5 Essential Vitamins You Need to Take Once You Turn 35

Flying off the handle at the littlest thing? Your hormones might be to blame. "At age 35, you start to run out of ripe eggs in your ovaries, which means you're making less progesterone," says board-certified ob-gyn Sara Gottfried, MD, author of Younger. Progesterone keeps you calm and prevents those harried moments. To keep the hormone in the right range, you need ample vitamin C, she says. Though you can eat rich sources of vitamin C—strawberries, kiwis—a higher amount has been shown to make a difference in progesterone levels.

How much to take: 750 to 1,000 mg daily, recommends Gottfried.

Magnesium may be best known for alleviating muscle spasms, but it's one mineral you won't want to overlook. "Getting enough magnesium is really important if you're a woman over 35 dealing with PMS," says Gottfried. If you're lacking, you may notice menstrual cramps, chocolate cravings, sleep problems and anxiety, says Olivia Wagner, MS, RDN, LDN, a functional medicine specialist and clinical nutritionist at Aligned Modern Health in Chicago, IL. Those symptoms sound an awful lot like PMS (or simply being stressed), but can really be due to a magnesium deficiency. What's more, magnesium also helps produce the feel-good hormone serotonin, which buoys your mood.

How much to take: Try 200 to 400 mg before bed, which Gottfried says will also help ease tension to help you sleep.

On the early end, this is the decade when the dreaded "p" word—perimenopause—could start showing up. After reaching your peak bone mass at around age 30, the "perimenopause years are really important for making strides to preserve bone health," says Wagner. While calcium is important, even more critical is vitamin D. One-quarter of women in this age group runs low in D, a vitamin that helps your body absorb calcium. If you have a family history of osteoporosis, ask your doctor if a calcium supplement is also needed, says Wagner; otherwise, turn to food sources, like green leafy vegetables or canned salmon for calcium. D is in some foods, like fortified dairy and canned sardines, but you may need a supplement to get your levels up, says Wagner.

How much to take: Aim for 1,000 to 2,000 IU daily. However, it's best to get a blood test at the doctor's office to check your levels before supplementing, as you may need a higher dose in the short-term, says Wagner.

Do you eat fish every day? Is it fatty fish, like salmon and sardines? If you're like most of us and answered no, an omega-3 supplement may be just what you need. "I think of it as helping with your hormones because it lowers cortisol levels and reduces inflammation, which is the root of many diseases, including anxiety and depression," says Gottfried. Considering women ages 40 to 59 have the highest rate of depression, according to the CDC, doing what you can to help buffer that inflammation sooner could be beneficial.

How much to take: 2000 mg per day, says Gottfried.

A few fast facts: Women are up to eight times more likely than men to have thyroid problems, and your risk increases as you age and during and after pregnancy, Wagner says. So, once you're counting 30-something candles on your birthday cake, it's time to think (more) about your thyroid. Studies show that sufficient selenium is necessary for helping to prevent thyroid disease.

How much to take: The best way to take your selenium is—surprise!—by eating two Brazil nuts per day, says Wagner. The nuts pack two to three times the recommended daily amount of selenium (55 mcg), and are a safe way to get the right amount of the mineral, that just happens to be in food form.