4 supplements a dietician takes to age better after weighing the pros and cons

• Nutrition expert Cynthia Thomson relies on her plant-rich diet to get most of the nutrients she needs.
• But as she's gotten older, she's started adding a few supplements into her routine.
• She bases her regimen on her own clinical history, as well as the unique holes in her diet. 

Professor Cynthia Thomson doesn't rely on supplements to stay healthy.

As a dietician, cancer researcher, and colon cancer survivor, she knows that the capsules and powders that more than 57% of Americans use regularly don't have a big impact on a person's overall health.

But over the years, as the nutrition expert has dealt with a few specific health issues, and gotten just a tad older too, she's come up with a simple regimen of four supplements she thinks may help her age just a little bit more gracefully. She's well aware that these are not magic cure-all pills or silver bullets for her longevity. But her research has shown her that they can still have some marginal, positive impact on her health, by improving some of the nutrient issues that can accompany aging, and even possibly staving off a few common age-related diseases.

"It's all based on an indication," she told Business Insider. "And then looking at my diet and going, 'I'm not going to be able to get to that level.'"

Here's the personalized, data-driven supplement regimen she's currently following.

Vitamin D

Thomson, like a lot of longevity experts, takes vitamin D. Her latest research on the subject, published on Monday, showed that consistent vitamin D supplementation among thousands of postmenopausal women like herself helped prevent a significant number of colon and breast cancer deaths. As a colon cancer survivor, she takes that research to heart.

She also noticed in some routine blood tests she did about a decade ago that her vitamin D levels had dropped, compared to where they were when she was younger. Taking 400 IUs a day seems to have moved her levels back up into "a healthy range," she said.

Calcium

Calcium is another nutrient that many scientists, including Thomson, have shown (through decades of long-term studies) can help prevent deadly cancers in postmenopausal women. While her latest research suggests some patients should be cautious about taking it — because it may increase heart disease by calcifying coronary arteries — Thomson has calculated that the benefits of calcium supplementation outweigh the risks for her.

Her history of colorectal cancer plus her diet — low in calcium-rich animal products like cheese, yogurt, and milk — have both convinced her this supplement is one worth taking, in her specific case.

"I take calcium because of the epidemiological evidence for [cancer prevention]," she said. "And I'm concerned that I'm not getting enough in my diet."

A probiotic capsule

After a strong course of antibiotics largely cleared out the diverse and important garden of microbes living inside her gut, Thomson started taking a daily probiotic pill. She suspects it helps keep her regular.

"I had a lot of irritable bowel afterwards, and I just stayed on it," she said. "It felt like it was helping."

Magnesium

Magnesium is another favorite supplement among longevity fiends. Thomson found the mineral to be a useful tool for "regularity," similar to her probiotic.

Once she reached her 60s, she also started taking a common blood pressure medication (a diuretic) which can deplete magnesium stores. That reinforced her decision to keep taking the magnesium pills. But you can also get a good dose of magnesium from foods like spinach, avocados, and bananas.

These supplements are merely an addition to her plant-heavy diet, where she gets most of her nutrients

Thomson — first and foremost — prioritizes getting enough of all of the above nutrients (and more!) through her diet.

At home, she likes to eat tofu, tempeh, kefir, salmon, nuts and seeds, as well as plenty of vegetables. It's a classic longevity platter.

"I think as we age and our kidney function begins to decline and our liver function can also decline, I just believe in plant proteins," she said. "I'm not really vegan or vegetarian 100%, but I really push a lot of vegetables."