Navigating the Supplement Aisle: Understanding the Pros and Cons of Five Popular Dietary Supplements

The Five Most Popular Dietary Supplements

In my post, Navigating the Supplement Maze: Unveiling the Truth and Myth - The Truth About Supplements, I addressed some common misconceptions about dietary supplements.

Today, I address five of the more popular selling supplements. This is based on what I hear and sales numbers. Though what makes the top five varies each year, I chose them mainly because I am often asked about them.

It is important to note that while people ask about these and the sales numbers suggest these are the top-selling supplements, whether people take them consistently is a different story Many tell me they have supplements in their home but don’t consistently take them.

Vitamin D

Role of Vitamin D: it is essential for bone health by helping us absorb calcium, helps nerves do their job (send messages), muscle movement, and helps with a high-functioning immune system.

Proven Benefits of Supplements: vitamin D is limited in food sources, and most of us get it from UV light on our skin (with additional steps to make it active vitamin D); most often, vitamin D is recommended to correct a deficiency. Vitamin D status is measured via a blood test.

Potential Risks: because vitamin D is classified as a fat-soluble vitamin, it can build up to toxic levels. While some supplemental versions (usually prescribed) have high amounts, such as 10,000 I.U. and even 50,000 I.U., these are meant to be a weekly or monthly dose, not daily. Only take this amount with a specific recommendation and prescription.

Does it work? Yes, for correcting a deficiency, but don’t expect that this is the supplement to take when you want to fight a cold or other virus or that it will heal a broken bone or reverse osteoporosis.

Key Message: It's essential to strike a balance and get vitamin D from sunlight exposure and dietary sources like fatty fish and fortified foods. When you get a blood test, your healthcare provider should give you feedback and recommendations for potential supplemental vitamin D.

Learn more: Vitamin D Fact Sheet for Consumers

Fish Oil & Omega-3 Fatty Acids

Fish oil supplements contain omega-3 fatty acids, an essential fat, meaning we must consume them since our bodies cannot make them. All fish oil supplements will be omega-3 supplements, but not all omega-3 supplements are fish oil. There are some other sources of omega-3, such as flaxseeds/oil.

Role of Omega-3 Fatty Acids: it is essential for cellular health and is commonly associated with heart health and brain function. It also helps with the immune and endocrine systems (the system that makes and regulates hormones).

Regarding omega-3s in cardiovascular disease, a systematic review shows less benefit of supplemental omega-3s than eating fish rich in omega-3s. Research continues.

And, the use of omega-3 supplements for brain injury does not show any proven benefit, though it is crucial for brain health, food sources of best. Operation Supplement Safety: Omega-3s and Brain Injury

Proven Benefits of Supplements: Much research shows the benefits of eating omega-3s from food, such as fatty fish, and certain plant foods, such as walnuts, flax seeds, and canola oil. The research shows minimal benefits of supplements. Unless people actively avoid those foods, such as a fish or nut allergy, we see little benefit from the supplements. I used to recommend fish oil supplements to many people. Not as much anymore.

Potential Risks: not much other than a waste of money. It is suggested that high amounts can thin the blood, which is not good if someone also takes an anticoagulant (blood thinner).

Does it work? Only if someone isn’t getting enough omega-3 in their diet. But the supplements won’t keep away heart disease or reduce the chance of dementia. It just isn’t panning out like we once thought.

Key Message: You must eat fish or other sources of omega-3 to ensure this is helpful. Sorry. As I said, I used to recommend this one, but I can't suggest it is helpful when the research doesn’t support its use.

Learn more: Omega-3 Fatty Acids Fact Sheet for Consumers

Multivitamins

Role of Multivitamins: Generally, multivitamins help cover nutrient gaps in various population groups. However, there are many varieties of these supplements (based on age, sex, and other factors) – and with multivitamins, there is no “standard” for what is in them.

People often give multivitamins much more credit for the purported benefits than they have. This isn’t a magic pill to cover everything. And it isn’t the “insurance” people think it is. The amounts of various vitamins and minerals in the multivitamins tend to have plenty of the nutrients people get plenty of – and not as much as the ones people are likely to need.

Proven Benefits of Supplements: As much as people may believe that multivitamins have proven benefits, it is not usually accurate. It is unclear if they affect cancer risk; it is difficult to determine if they affect our chronic disease risk or overall health. Most studies show that multivitamins have little to no effect on overall health outcomes. Benefits are usually in populations that have poor nutrition status to start.

