These days, it's a good thing he's got a cellphone. It's gotten awfully confusing in the dairy aisle.
Not only are there at least half a dozen brands, but the varieties are dizzying. Should Junior choose organic? Low carb? Skim or 2 percent? Goat or soy milk?
Here are some basic milk facts to help you figure out which one to put on the shopping list.
Milk -- and we refer here to cow's milk, the most commonly consumed form of milk in the United States -- is about 88 percent water.
The other 12 percent is "milk solids" -- protein, vitamins, sugar (lactose), and minerals, as well as varying amounts of fat. These proportions won't be precisely the same in every carton you buy.
"The composition of milk can vary by the breed of the cow, its diet, the time of the year, or even the time of day or the point at which she is milked," said Peter Lehmuller, director of culinary education at Johnson & Wales University in North Carolina.
In general, however, milk from any of the six breeds used in dairy farming has the same amount of calcium, other minerals, and vitamins including A, B, D, E, and K.
Most producers add additional A and D, especially in low-fat and skim varieties, because these vitamins get removed along with the fat.
How much fat is in a cup of milk? Whole milk contains 8 grams. Two-percent contains 5 grams. One-percent contains 2.5 grams. Half- percent contains 1.25 grams, while skim (non-fat) milk has less than 0.5 gram of fat.
"The most important consideration for general health is to focus on lower-fat choices regardless of whether you're looking to lose weight," said Cathy Garvey, corporate dietitian for Jenny Craig.
"Always select non-fat or low-fat. If children don't like the consistency of non-fat, 1 percent provides some richness for them."
You can also try a fat-free variety labeled "plus," which means there are added milk solids to make it taste less watery.
The only exception, Garvey added, is babies up to age 2 who are ready to switch from breast milk or formula.
"For them, whole milk is recommended because they need the fat for brain and nervous system development, and as a concentrated source of energy when they're not yet eating a large volume of food."
Garvey is concerned that many children are drinking juice or soft drinks instead of milk, so they aren't getting the benefits of milk's calcium, protein, and vitamin D.
If they don't like plain milk, offer low-fat flavored milk or drinkable yogurt. Other kids may agree to be weaned off soda with Dr Pepper/7Up's Raging Cow or Coca-Cola's Swerve, beverages that contain about 50 percent milk and come in outrageous flavors like blueberry and pina colada. But take it easy with these because they have loads of sugar and calories.
Adults are drinking less milk, too, Garvey said.
One contributing factor is the number of adults on low-carb diets, for whom milk is taboo. But now that's no excuse, with the recent introduction of low-carb dairy beverages. Garvey suggested limiting these to your cereal or coffee because although they're milk-based, they've also got additives such as artificial sweeteners, salt, and mono- and diglycerides.
"We need to incorporate milk back into the family diet. Recent studies have shown that milk may prevent colon cancer and hypertension, and dairy calcium may help with weight management," Garvey said.
She and her husband drink a non-fat supermarket brand, while their 3-year-old son prefers 1 percent.
"We buy him a national brand only because the container is more attractive," said Garvey. "There really isn't any difference [in quality]."
"I haven't noticed a difference between store brands and name brands in either drinking or cooking," said Lehmuller, whose family prefers 2 percent for its creamier taste.
Organic milk, despite its high cost, is attracting a growing number of consumers concerned about traces of hormones, antibiotics, or pesticides in regular milk. Most supermarkets stock a choice of brands.
If you want to store extra milk in the fridge or pantry, choose a "sterilized" boxed or refrigerated variety, which has a longer expiration date because it's been pasteurized at ultra-high temperatures to kill most bacteria and enzymes that cause spoilage.
But once you open the carton, Lehmuller warned, it stays fresh only as long as regular milk, or about a week.
People who cannot drink regular milk will find lots of alternatives in today's market. These include more easily digestible goat milk, acidophilus milk, and lactose-reduced cow's milk.
"Lactose-intolerant adults actually comprise the majority of the people in the world," said Lehmuller.
According to the National Digestive Diseases Information Clearinghouse, up to 50 million Americans can't digest milk sugar properly because they lack the enzyme lactase. The result is intestinal distress after ingesting dairy products. As many as 75 percent of all African-Americans and Native Americans, 90 percent of Asian-Americans, and 51 percent of the Hispanic-American population are lactose intolerant.
If you are allergic to dairy products, eat a vegan diet, object to modern dairy-farming methods, or just don't like milk, you can substitute a milk-like soy, rice, or almond beverage.
Soy is by far the most nutritious of these options, and that's why you're seeing so much of it on your supermarket's shelves and in dairy cases.
A mixture of ground soybeans and water, soy "milk" provides about the same amount of calcium, protein, and vitamins as cow's milk, without the fat or cholesterol. Unlike milk, it also provides dietary fiber and isoflavones, a plant substance that may prevent cancer.
Dairy beverage options
-- From the USDA's Internet guide, "How to Buy Dairy," and other sources