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Q: What are hemp hearts, and how nutritious are they?

A: Hemp hearts are the shelled seeds of the industrial hemp plant—the same plant as marijuana (Cannabis sativa) but with only trace amounts, if any, of the psychoactive compound. Though commercial hemp production is banned by U.S. law, hemp seeds (and foods made from them) can legally be sold in the U.S. and are available from several Canadian companies by mail-order and in some health-food stores.

Similar in many ways to flaxseeds, hemp seeds are rich in protein and heart-healthy polyunsaturated fats, including alpha-linolenic acid (ALA), an omega-3 fat. Though ALA is different from the omega-3s in fish oil, it has health benefits, too.

Hemp companies make all kinds of claims—that the seeds aid weight loss, help digestion and diabetes, ease arthritis, reduce inflammation, and lower blood pressure, for example—without human research to back them. One small study found that hemp seed helped relieve atopic dermatitis; two studies found it had no significant effect on blood cholesterol or other markers of cardiovascular health. Typically, websites cite unspecified studies and/or testimonials.

Hemp seeds, like all seeds, are fairly high in calories—about 80 per tablespoon. If you consume the typical recommended dose—three to five tablespoons a day—that’s 240 to 400 calories.

Eat hemp seeds if you like their nutty taste and don’t mind their somewhat hefty price (more than $10 a pound). You can add them to hot or cold cereals, yogurts, smoothies, soups, stews, and stir-fries. Just don’t believe the health claims. Another good reason to eat hemp: It’s considered an eco-friendly plant because it needs little water and can be grown without pesticides.

Q: Is exfoliating good for the skin?

A: It can be. Exfoliation, which involves removing the outer layer of dead skin cells, can make your skin look and feel better and help some skin conditions. Your skin naturally sheds this top layer about every 30 days; exfoliation simply accelerates what the skin does on its own.

Skin shedding slows as you get older, and this can result in dry, flaky—and itchy—skin. According to Dr. Linda Franks, assistant professor of dermatology at New York University Medical Center, exfoliation brings newer, healthier skin cells to the surface, which hold water better and allow moisturizer to penetrate better, and thus is a good remedy for dry skin. If you’re prone to razor rash (folliculitis), exfoliating before shaving helps unblock pores so the hairs are less likely to become ingrown. Exfoliation may also improve hyperpigmented or uneven skin tone (due to sun damage, for example).

There are two main ways to exfoliate: mechanically, using a washcloth, loofah sponge, body brush, or skin-care product that contains abrasive particles (such as almond meal or apricot seeds); or chemically, with hydroxy acids (such as glycolic acid and lactic acid), found in some over-the-counter cleansers. Chemical peels done at dermatologists’ offices—mostly for cosmetic reasons but also for sun-damaged skin—use stronger agents.

At home, you can exfoliate once or twice a week, says Dr. Franks. Scrub gently and moisturize afterwards. Don’t use anything too abrasive on your face. If you want to use a chemical exfoliant and have sensitive skin or a skin condition, talk to your doctor about which product—if any—is best for you. You don’t need expensive products. And don’t over-exfoliate. If you do it too often or too hard, you can end up with irritated and even dryer skin than before.

Q: Why do most nutrition labels list only A, C, calcium, and iron and not other vitamins or minerals?

A: The Nutrition Labeling Education Act (NLEA) of 1990 requires most foods to list calories and certain nutrients, including fats, carbohydrates, protein, and fiber, as well as vitamins A and C, calcium, and iron. Other nutrients are optional, unless a claim is made (“high in potassium,” for example) or unless nutrients are added to a food (as in enriched pasta and fortified cereals).

Why single out A, C, calcium, and iron? Health authorities considered these nutrients to be of “particular public health significance” at the time and thought that many people were at risk for deficiencies. (Listing iron also helps people with iron overload disease limit how much iron they consume.) The B vitamins niacin, thiamin, and riboflavin—listed on earlier nutrition labels—were widespread enough in the food supply that few people were thought to be at risk for deficiency anymore; listing them thus became optional.

Other nutrients, such as vitamin D and folate, were not considered major public health concerns back then, either. If NLEA were rewritten today, there would doubtless be many changes, possibly including the requirement for labels to list vitamin D and folate.

Q: Recently I saw an ad for Metamucil Strong Bones, which contains calcium as well as fiber from psyllium. I’ve read that calcium isn’t supposed to be taken with a high-fiber meal. Isn’t that true?

A: The effect of psyllium (Metamucil is one brand) on nutrient absorption is minimal, at least in a typical dose. Psyllium comes from a grain and is primarily soluble fiber. People take it as a mild, bulk-forming laxative or to help lower blood cholesterol.

Some kinds of fiber, notably wheat bran, can reduce the absorption of calcium and other nutrients. A few early studies showed that high doses of psyllium interfere with the absorption of certain minerals. But later research found that a standard psyllium dose taken immediately before a meal has no significant effect on vitamins or minerals.
Any small effect that moderate amounts of fiber may have on nutrients is not a worry, especially if your diet is nutritious.

It’s best to get as much calcium and fiber as possible from foods, since foods rich in calcium or fiber contain other important nutrients as well. Still, many Americans fall far short in both, and for them calcium and/or psyllium supplements can help fill the gap. However, this Metamucil product is an expensive way to get psyllium and calcium carbonate, both of which cost very little in generic form.

UC Berkeley Wellness Letter, August 2010