Potential Risks: You can get too many nutrients (again, depending on which multivitamin you choose), such as iron, vitamin A, zinc, and some B vitamins, such as niacin and folic acid.

Does it work? That depends on your definition of “work.” They do provide multiple vitamins and minerals in a single pill. But it won’t prevent or cure any chronic health issue (other than a nutrient deficiency). And, if someone has a specific nutrient deficiency, I recommend correcting that specific nutrient with the food and appropriate supplement rather than a whole slew of other things.

Key Message: Most healthy adults who eat various foods from all the food groups should be okay without a multivitamin in their routine.

There are some exceptions:

pregnancy has some increased nutrient needs, including folic acid;
breastfed babies may need vitamin D supplements (check with the pediatrician);
individuals who follow a vegan diet and don’t eat fortified foods may need B12;
breastfed babies whose parent follows a vegan diet may also need B12;
those over the age of 50 may also need B12

Learn more: Multivitamin/mineral Supplements Fact Sheet for Consumers

Probiotics

Role of Probiotics: Probiotics help the bacteria in your gut (large intestines specifically). The gut microbiome is still being understood, but this colony of bacteria – is believed to affect our digestion and overall gut health. There are potential additional benefits, but this is still unclear. We can get probiotics from fermented foods, including yogurt.

Proven Benefits of Supplements: This is like the multivitamins – each supplement is different. And, despite claims, supplements have little known or proven benefits. While there may be an impressive number of microorganisms with individual products (often listed in the billions), this number doesn’t have much meaning other than impressive. This is because of two things: 1) we don’t know what the optimal amount is, and 2) the amount isn’t as significant as the type of microorganisms. Here is the deal – while there are some suggested benefits, such as helping with IBS or other GI distress and weight, there is not enough evidence (if any) suggesting these are benefits.

Potential Risks: Fermented foods are great; however, some probiotic supplements may contribute to infection, especially in infants and people with compromised immune systems. We could tell you if we knew which ones, but we don’t.

Does it work? If you are healthy, you may not get much benefit, if any. Choose fermented foods over supplements.

Key Message: Choose foods high in probiotics and prebiotics (vegetables are a good source of prebiotics). Save your money and choose foods.

Learn more: Probiotics Fact Sheet for Consumers

Vitamin C

Role of Vitamin C: Ascorbic acid (aka vitamin C) helps with collagen production, helps absorb iron, is an antioxidant, and helps the immune system do its job.

Proven Benefits of Supplements: well, it can correct a deficiency, but considering adults need between 75-90 mg of vitamin C (add 35 mg if you smoke), which is quickly consumed from food, having some citrus or vegetables can usually take care of the deficiency. The recommended amount isn’t anywhere close to what most people think. Supplements often have 2-10 times that amount.

Supplemental vitamin C doesn’t have proven benefits to reduce the risk of cancer – a diet high in fruits and vegetables does.

Supplemental vitamin C doesn’t have proven benefits to reduce the risk of heart disease – a diet high in fruits and vegetables does.

Supplemental vitamin C doesn’t reduce the risk of getting the common cold. It may help reduce the length and severity – marginally.

Potential Risks: this is a water-soluble vitamin, so we can’t store it – excess will tend to be excreted in the urine. However, with high doses of supplements (the Upper Limit is 2,000 mg), then it can cause distress – nausea, cramps, and diarrhea. It also may interfere with some cancer treatments. So, if this is you, check with your healthcare provider/cancer team on whether this is okay. Don’t go off the recommendation of a friend.

Does it work? Again, what does “work” mean to you? Yes, most vitamin C supplements do indeed have vitamin C. However, considering how much you need vs what you eat, getting your vitamin C from food should not be an issue. Have a potato, broccoli, or even some strawberries.

Key Message: There are plenty of food sources of vitamin C, including many fruits and vegetables and fortified foods. It won’t cure your cold or even prevent you from getting a cold. And if you smoke, you do need more, but it still isn’t that much more.

Learn more: Vitamin C Fact Sheet for Consumers

While I chose five supplements here, there are plenty more that you may wonder about. You can get more information from the National Institutes of Health Office of Dietary Supplements Dietary Supplement Fact Sheets.

The key message for all of this is to check why you are taking any specific supplement, whether that reason is valid, and whether you are getting a benefit from taking that supplement.

Check with your healthcare provider or a Registered Dietitian Nutritionist like me for more information.

Next are some sports nutrition supplements that people look to for helping their athletic performance and recovery.