ingredients and amounts here) which also contained CoQ10, MSM and N-acetylcysteine (NAC), improved the nutritional and metabolic status of children with autism, and significantly reduced symptoms such as hyperactivity and tantrums (Adams, BMC Pediatrics 2011). The supplement was given in three equal doses at breakfast, lunch and dinner. For more about multivitamins, including our most recent product tests and reviews, see the Multivitamin Supplements Review >>
Melatonin -- Many children with autism have difficulty falling asleep or staying asleep. In fact, an estimated 50% to 80% of children with autism spectrum disorders may suffer from sleep difficulties or insomnia (Malow, J Autism Dev Disord 2013). Several studies have found individuals with autism to have lower levels of melatonin or melatonin metabolites than those without autism (Rossignol, Dev Med Child Neurol 2011). An analysis of 18 studies of people with autism (mostly children between the ages of 2- 18, although two studies included individuals over the age of 18) found that melatonin supplementation (in doses ranging from 0.75 mg to 25 mg daily) significantly improved the time it took to fall asleep and sleep duration, and, in some individuals, also improved daytime behavior (Rossignol, Dev Med Child Neurol 2011). Another study also found that a daily dose of 1 mg or 3 mg of melatonin improved sleep latency in children with autism spectrum disorder (Malow, J Autism Dev Disord 2013). For more about melatonin, including our most recent product tests and reviews, see the Melatonin Supplements Review >>
Probiotics -- Children with autism can experience significantly more gastrointestinal symptoms, including diarrhea, constipation and abdominal pain, than others (McElhanon, Pediatrics 2014), and probiotics may be helpful for some of these symptoms.
Because abnormal gut microbiota and gastrointestinal dysfunction in children with autism has also been associated with increased irritability, tantrums, aggressive behavior and sleep disturbances, researchers have proposed further study of the use of probiotics (Critchfield, Gastroenterol Res Pract 2011). One interesting, preliminary animal study found a specific bacterial strain, Bacteroides fragilis, improved gut permeability and autism-like behaviors in mice (Hsiao, Cell 2013). For more information about specific strains used to reduce abdominal pain, and our most recent product tests and reviews, see the Probiotic Supplements Review>>
N-acetylcysteine (NAC) -- This amino acid has been found to reduce irritability, but not other symptoms, in children with autism (Hardan, Biol Psychiatry 2012) and in children taking risperidone (an atypical antipsychotic drug sometimes prescribed for people with autism) (Ghanizadeh, BMC Psychiatry 2013). The dose in these studies ranged from 900 mg to 2,700 mg daily, which was generally well tolerated. (ConsumerLab.com will be testing NAC supplements later in 2014).
L-carnosine -- An 800 mg daily dose of L-carnosine for 8 weeks in children with autism was found to significantly improve scores on the Gilliam Autism Rating Scale in a small clinical study (Chez, J Child Neurol 2002).
L-carnitine -- One preliminary clinical trial found that L-carnitine, taken daily (50 mg per kg bodyweight) as a liquid supplement, significantly improved clinical measures of autism spectrum disorder in children (Geier, Med Sci Monit 2011).
Ubiquinol -- Some research on autism has proposed oxidative stress as a potential cause of neuronal dysfunction and clinical symptoms in autism (Gvozdjakova, Oxid Med Cell Longev 2014). Ubiquinol, which is the active form of CoQ10, taken at 50 mg twice per day, at morning and lunchtime, for three months, was found to improve communication, sleep, and decrease food rejection in a small study of children with autism, based on parental reports (Gvozdjakova, Oxid Med Cell Longev 2014). The authors noted that in the first days of supplementation, a small subset of children had increased anger, hyperactivity or sleep disturbance, which was managed by modifying the timing of the doses to morning and evening. For more about ubiquinol, including our most recent product tests and reviews, see the CoQ10 & Ubiquinol Supplements Review>>
Vitamin C -- One small study found significant improvements in behavior in autistic children who received a high dose of vitamin C (8,000 mg per 70 kg of body weight) daily when compared to placebo. (Dolske, Prog Neuropsychopharmacol Biol Psychiatry 1993). It is important to note, however, that taking such a large dose of vitamin C may cause diarrhea in some people. For more about Vitamin C, including our most recent product tests and reviews, see the Vitamin C Supplements Review >>
See ConsumerLab.com’s Encyclopedia article on Autism for more information about supplements that may or may not be helpful.
