1.3: Science and Nutrition Today

The early 1900s marked the golden age of nutrition research, generating great excitement among scientists—much like the excitement in today’s golden age of biotechnology. For their discoveries relating to vitamins, scientists won a cluster of Nobel Prizes in 1928, 1929, 1934, 1937, 1938, and 1943. The era of rapid progress in identifying vitamins and nutritional deficiency diseases was essentially complete by 1948 when vitamin B₁₂ was discovered (it was the last vitamin discovered).

Despite the discoveries of “simple cures” for nutritional deficiencies, these diseases are still widespread throughout the world. The news brings us vivid pictures and stories of people dying from starvation (“calorie deficiency”).

Fewer of us are aware that serious nutritional deficiency diseases such as beriberi are still common in many parts of the world, or that vitamin A deficiency is still a major cause of blindness in children. Barriers such as poverty and politics still lie between what is scientifically possible and what has been achieved in preventing these diseases.

In the U.S., the major nutrition problem is no longer dietary deficiencies, but an “exercise deficiency” combined with excesses in eating. This situation is an anomaly in human history. We evolved mostly during the nearly 500,000 years that make up the Stone Age.

Life was hard. People didn’t grow crops or raise livestock; they hunted and gathered their food. Famines were common, and hard physical labor was required for survival.

The harsh environment selected for those who stored fat efficiently and relinquished it sparingly, preferred fatty foods (concentrated sources of calories) and salty foods (salt was scarce). Even with ample body fat, feeling hungry every few hours drove the continual hunting and gathering that was essential for survival. These same traits now work against us when we have a constant and abundant supply of food and little need to exercise, leading to a higher risk of obesity, diabetes, heart disease, osteoporosis, and the like (Figure 1.2.1, 1.2.2).

Much of nutrition research now focuses on obesity, obesity-related diabetes, and the effects of diet on chronic diseases like heart disease, cancer, and osteoporosis. Heart disease is the leading cause of death in this country, cancer is the second, and osteoporosis is a common cause of disability in the aged. Scientific progress is relatively slow due to the complexity of these diseases. In stark contrast to an acute disease like scurvy, chronic diseases develop over many years, involve many genetic and environmental factors, and aren’t easy to cure.

Many chronic diseases have common risk factors, thus simplifying health advice. Smoking, for example, not only raises the risk of lung cancer, but also that of heart disease, chronic bronchitis, emphysema, and cancer of the esophagus, bladder, and pancreas. Diet plays an important role in many diseases, such as heart disease, chronic liver disease, and some cancers. The American Heart Association, American Cancer Society, and other agencies that evaluate the scientific evidence relating to diet and health all give similar advice.

Scientific information is now disseminated quickly—a far cry from the communication of

Figure \(\PageIndex{3}\): Average life expectancy, ages 60-90

what Cartier and Lind learned about scurvy. The New England Journal of Medicine, for example, has subscribers worldwide, is published weekly, and is available online. It’s but one of thousands of scientific research journals published throughout the world.

Scientific information is transmitted faster than ever. Physicians often hear about a journal article in the news before they get a chance to read the article themselves. Of course, misinformation also is transmitted faster. Much nutrition nonsense and quack cures for all sorts of diseases, real and imagined, are all there online.

Online information also has fanned the already huge interest in dietary supplements. Food and medicine now overlap, with functional foods like Benecol (a margarine used to lower blood cholesterol) and nutraceuticals (nutrients used as pharmaceuticals/medicine).

Dietary supplements include a wide array of substances, from vitamin pills to herbs to hormones, so it’s hard to make generalizations. But one important generalization to keep in mind is that, unlike drugs, dietary supplements don’t have to be proven safe and effective before being sold. Testing for safety, effectiveness, purity, etc., is expensive and time-consuming. Thus, there’s a huge economic advantage to calling something a dietary supplement rather than a drug, though it can be hard to tell which is which. For example, pills of thyroid hormone (made by the thyroid gland) are sold as a drug, yet pills of the hormone melatonin (made by the pineal gland) are sold as a dietary supplement.

Sellers of dietary supplements often provide a distorted view of their products. The more objective information from scientific studies often comes in soundbites that can inadvertently push the products. You hear in the news that a study found that people with higher blood levels of beta-carotene (usually from eating a lot of fruits and vegetables) have a lower risk of cancer. You’re not sure what beta-carotene is, worry if you get enough, so you run out to buy a bottle. (Subsequent controlled studies of beta-carotene pills didn’t show a lower cancer risk.) There’s a lot behind soundbites that we should know before acting on them.