Is Low-Carb Eating Increasing Scurvy?

Eating Low-Carb? Don't Forget Potatoes, Other Foods Rich in Vitamin C

Medically Reviewed by Charlotte E. Grayson Mathis, MD on June 10, 2004

June 10, 2004 -- The ancient mariners had scurvy. And apparently, plenty of Americans today have it, too. We're not getting enough vitamin C, the main preventative for scurvy or vitamin C deficiency, researchers say. Could low-carb eating be to blame?

The report appears in the current issue of the American Journal of Public Health.

It provides results from a large nationwide survey, showing that seniors and children get the most vitamin C in their diet. However, men and women aged 25 to 44 get the least -- and are most at risk for developing scurvy.

"A considerable number of U.S. residents are vitamin C deficient," writes researcher Carol Johnston, a professor of nutrition at Arizona State University.

Other studies have shown similar results, she writes. One U.S. study shows that 18% of adults get fewer than 30 milligrams daily of vitamin C. Another study shows that up to 20% of the 13- to 18-year-old group gets fewer than 30 milligrams daily.

Because scurvy is rarely suspected, people with the symptoms -- fatigue, limping, bleeding gums, or swollen extremities -- may not be tested for vitamin C deficiency, she explains. Very often, these patients are misdiagnosed and medicated for other disorders -- not for their vitamin deficiency.

The recommended daily allowance for vitamin C is 75 milligrams for women and 90 milligrams for men. While some people get too much vitamin C in their diets, many others get too little, she says. The body excretes excess vitamin C in the urine.

With the low-carb craze, the vitamin C-rich potato -- once the centerpiece of a healthy diet -- has been pushed aside, notes Althea Zanecosky, MS, RD, a spokeswoman for the American Dietetic Association and professor of sports and nutrition at Drexel University in Philadelphia. She agreed to comment on Johnston's study.

"Potatoes are a great source of vitamin C and other nutrients," Zanecosky tells WebMD. Other vitamin C-rich fruits are also taboo for some people adopting a low-carb diet.

The Study Details

In her study, Johnston used data from health and diet surveys completed by 15,769 Americans aged 12 to 74. Each person surveyed also had his or her blood tested for vitamin C levels.

Among her findings:

  • 14% of males and 10% of females were vitamin C deficient.
  • Only 6% of 12- to 17-year-olds were deficient.
  • The adults aged 25 to 44 had the worst vitamin C levels.

Nearly one-quarter -- 23% -- of males aged 25 to 44 were vitamin C deficient, compared with 15% of 65- to 74-year-olds.

Among females, 20% of those aged 25 to 44 were deficient, whereas 13% of 65- to 74-year-olds were also vitamin C deficient.


  • Smokers were nearly four times as likely to be vitamin C deficient as nonsmokers.
  • Those who didn't take a vitamin supplement were three times as likely to be deficient in vitamin C.

Seniors are most likely to purchase and use vitamin supplements, notes Johnston. "Vitamin C consistently ranks as one of the most frequently purchased supplements," she writes.

"We showed that individuals who did not use supplements in the previous month had a greatly increased risk of vitamin C deficiency," she notes. "For many years, physicians, dietitians, and other health professionals have hesitated to discuss vitamin supplements with patients."

Seniors are also more likely to take their medicine with orange juice," says Zanecosky. "A lot of seniors buy fortified orange juice, which has vitamins C, E, D, and calcium added. Children are getting juices fortified with vitamin C."

How often does she have to say it? "Eat fruits and vegetables! We always encourage people to eat a variety. If all you eat is an apple, you won't get vitamin C."

Potatoes are low in fat and calories. "The problem is what people put on top of the potato," Zanecosky tells WebMD. "Salsa adds vitamin C, and is a low-fat, low-cal alternative to sour cream, margarine, or butter. Salsa even counts as an extra vegetable! Broccoli also has vitamin C. Broccoli with cheddar cheese over a potato -- you get calcium, vitamin C -- a lunchtime meal."

Also, ample amounts of vitamin C are found in:

  • Guava
  • Papaya
  • Mango
  • Kiwi
  • Orange juice
  • Oranges
  • Strawberries
  • Cantaloupe
  • Grapefruit
  • Pineapple
  • Potatoes
  • Cabbage
  • Broccoli
  • Tomatoes
  • Peppers

Zanecosky advises eating foods rather than relying on supplements. "The foods have many more other vitamins and minerals that you don't get in a pill," she notes. "They're low in calories, low in fat, and fill you up. Don't tell me you can't find food on this list that's good."

Show Sources

SOURCES: Johnston, C. American Journal of Public Health, May 2004. Althea Zanecosky, MS, RD, spokeswoman, American Dietetic Association; and professor, sports and nutrition, Drexel University, Philadelphia.

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