When choosing which supplements to add to your daily routine, sometimes you need to start from within and take a look at what your body is already ingesting, and see what it needs more of.

Of course, that will start with knowing exactly what is going on within your body, and there’s a lot. “2 to 4 pounds of who you are when you step on the scale are the friendly, health-promoting bacteria that live in your digestive tract,” says Sarah Morgan, founder and CEO of Buddies In My Belly and a functional nutrition expert who uses food and nutrients to optimize gene expression and help individuals with complex health issues.

Healthy bacteria are our buddies that live in our belly, and they’re our biggest health allies, and has been shown to play a role in almost every aspect of human health, from brain health and mood regulation, immunity, healthy skin, as well as the health of the heart, digestion, inflammatory support, hormonal regulation, the absorption of nutrients, and excretion of wastes.

“The most important supplements women need to add to their diet in every decade — and the ones that provide the biggest bang for your buck — are probiotics and prebiotics, which are like food for the buddies),” says Morgan. A good probiotic will have prebiotics added to it, Morgan explains.

If you have healthy bacteria in your digestive tract, not only will you digest and absorb the nutrients from your food at a higher rate, but these bacteria also make nutrients. Yes, that’s right. “Many different types of probiotics have been shown to make B vitamins, vitamin K, and several other nutrients crucial to our health,” says Morgan. It’s like a free vitamin shop in your belly!

As we get older, our priorities change and while skin health may be big in our 20s, fertility becomes more important in our 30s, and then things change again as we age. “In your 40s and want to keep the weight off and balance your hormones, in your 50s and starting to think about brain health and heart health, or your 60s and want to stay ageless, healthy buddies equal a healthy body,” says Morgan. And a healthy microbiome reduces the need for so many of the supplements on the market and puts more money in your pocket.

It is also important to note there are many things that help the bacteria and also some things that hurt. Focusing on a diet high in plant foods that are rich in prebiotic fiber ensures that you’re feeding the bacteria in your belly and keeping them happy and healthy. Other lifestyle habits, like stress management, adequate sleep, time outside, movement, and drinking clean water are important too. “Eating a diet that’s high in processed foods, sugar, and toxic fats, and low in fiber will hurt the buddies and feed the bad bugs like yeast that can cause different health problems,” says Morgan.

Your 20s
“During this decade, your lifestyle may prevent you from having the best diet, so you may be missing out on some key nutrients. Therefore, I recommend a multivitamin,” says the New York City-based cosmetic dermatologist Dr. Sejal Shah of SmarterSkin Dermatology “I also recommend an iron supplement or iron-rich foods, since iron deficiency is also common during this decade. Taking vitamin C with the iron helps improve its absorption. Lastly, folic acid is important if you’re planning on having children, as it can reduce the risk of neural tube related birth defects,” says Dr. Shah.

LOLA’s daily supplement is loaded with vitamins and minerals that support a healthy menstrual cycle, and this is a great time to start taking it.

Your 30s
In this decade, add vitamin D. “While confirmatory data is still needed, it’s been suggested that vitamin D deficiencies can play a role in a number of different conditions. Many people are deficient or on the low end of normal, so supplementing is important,” says Dr. Shah. “I also recommend B vitamins and probiotics, as well as periodically taking an herbal supplement that can support the adrenals — the ‘stress’ glands,” says Shah.

Also, focus on folate. “Many women are trying to get pregnant in their early 30s and in order to ensure a healthy baby with no issues of cleft palate or spina bifida, shoot for 400 micrograms of folate daily until pregnant, and then increase to 600 micrograms,” says Dr. Lisa Davis, the chief nutrition officer at Terra’s Kitchen.

Your 40s
The body has a harder time absorbing the vitamin B12 as we age, and this is especially true among vegetarians. “Shoot for 2.4 milligrams of B12 for healthy blood and nerve cells, as well as a healthy metabolism,” says Dr. Davis.

Your 50s
As you enter your 50s, start taking calcium and other supplements that can maintain bone and joint health. This is the time to make sure to exercise regularly so to keep joint health and energy levels strong.

But that doesn’t mean that focusing on sexual health stops now. It goes on. “Sexual health is important at any age. Discuss it with your doctor and review supplement options — like maca, Ashwagandha, or oyster extract — for ways to support passion and sexual health,” says Lindsey Bristol, a registered dietitian and nutritionist who works with Swanson Health.

Your 60s
“Women in their 60s need the three amigos: magnesium (320 milligrams) and vitamin K (90 micrograms) for bone and heart health, and vitamin D (10 micrograms) which confers immunity and may be protective against some cancers,” says Dr. Davis.
Also, keep moving! Maintain your health and vitality by moving each day and making sure you eat a diet rich in whole foods that includes fresh vegetables and fruits. “Fiber helps promote regularity, especially as we age, and get us plenty of brain-boosting nutrients like omega-3 fatty acids, B vitamins, curcumin (which is found in turmeric), and acetyl-L-carnitine,” says Bristol. “Keep supporting your joints with glucosamine, chondroitin, and MSM. Our joints become stiffer and less mobile as we age,” says Bristol.

70s
Focus on getting enough protein to maintain lean muscle mass. “An easy way to do this is to add a nutritional shake to your diet that’s 15 to 20 grams of protein,” says Dr. Davis. Peanut butter and boiled eggs are another way to get in additional protein.

80s
As you age, protect your health by making sure to include omega-3 fatty acids containing EPA and DHA to protect against dying from heart disease or strokes. “1 gram of fish oil capsules containing 465 milligrams of EPA (a type of omega-3 fatty acid) and 375 milligrams of DHA (another type of omega-3 fatty acid) have been shown to lower high triglyceride levels in adults,” says Dr. Davis. Be careful not to get too much because it may increase the risk of bleeding.

Aly Walansky is a NYC-based writer and editor who contributes to many lifestyles publications resgularly. Follow her on Twitter and Instagram at @alywalansky