A cup of milk contains almost a third of your daily calcium requirement. People who avoid dairy products need to plan carefully to meet that nutritional goal. (Brennan Linsley/AP)

There are more kinds of milk out there than ever — soy, almond, coconut. But just as dizzying is the array of choices for plain old cow’s milk. This milk primer can help.

Nonfat, 1 percent, 2 percent—what’s the difference?

More than you think. Eight ounces of 2 percent (reduced-fat) milk has 122 calories and five fat grams, three of them saturated; 1 percent (low-fat) has 102 calories and two grams of fat, mostly saturated. Nonfat (skim) milk is the skinniest: 83 calories and almost zero grams of fat, plus slightly more calcium than whole milk.

Isn’t the fat in whole milk actually good for me?

Whole milk has conjugated linoleic acid (CLA), which may protect against cancer and heart disease but probably is not enough to cancel out its 4.5 grams of saturated fat. Someone on a 2,000-calorie diet should get fewer than 13 grams daily. “If you drink a few glasses per day, it’s tough to keep your saturated-fat intake at that level,” says Maxine Siegel, Consumer Reports’ food-testing manager.

Why do “shelf-stable” milks have long expiration dates?

Those products undergo ultra-high-temperature (UHT) processing, which kills even more than the 99.9 percent of bacteria destroyed by high-temperature, short-time (HTST) pasteurization used for conventional and certain regional organic milks. UHT helps milk last more than a month — six months for shelf-stable boxes. (The cartons are sterile and keep out oxygen and light.) UHT changes milk proteins, giving milk a “cooked” flavor, and can slightly reduce B vitamin levels.

Is omega-3-fortified milk a smart way to get that “good fat”?

It has 32 to 50 milligrams of omega-3s per glass, a fraction of the 500 daily milligrams suggested for heart health. Also, the omegas are added in the form of flavorless fish oil or algae oil, so drinking it is like swallowing a mini-supplement with your milk. That’s not ideal. Research suggests that omega-3 supplements may not be as effective as the real thing. It’s better to have two servings of fatty fish per week, Siegel notes.

Should I opt for organic milk?

If you can afford the extra $1 or so per half-gallon, yes, Siegel says. Department of Agriculture rules require organic dairy farms to use 100 percent organic feed, no growth hormones and no antibiotics. Buying organic also supports healthful agricultural practices. Organic milk from grass-fed cows costs a little more but has slightly more CLA and omega-3 fatty acids.

What makes “creamy” skim milks such as Skim Plus so creamy?

That creaminess comes from added milk solids or filtering to remove water and some of the milk sugar. Eight ounces have about 40 more calories, three extra protein grams and 100 milligrams more calcium than regular skim but the same amount of fat.

Do you really need dairy, anyway?

Milk has about 300 milligrams of calcium per cup, a little less than a third of the amount you need daily. But some people have problems with milk. Here’s how to get your calcium . . .

If you’re lactose-intolerant: Sip lactose-free milk. It’s treated with lactase, the enzyme that breaks down lactose (milk sugar), so it doesn’t cause gas and diarrhea. Or try yogurt. It has very little lactose and is usually well tolerated.

If you just don’t do dairy: Meeting your calcium needs without it takes careful planning. To get 1,000 milligrams, you’d have to eat a cup of frozen, cooked spinach (292 milligrams); a cup of frozen, cooked collard greens (356 milligrams); three ounces of canned salmon with the soft little bones (181 milligrams); and a cup of white beans (192 milligrams) every day.

If calcium pills just seem easier: Add up the calcium in your diet and use supplements only to reach your recommended daily intake. More calcium isn’t better, and may raise your risk of heart disease without providing extra bone benefits.

Copyright 2014. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.