Question: Do any supplements help prevent sunburn or skin damage from sun exposure?
Answer: Supplements containing beta-carotene, cocoa, vitamin C, and/or vitamin E may provide modest protection from sun damage to the skin, according to small studies. Certain herbal supplements, however, may actually increase photosensitivity. Get the Full Answer >>
Question: Some websites claim that synthetic vitamin C in supplements may be a combination the active "L" form and the inactive "D" form of ascorbic acid. Is that true? Should I be concerned?
Answer: While it is true that only L-ascorbic acid (or L-ascorbate) is active, modern processes for manufacturing vitamin C for supplements produces only this form. So you would not get the "D" form from a supplement. For more information about vitamin C, including our tests and comparisons of supplements, see the Vitamin C Supplements Review >>
Question: Is liposomal vitamin C (sold as Lypo-Spheric) better than other forms of vitamin C?
Answer: A liposomal formulation of vitamin C appears to have been developed to boost the absorption of vitamin C beyond levels normally attained with other formulations. However, whether or not it achieves this, and whether this is even a desirable effect, is debatable, based on the current evidence. For details about this and other forms and formulations of vitamin C, see the Vitamin C Supplements Review >>
Question: Is there cause for concern with "gummy vitamins?" There are many different gummies out there. Are some better than others?
Answer: When gummies first became popular, ConsumerLab.com found that some did not contain their listed amounts of vitamins or minerals, or contained impurities. We have seen improvements in quality over time, but continue to find more problems with candy-like vitamins than with traditional forms, such as tablets and caplets. Manufacturing challenges associated with candy-like products likely explain the higher incidence of problems.
A benefit of gummies is that they may be more palatable than a pill. Also, being chewable, there is not the risk that the product won’t properly break apart, as there is with a tablet.
A risk with any candy-like supplement, particularly with children, is that too many will be consumed, potentially resulting in toxicity. It’s therefore best to give young children vitamins as needed and not leave them out. Also, keep in mind that not all vitamins and other ingredients are easily incorporated into gummies, so, if you are interested in a gummy supplement, check that it lists the ingredients you want.
Question: Is it possible to take too much vitamin C?
Answer: Yes, it's possible to take too much vitamin C. Since vitamin C is water-soluble (excess amounts are excreted and do not accumulate in the body), people sometimes assume there is no harm in taking large doses. However, there are potential short-term and long-term problems with taking high doses (500 to 1,000 mg per day) or very high doses (more than 2,000 mg per day) of vitamin C.
Very high doses of vitamin C are known to cause gastric discomfort and diarrhea, and this is the basis for the current upper tolerable daily intake limit of 2,000 mg for adults.
More limited, but concerning, evidence suggests problems with daily doses of just 500 to 1,000 mg of vitamin C. (Keep in mind that the recommended daily intake of vitamin C for adults is only 75 mg to 120 mg, with an additional 35 mg for smokers -- see the RDAs for details).
For example, while long-term, low-dose supplementation with vitamin C may help to prevent cataracts, high doses may actually increase the risk. Taking a several hundred milligrams of vitamin C daily may also hamper some of the benefits of endurance exercise, as has been found with high doses of other antioxidant vitamins and supplements.
High doses of vitamin C may also reduce the effectiveness of certain medications, and increase the risk of liver damage when taking high doses of Tylenol. They may also interfere with tests for cholesterol and blood sugar, and for blood in the stool.
Individuals prone to developing kidney stones or with defects in metabolizing vitamin C or oxalate should also limit vitamin C from supplements.
Question: Do any supplements help with gum disease or periodontitis?
Answer: Several different types of supplements may be helpful in improving gum disease and/or periodontitis -- the inflammation around the teeth causing pocketing -- such as DHA from algal oil, gamma-linolenic acid (GLA), lycopene, green tea, cranberry extract, and a certain type of probiotic. For details, including dosage, see the full answer >>
Question: I thought the B vitamins were all water soluble and did not build up in the body, so you would not build up toxic levels. Am I wrong?
Answer: Although B vitamins are water soluble and don't stay long in your body, large doses of certain B vitamins can cause serious toxicity, as summarized below. The same is true of vitamin C -- the other water soluble vitamin.
Unfortunately, there is no requirement for supplement labels to warn of these toxicities. As we have shown in our B Vitamin Supplements Review, many vitamins and energy drinks exceed the established Upper Tolerable Intake Levels (which vary by age) for B vitamins. If you have an established deficiency, high doses may be necessary; otherwise, remember that "more" does not necessarily mean "better."
Question: Do any supplements help prevent or improve cataracts?
Answer: A number of supplements have been promoted to preventing or improving cataracts. These include multivitamins, vitamin A, C, and E: the B vitamins niacin, thiamin, and riboflavin; lutein, zeaxanthin, astaxanthin, carnosine, NACA, and St. John's wort. The evidence, however, is better for some than for others. Get the details in the full answer >>
See the Encyclopedia article on Cataracts for more information.
Question: I take estrogen replacement (Vagifem), to help relieve the symptoms of menopause. Are there supplements I should avoid, or be taking, due to this drug?
Answer: Oral estrogen replacements, as well as estrogen creams and tablets (Vagifem, Estrace) can be affected by certain supplements and foods. See the full answer >>
Question: Which supplements can help to lower blood pressure?
Answer: There are many supplements, including CoQ10, fish oil, curcumin, certain probiotics, cinnamon and others, which may lower blood pressure. However, if you already take medication to lower blood pressure, always consult your physician before using these supplements, as they may lower your blood pressure too much, or interfere in some other way with your current medication. Be aware that a number of supplements can increase blood pressure. Sign in to see the full answer >>
See the Encyclopedia article about Hypertension for more information.
Question: Which supplements are helpful for age-related macular degeneration (AMD)?
Answer: As discussed in the Vision Supplements Review, lutein, zeaxanthin and zinc supplements may help to slow the progression of age-related macular degeneration, but won't improve the condition. People with age-related macular degeneration who have low blood levels of lutein may be more likely to benefit from lutein supplements. There is also evidence that lutein and zeaxanthin may only help in people with low macular pigment density.
Two of the largest studies on supplements for eye health, known as the Age-Related Eye Disease Study (AREDS and AREDS 2), have helped narrow in on the best combination of ingredients for AMD. ConsumerLab.com has found that many supplements promoted as "vision formulas" do not necessarily contain the right formula. However, we've identified one product that most closely resembles this formula, as well as several others which may be helpful.
Interestingly, while it has been shown that people with higher intakes of the omega-3 fatty acids EPA and DHA from their diet (i.e. from one or more servings of fish per week) are 42% less likely to develop age-related macular degeneration compared to those who eat less than one serving of fish per month, adding EPA and DHA from fish oil to the AREDS formulation did not provide additional benefit.
For more information about the evidence, dosage, tips for choosing and using supplements for age-related macular degeneration — as well as our tests and reviews of popular products, see the Vision Supplements Review >>
Question: Do any supplements help for irritable bowel syndrome (IBS)?
Answer: Several different types of probiotics have been found to reduce symptoms of IBS, but the appropriate probiotic may depend on whether the IBS is causing predominantly diarrhea or constipation. (See the "What It Does" section of the Probiotic Supplements Review for details.)
Prebiotics have also been promoted for IBS, although the evidence is mixed.
Interestingly, several small studies suggest melatonin may improve symptoms of IBS, possibly by affecting the nervous system in the digestive track. (See the "What It Does" section of the Melatonin Review for details).
Preliminary evidence suggests psyllium, a type of fiber, may be helpful for people with IBS with constipation.
Information about other potentially helpful supplements, including peppermint oil and flaxseed, is found in the Encyclopedia article about IBS.
Be aware that a number of supplements, including fish oil, magnesium, high doses of vitamin C, berberine and turmeric/curcumin can cause diarrhea, so you may want to avoid these or reduce your dosage if you find they are exacerbating IBS symptoms. See the "Concerns and Cautions" section in each review for details.
Question: Are there negative interactions between the following supplements I take twice each day, as well as 60 mg of beta-sitosterol with dinner: Vitamin C (500 mg), CoQ10 (100 mg), grape seed extract (100 mg), fish oil (500 mg), vitamin D3/calcium/magnesium/zinc (200 IU/333 mg/113 mg/5mg)?
Answer: You may want to cut back on the vitamin C. The required daily intake is not even 100 mg and if you already get that, taking another 500 mg or 1,000 mg may actually reverse vitamin C's ability to reduce the risk of cataracts, as noted in the Vitamin C Supplements Review.
The amounts of the other supplements you take are generally safe and are at doses which may be helpful -- depending on your health conditions. It is also good that you have broken up your intake of calcium over the day, since you can't absorb more than 500 mg at a time, as discussed in the Calcium Supplement Review.
If you have high blood pressure, be aware that one study found the combination of vitamin C and OPCs (the active component of grape seed extract) to increase blood pressure (as noted in the Safety Issues section of the article on OPCs).
The beta-sitosterol which you take is at a dose which may help with symptoms of an enlarged prostate. Be aware that beta-sitosterol is also used at a much higher dose for lowering cholesterol (by competing with cholesterol for absorption in the gut) and, at this higher dose, you would not want to take it at the same time you take the fat-soluble supplements -- vitamin D and CoQ10, both of which are best taken with a meal containing some fat.
If you take also take prescription medications, be sure to look up the supplements with which they may interact using our Drug Interactions information.
Note: ConsumerLab.com staff is not able to regularly respond to requests from members to evaluate their supplement regimens. However, it tries to do so from time-to-time and often responds to questions of more general interest, such as those below.
Question: After developing kidney stones, I was told to avoid tea -- but recently I've heard that green tea might actually be helpful for kidney stones. Is that true?
Answer: As discussed in the Green Tea Review, both black and green tea contain oxalate, high levels of which can contribute to the development of kidney stones in some people. However, for a number of reasons, this is not much of a concern with green tea (which may even help), and there are even ways to minimize the kidney-stone risk when drinking black tea. Get the details in the "Concerns and Cautions" section of the Green Tea Review >>
Be aware that too much calcium or vitamin C from supplements may increase the risk of kidney stones.
For information about other supplements that may be helpful or harmful regarding kidney stones, see the Encyclopedia article about Kidney Stones.
Question: Which supplements can help lower or control my blood sugar?
Answer: Many different supplements may help lower or control blood sugar in people with prediabetes or type 2 diabetes who experience hyperglycemia (when blood glucose rises higher than normal). These supplements are discussed below. More details about each, including dosage, drug interactions, potential side effects, and ConsumerLab.com's reviews of products on the market, can be found by clicking on the links.
Due to the seriousness of hyperglycemia, it is important to consult with your physician regarding use of these supplements.
Cinnamon supplements may modestly improve blood sugar in people with type 2 diabetes whose blood sugar is not well controlled with medication. In addition, one small study found that a branded cinnamon extract reduced fasting blood sugar by an average of about 10 mg/dL in prediabetic men and women with metabolic syndrome. Keep in mind, however, that only certain varieties of cinnamon have been shown to have this effect, and long-term safety studies have not been conducted.
