Sweet Potato and Yam – Is There a Difference?

Sweet Potato and Yam - Is There a Difference?

Sweet potatoes and yams are becoming more popular, as evidenced in restaurant fare with the current trend of ‘sweet potato fries’. Most people know that both sweet potatoes and yams are root vegetables that are good for us. We tend to use the two names interchangeably – but are sweet potatoes actually different from yams? If so, what is the difference? Is one healthier than the other? Let’s dig into the nutritional profile of each of them.

 

Sweet potatoes

Even though sweet potatoes and yams look very similar, sweet potatoes belong to the Convolvulaceae plant family, which is completely different from yams.

Interesting sweet potato trivia:

  • Sweet potatoes originated in Central and South America.
  • They are one of the oldest vegetables in the world. Evidence suggests they were consumed in prehistoric times, some 10,000 years ago.
  • There are somewhere around 400 different varieties of sweet potato which include several colors of flesh, such as orange, purple, cream/white and pink.
  • Orange flesh sweet potatoes are the most common.
  • The Convolvulaceae plant family have two embryonic leaves and are considered dicotyledons.

Nutritional profile and health benefits: Sweet potatoes contain

  • anthocyanins, which have both antioxidant and anti-inflammatory properties are found in the purple flesh variety.
  • sporamins, a unique storage protein which also contains
  • a high amount of vitamin A – an antioxidant and an anti-inflammatory, which means it protects the cells by neutralizing free radicals and it helps the body deal with inflammation. Vitamin A is also beneficial for mucous membranes, eyes and skin.
  • natural sugars that release into the blood stream at a slow rate, which keeps the blood sugar even and stabilized. The sweetness of this vegetable could also help satisfy a person’s sweet craving.
  • many vitamins:
    • Vitamin C – an antioxidant (protects cells from free radical damage); helps the body absorb iron; supports the formulation of collagen which is needed for growth and repair of tissues and cells.
    • Biotin (Vitamin H) – a coenzyme that supports healthy metabolism, nerves, cells, skin, and digestive tract.
    • Vitamin B1 (Thiamin) – important for mucous membranes, the heart, muscles and the nervous system.
    • Vitamin B2 (Riboflavin) – necessary for nerves, blood cells and hormone regulation.
    • Vitamin B3 (Niacin) – helps the nervous system and digestion; helps decrease cholesterol and triglycerides (a type of fat in the blood).
    • Vitamin B5 (Pantothenic Acid) – important for the metabolism of fat, protein and carbohydrates.
    • Vitamin B6 (Pyridoxine) – important for hair, skin and blood cell formation; reduces levels of homocysteine in the blood which have been linked to heart disease.
  • several minerals:
    • Manganese – a vital component of collagen which supports bones, skin, hair, and nails; helps control blood sugar.
    • Magnesium – helps the body deal with stress by promoting relaxation, calmness and mood. It is also important for enzyme production and helps the heart, muscles, bones and brain function.
    • Copper – important for healthy blood, strong tissues and energy; works with iron to build red blood cells.
    • Phosphorous – works with calcium for healthy teeth and bones; helps nerve function and kidney function.
    • Potassium – helps to regulate water and mineral balance in the body; beneficial for healthy blood pressure and the heart.
  • a high amount of beta-carotene, an antioxidant the body turns into Vitamin A. Consuming a small amount of healthy fat with the sweet potato helps the body to absorb the beta-carotene. Beta-carotene is typically found in the bright colored vegetable and fruit pigments – the bright rainbow colors.
  • a lot of fiber – necessary for healthy digestion and helpful in keeping blood sugar balanced (not spiking and not crashing).

Cooking sweet potatoes:

Interesting studies that have been done comparing steaming, boiling and baking sweet potatoes have shown the following:

  • Boiled sweet potatoes are better when it comes to the effect on blood sugar, as they tend to have a lower glycemic impact.
  • Steaming sweet potatoes has been shown to maximize the nutritional benefits. It deactivates peroxidase enzymes that can interfere with the anthrocyanins. This leaves the antioxidant and anti-inflammatory properties intact. Steaming takes less time than the other cooking methods.

 

Yams

It can be difficult to distinguish yams from sweet potatoes because they can be very similar when it comes to skin color, size and color of the flesh. Sweet potatoes are more common than yams. Yams belong to a completely different plant family than sweet potatoes – the Dioscoreaceae plant family.

Interesting yam trivia:

  • Unlike sweet potatoes, yams must be cooked before being eaten because they can be toxic if consumed raw.
  • Yams are indigenous to Asia and Africa and are a tropical vegetable.
  • The name yam comes from the West African word ‘nyami’ which means ‘to eat’.
  • Yams can grow to a large size – much larger than sweet potatoes.
  • Yams and other members of the Dioscoreaceae plant family are monocotyledons, which means they have one embryonic seed leaf.

Nutritional profile of yams: The nutritional profile and health benefits are similar between yams and sweet potatoes. The benefits of the first three bullet points below are listed under the nutritional profile of sweet potatoes, above.

Yams contain:

  • a small amount of beta-carotene (much less than sweet potatoes).
  • a high amount of fiber (just like sweet potatoes).
  • some of the same vitamins and minerals as sweet potatoes:
    • B Vitamins: B1 (Thiamin), B2 (Riboflavin), B3 (Niacin), B5 (Pantothenic Acid), B6 (Pyridoxine), and Vitamin C.
    • Minerals: manganese, copper, phosphorous and potassium.
  • Some vitamins and minerals that sweet potatoes do not contain:
    • Calcium – which is necessary for our bones and teeth
    • Iron – a necessary component of the blood; helps transport oxygen throughout the body via the blood.
    • Vitamin B9 (folic acid) – important in red blood cell formation; helps nervous system functioning; helps lower homocysteine levels in the blood thereby protecting the heart.

Cooking yams: Yams can be roasted/baked, boiled, or steamed (same as sweet potatoes).

So, what are the answers to the original questions? Are sweet potatoes actually different from yams? Yes, they are different:

  • Even though they look similar, they actually belong to different plant families.
  • