I’ve never been a regular vitamin taker and that’s for a few reasons. First, I just didn’t know what vitamins to take. And second, I didn’t want to waste my hard-earned money on vitamins that I wasn’t sure would do anything for me. So when I was invited to try out Arivale’s coaching and data program, I was excited to finally answer the question: what vitamins should I take?

Before I get into it, Arivale’s programs do way more than help you find our what vitamins your body needs. It’s a comprehensive program that gives you one-on-one health coaching, progress tracking, and genetic data analysis from saliva and blood samples. Their program finds out how your body’s predispositions, genes, and lifestyle affect your health and your coach helps you come up with a plan to achieve goals that your set for yourself.

I learned so much about myself through this program and there were so many “ah ha” moments where I was able to correlate events from my life to markers in my health. All pretty cool stuff! But for the purpose of this article, let’s focus in on supplements and vitamins.

I was paired up with registered dietician nutritionist and Arivale coach Lauren Leedy who helped make sense of all the data my saliva, blood, and stool sample tests came back with. Here’s what she had to say about guessing about what vitamins you should take:

“Comprehensive blood work can be very helpful at pointing to deficiencies or nutrient gaps in an individual’s body,” says Leedy. “While I always recommend taking a food first approach, a person’s dietary patterns or restrictions can certainly warrant the use of a supplement.”

Leedy adds that taking supplements without testing or the guidance of a professional can potentially be harmful as well as a waste of time and money. In fact, she’s found that many of the Arivale members she works with often reduce the number of supplements they take as they learn more about their health through the program.

As for me, I didn’t take any supplements prior to working with Leedy at Arivale. But as my test results came back in, I found I was deficient in omegas and vitamin D. I wasn’t surprised about the omegas because I don’t regularly consume much of the food you get them from like fish, flaxseeds, chia seeds, and more. Omega-3s and omega-6s are beneficial because they can help prevent heart disease and inflammation as well as support cognitive health and so much more.

I like to blame my seafood-hating boyfriend for my lack of omegas. It’s all your fault Will!

As for the vitamin D, at first I wasn’t surprised. I’m a fair, red-haired lass and I tend to avoid the sun like the plague. However, despite my best efforts, I still do spend a good amount of time outside in the sun (the main way we humans get vitamin D), so I didn’t think it would be a problem.

It turns out I can blame my genes for this one. “You have a form of the GC genetic variant which provides the instructions for the carrier protein for vitamin D in the blood,” explains Leedy. “This carrier protein protects vitamin D from breakdown. As a result, you are more likely than others to have low vitamin D levels in your blood. This may partially explain why you initially presented with low levels, and needed to use a supplement.”

Vitamin D has been found to be critical for bone health and having low levels is associated with cardiovascular disease and cancer. Yikes!

Luckily, Leedy recommended a supplement from Nordic Naturals ($25) to help boost my omegas and vitamin D levels. I’ve added it to my daily routine, and six months later, I’m happy to report that there was a huge increase in my levels. See the graph below as evidence!

Since tests and a professional are recommended before you start taking supplements, I asked Leedy if there were any supplements or vitamins that would benefit everyone. Her answer: vitamin D.

“Vitamin D stands out as the one nutrient that is very difficult to obtain from our diets,” says Leedy. “If [an Arivale] member presents with low blood levels, I almost always recommend a supplement. At the same time, I do have members that find out they actually have perfectly normal levels, and therefore don’t need to supplement. This is a perfect example how getting an inside view of your body can be invaluable.”

After seeing such positive results, I’ll continue to take my omega/vitamin D supplement. I love that I have concrete evidence that I need it and am not wasting my time and money.

Also, this story isn’t sponsored, but should you be interested in trying out Arivale for yourself, they have a really great special going on right now. You can try their “3 Month Health Quick Start” for $297 ($597 normally).