Curcumin (from turmeric) may improve blood sugar levels, according to preliminary studies, and one study found curcumin to dramatically lower the chances of prediabetes in middle-aged, slightly overweight men and women with somewhat higher than normal blood sugar levels.
Alpha lipoic acid may improve insulin sensitivity and blood sugar control in people with type 2 diabetes, although it may only slightly reduce levels of glycosylated hemoglobin (HbA1c).
Chromium picolinate may help some people with type 2 diabetes decrease fasting blood glucose levels as well as levels of insulin and glycosylated hemoglobin (HbA1c). However, be aware that high doses may worsen insulin sensitivity in healthy people who are not obese or diabetic.
Having adequate blood levels of vitamin D may reduce the risk of insulin resistance in people who are obese. There is some evidence that a certain blood level of vitamin D is needed for normal glucose metabolism in women who are overweight and obese (but not diabetic), but it is not clear whether any further benefit is gained with higher blood levels.
In healthy people, consuming a moderate amount of olive oil with a meal has been shown to reduce increases in blood sugar after the meal compared to the same meal consumed with corn oil. In people with type 1 or type 2 diabetes, olive oil may improve glucose metabolism.
Increasing dietary fiber, especially insoluble fiber from cereal and grains, is associated with a reduced risk of diabetes and has been shown to reduce fasting blood glucose and modestly lower HbA1c in people with type 2 diabetes (Martin, J Nutr 2008; Post,J Am Board Fam Med 2012). In people with type 1 diabetes, 50 grams of dietary fiber per day has been shown to significantly improve blood sugar control and reduce hypoglycemic events (Giacco, Diabetes Care 2000). The American Dietetic Association states that "diets providing 30 to 50 g fiber per day from whole food sources consistently produce lower serum glucose levels compared to a low-fiber diet. Fiber supplements providing doses of 10 to 29 g/day may have some benefit in terms of glycemic control." (Slavin, J Am Diet Assoc 2008). Although ConsumerLab.com has not tested fiber products, we have produced a webinar about that provides more information.
Ginseng, both American and Korean Red ginseng (from Panax ginseng), may reduce blood sugar levels in people with diabetes, according to preliminary research.
Drinking whey protein before a high glycemic meal may help to lessen increases in blood sugar after the meal in people with well-controlled type 2 diabetes.
Silymarin, a component of milk thistle, may decrease blood sugar and hemoglobin A1c in people with type 2 diabetes, and reduce insulin resistance in people with coexisting diabetes and alcoholic cirrhosis.
Inulin, a type of prebiotic, may improve measures of blood sugar control in women with type 2 diabetes, although it did not improve blood sugar levels or insulin resistance in a study of prediabetic men and women.
Berberine (a compound found in plants such as barberry, Oregon grape and goldenseal) may reduce blood sugar levels in people with metabolic syndrome or type 2 diabetes, according to a few small studies.
Fenugreek may help to lower blood sugar, according to preliminary studies, and one study found fenugreek extract to significantly improve some measures of blood sugar control and insulin response in people with type 2 diabetes.
White mulberry (Moruns alba or Morus indica) has been traditionally used in Asia to help treat type 2 diabetes, and there is some preliminary evidence to support this use. Mulberry leaf extract (species not given) may lessen increases in blood sugar after ingestion of table sugar in healthy people and people with type 2 diabetes (Mudra, Diabetes Care 2007). Among people with type 2 diabetes, taking 1 gram of powdered white mulberry leaf three times daily (after breakfast, lunch and dinner) for four weeks was found to lower fasting blood sugar by 27%, while taking 5 mg of the anti-diabetes drug glibenclamide lowered fasting blood sugar by only 8% (Andallu, Clin Chim Acta 2001).
There is mixed evidence as to whether CoQ10 may lower blood sugar. To be safe, people with diabetes or who take medication to lower blood sugar should consult a physician before using.
There are a few supplements which may worsen blood sugar control or insulin sensitivity in certain people: excessive amounts of niacin may elevate blood sugar levels, and prescription digestive enzymesmay cause an increase or decrease in blood sugar levels in people with exocrine pancreatic insufficiency. CLA (conjugated linoleic acid), a popular supplement for slimming, may worsen blood sugar control in diabetics and in obese people without diabetes.
