DEAR DOCTOR,

My company provides perks for involvement in its wellness program, and I’ve decided to start biking the 4 miles (with a few hills!) to work. Do you think it’s a good choice? Any advice for getting started?

— uphill both ways

DEAR UPHILL,

First, congratulations for making this positive change in your life. Cycling is a terrific activity with multiple health benefits. Exercise, in general, has been shown to help boost energy; improve mood; reduce the risk of a range of diseases, including heart disease and certain cancers; maintain a healthy weight; add to strength, agility and flexibility; and aid in sleep.

As you cycle the 4 miles to and from work, you’ll use an impressive range of muscle groups. These include the hamstrings and quadriceps, which are the two major muscles in the legs; the calf muscles; the gluteals, which are the trio of muscles that make up the buttocks; the core muscles of the abdomen; and to a lesser degree, the muscles of the upper body.

Conquering those hills will get your heart and lungs working and help build strength, stamina and endurance.

Cycling is an excellent resistance activity, which means it’s good for bones and bone density. It’s also a low-impact activity, so it’s kind to the joints. And the hundreds of tiny decisions needed to navigate a route and negotiate traffic help keep you mentally sharp. By the time you wheel into work after 30 to 45 minutes on the bike, you’ll have a nice endorphin glow with which to start your day.

The two main things to consider are conditioning and safety. If you haven’t been cycling on a regular basis, start by making sure your bike fits you properly and is in good repair. Your local bike shop can help you with that.

Start training with short rides, gradually building up until you’re comfortable with your daily commute. The goal is to improve physical conditioning and also to become comfortable on the bike and out on the roads. Age plays a role as well. Once we hit our 40s, our muscles don’t perform at the same level as in our younger days. For older riders, this means more time to build strength, and longer to recover.

The main risks of cycling come from run-ins with motor vehicles, so you want to focus on safety. Always obey the rules of the road; for instance, be sure to ride with traffic, not against, and signal your turns. A common refrain from drivers is that they didn’t see the cyclist until it was too late.

So make yourself as visible as possible with bright colors and reflective gear. In low light or darkness, make yourself known with reflectors, a white front light and red rear light on your bike, and again, reflective gear.

Remember to always — this is non-negotiable no matter how short a distance you plan to ride — wear a good helmet. It can save your life.

Vitamin B12 is vital to the body

DEAR DOCTOR,

I’m 19 years old, and I switched to a vegan diet six months ago. I’m careful about getting enough vitamin B12. However, some of my girlfriends say it’s not that important and your body makes all the B12 you need. Is that true?

— words of wisdom, let it ‘b’?

DEAR WISDOM,

This is a serious issue, and the answer is that nothing your friends are telling you about vitamin B12 is correct.

For those not familiar with the specifics, a vegan diet excludes all animal-based food. That means no meat, fish, seafood, dairy products and eggs. The restrictions also cover honey, which comes from bees, and gelatin, a protein obtained from the bones and connective tissue of animals, often cows or pigs. Because B12 is naturally available only in the major animal products that vegans don’t eat, getting enough becomes a daily goal.

So what is B12 exactly? It’s the most complex of the 12 B vitamins, and it is categorized as an essential vitamin. That means the body requires it, but doesn’t make it. Instead, B12 is produced by certain bacteria. The B12 they make gets distributed throughout an animal’s body, where it binds to proteins. When you eat an egg, drink some milk or have a burger, the process of digestion releases the B12 from the animal protein and makes it available for your body to use. The vitamin is essential to a range of vital functions.

A B12 deficiency can result in a variety of ailments. As people age, their digestive systems become less efficient at extracting the nutrient. Those with digestive issues such as Crohn’s disease or celiac disease, immune system disorders such as lupus or Graves’ disease, and those who have had gastrointestinal surgery are also at increased risk of a B12 deficiency.

So how much B12 do we need? For the average teenager and adult, the magic number is 2.4 micrograms a day. Women who are breastfeeding need 2.8 micrograms per day. The vitamin is available to vegans in vitamin supplements; fortified food products such as cereals, some plant milks and brewer’s yeast; and by prescription. Best get it daily.

If you’re not sure about your B12 status, your health care provider can check your levels with a simple blood test.

Dr. Eve Glazier, MBA, is an internist and assistant professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and primary care physician at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.

Eve Glazier, M.D., MBA, is an internist and assistant professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and primary care physician at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.

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