The Truth About Supplements by Svetlana Kogan, M.D.

How Functional Medicine Takes the Guesswork Out of Your Health

Svetlana Kogan, M.D.

Thirty years ago, when I was in medical school, nobody really talked about supplements. Sure, vitamin stores were starting to pop up, but most people still associated doctors with prescription meds, not vitamins. Fast forward to today, and just about everyone seems to have a cabinet—or even a bag—full of supplements they take every day. So, what changed?

A big part of it comes down to marketing. When we see something repeatedly—on TV, online, in magazines, or on billboards, it starts to feel familiar and, by extension, safe. Add a doctor in a white coat smiling and holding a bottle, and suddenly, those pills seem like the secret to good health.

But here’s the truth: randomly taking vitamins, supplements, or herbal remedies can be just as risky as popping multiple prescription drugs without medical supervision. The FDA doesn’t regulate supplements the same way it does prescription meds. That means there’s no strict oversight on where these supplements come from, how they’re made, or what’s in them. Many aren’t even manufactured in the U.S. anymore, and while prescription drugs made overseas still go through rigorous FDA testing, supplements don’t. That’s how we
end up with “natural” pills that are contaminated with heavy metals like lead, mercury, and arsenic, or made in unsanitary conditions.

Then there’s the issue of side effects. Take vitamin D, for example. It’s everywhere, and people are popping it like candy. But did you know that vitamin D is actually a hormone? And since it’s fat-soluble, your body can store it, making it easy to take too much and reach toxic levels. That’s why you shouldn’t take vitamin D blindly—get tested first, confirm a deficiency, and then use it under medical supervision.

Even something as seemingly harmless as vitamin C isn’t for everyone. If you have hemochromatosis, high doses can lead to iron overload. And if you have gastritis or acid reflux, too much vitamin C can irritate your stomach lining and make things worse.

What’s more, many supplements contain over 20 different fillers, preservatives, colorants, and binding agents. Ever wonder how all those ingredients stay together in a multivitamin pill? Gelatin is often used as a binding agent, but it doesn’t just bind the pill—it can bind your gut too, making digestion harder. Your body must work overtime just to eliminate all that unnecessary junk.

Herbal supplements come with their own set of risks. They can interfere with important prescription medications—like HIV drugs, antibiotics, and even birth control—making them less effective or completely useless. Even something as common as green tea, which is in thousands of supplements, can cause heart arrhythmia in some people.

As a functional medicine doctor, I believe that quality and purity matter. And expert guidance absolutely matters most of all. The supplement industry in the U.S. is a $30 billion business, and most of the people pushing these products—from influencers to self proclaimed doctors, to your friend who just became a “health coach” overnight—have little to no medical training. Many are just repeating what they’ve heard or read online, without truly understanding the science behind it. And unfortunately, it’s the consumer who pays the price.

One of the best ways to take supplements safely and effectively is through functional testing. Functional testing allows us to determine exactly what vitamins, minerals, or other  supplements your body actually needs. Instead of guessing, we use precise lab tests to identify deficiencies, nutrient imbalances, and even genetic factors that affect how your body processes certain nutrients. This way, you’re not just taking supplements because they’re trendy—you’re taking what your body specifically requires, in the right doses, and in the most bioavailable form.

So, how do you navigate this minefield? The key is to work with a doctor who understands supplements, herbs, and holistic treatments. A good functional doctor has already done the research, tried the best formulas, and weeded out the junk. He or she will be able to guide you based on your specific health history, lifestyle, and lab results— helping you make informed, safe decisions. After all, your health isn’t a guessing game, and neither should your supplement routine be.

The author of ‘Diet Slave No More!’, Svetlana Kogan, M.D. is a Board-Certified Internal Medicine, Holistic & Functional Medical Doctor with 25 years of experience. Her website is CustomLongevity.com