Although fish oil does not appear to adversely affect blood sugar levels in people with diabetes, one study reported that a large daily dose of krill oil (providing a modest amount of EPA and DHA) reduced insulin sensitivity in overweight, middle-aged men by about 27% -- which could potentially increase the risk of diabetes.
Also note that high doses of vitamin C may increase blood sugar or interfere with certain blood sugar tests.
Question: I've been taking a Daily Advantage multi but am now concerned by the very high % DV for vitamin C (833% DV), niacin (325% DV), and B vitamins (over 1,000% DV for several). The company tells me this formula is based on clinical experience and the scientific literature. What do you think?
Answer: Unless you are deficient in each of these vitamins you don't need to take such high doses of each. Some may being doing more harm than good. It's good that you are now studying the ingredients listed on the label. You may still benefit from a multivitamin, but one which is likely to fill your nutritional gaps without exceeding upper tolerable intake levels.
The following resources on ConsumerLab.com can help you:
Question: Are the "% DV" numbers on vitamin supplement labels really based on what I need?
Answer: Unfortunately, the % DV (percent of Daily Value) numbers are not nearly as useful as they could be. One reason is that they are woefully out of date. The DVs are based on calculations done in 1968 (with some additions in 1989) and do not reflect the latest intake recommendations from the Institute of Medicine which show that some DVs are too high and others are too low. In addition, the DVs do not distinguish nutritional needs by age and gender since the DVs are intended to cover healthy adults and children over 4 years of age (except pregnant and lactating women), while the needs of people vary significantly within this expansive group — even between men and women of the same age.
In some situations, the DVs actually exceed the upper tolerable intake levels for adults and/or children. In these cases, when you get 100% or more of the DV from a supplement, you are actually putting yourself at risk of toxicity.
In other situations, 100% of the DV or more is simply much higher than the current recommendations. What appears be 100% of the DV could actually be as much as 1,000% of what you need.
For several popular vitamins and minerals, if you get 100% of the DV, you are actually getting much less than the current recommendations.
The DVs do not include the special needs of women or are pregnant or lactating, whose needs are often much greater than 100% of the DV.
The nutrients for which the DVs can be particularly misleading are vitamin A, vitamin B12, vitamin C, vitamin D, vitamin K, biotin, calcium, chromium, copper, folate, iron, iodine, magnesium, molybdenum, niacin, pantothenic acid, potassium, and zinc.
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Product Review:Vitamin C Supplements
Initial Posting: 1/24/14 Last Update: 8/3/16
Vitamin C Not Accurately Listed on 27% of Supplements
Find Out Now If Yours Passed!
Vitamin C supplements compared in this review
Gary Null's Suprema C Strawberry
Rainbow Light Gummy Vitamin C Slices
Bronson Laboratories Vitamin C Crystals
GNC Vitamin C 1000
Rexall Vitamin C
ChildLife Liquid Vitamin C
Halls Defense Vitamin C Strawberry
Solgar Ester-C Plus
CVS Pharmacy C
Kirkland Signature (Costco) Vitamin C
Spring Valley C
Douglas Laboratories Ester C Plus
Life Extension Vitamin C with Dihydroquercetin
Trader Joe's Chewable Oranges & C
Dynamic Health Laboratories Liquid Vitamin C 1,000 mg
Nature Made VitaMelts Vitamin C
TwinLab C-1000 Caps
Nature's Plus Animal Parade Vitamin C
Vitacost Vitamin C
NutriGold Vitamin C Gold
Vitafusion Power C
Finest Nutrition (Walgreen) C Vitamin
Nutrilite Vitamin C Plus
Vitamin World C-1000 mg
Garden of Life RAW Vitamin Code Raw Vitamin C
Puritan's Pride C-1000 mg
Make sure the vitamin C supplement you take passed our quality review and is right for you!
Isn't your health worth it?
Should you be taking a vitamin C supplement? Which are the best vitamin C supplements in terms of quality and value?
Vitamin C is an antioxidant critical for maintaining healthy connective tissue. Research shows that getting too little can be a problem, but so can getting too much. Unfortunately, our tests of vitamin C supplements found that more than 25% of the products selected for review didn't contain the amounts of vitamin C listed on their labels. Two high-dose products contained about 40% more vitamin C than listed -- which could cause side-effects for some people -- and one had 15% less than listed.
We also found that a common dose of vitamin C from a high-quality supplement can cost as little as 1 cent, or you can spend over a dollar.
In this comprehensive report about vitamin C supplements, you'll get test results and quality ratings for 28 vitamin C products (including 17 that passed our voluntary Quality Certification Program) and information about one other vitamin C supplement similar to one that passed testing. You'll learn:
Which vitamin C supplements passed testing, and which failed
Which high-quality vitamin C supplements are also lowestcost
What vitamin C can and cannot do for your health
The potential advantages of forms of vitamin C, such as Ester-C, sodium ascorbate, and slow-release vitamin C
The value of additional ingredients, such as bioflavonoids (e.g., quercetin, dihydroquercetin, rutin, and hesperidin), often found in vitamin C supplements
The vitamin C dosage to help prevent or treat conditions such as colds, gout, and vitamin C deficiency
The potential side-effects of vitamin C and other concerns, including the potential for kidney stones and interactions with drugs and diagnostic tests
Question: Is it better to get vitamins from foods or supplements, and are natural vitamins better than synthetic vitamins? Get the answer >>
Question: I've been buying nutritional supplements in powder form, as I find them cheaper than tablets and capsules. I am concerned about the effect of air when I open the bottles daily because sometimes my powdered supplements get clumpy. Should I be concerned? Get the answer >>
Question: After several weeks of taking a vitamin C supplement, my wife noticed blood in her urine along with difficult and painful urination. This stopped a week after discontinuing the supplement, but started again when she resumed taking the vitamin C. Could there be glass in the supplement? Get the answer >>
Question: What is Lipo-flavonoid and does it work for tinnitus or other ear problems? Get the answer >>
Question: Which supplements have been shown to be helpful for autism? Get the answer >>
Question: Do any supplements help prevent sunburn or skin damage from sun exposure? Get the answer >>
Question: Some websites claim that synthetic vitamin C in supplements may be a combination the active "L" form and the inactive "D" form of ascorbic acid. Is that true? Should I be concerned? Get the answer >>
Question: Is liposomal vitamin C (sold as Lypo-Spheric) better than other forms of vitamin C? Get the answer >>
Question: Is there cause for concern with "gummy vitamins?" There are many different gummies out there. Are some better than others? Get the answer >>
Question: Which supplements are helpful for age-related macular degeneration (AMD)? Get the answer >>
Question: Do any supplements help for irritable bowel syndrome (IBS)? Get the answer >>
Question: Are there negative interactions between the following supplements I take twice each day, as well as 60 mg of beta-sitosterol with dinner: Vitamin C (500 mg), CoQ10 (100 mg), grape seed extract (100 mg), fish oil (500 mg), vitamin D3/calcium/magnesium/zinc (200 IU/333 mg/113 mg/5mg)? Get the answer >>
Question: After developing kidney stones, I was told to avoid tea -- but recently I've heard that green tea might actually be helpful for kidney stones. Is that true? Get the answer >>
Question: Which supplements can help lower or control my blood sugar? Get the answer >>
Question: I've been taking a Daily Advantage multi but am now concerned by the very high % DV for vitamin C (833% DV), niacin (325% DV), and B vitamins (over 1,000% DV for several). The company tells me this formula is based on clinical experience and the scientific literature. What do you think? Get the answer >>
Question: Are the "% DV" numbers on vitamin supplement labels really based on what I need? Get the answer >>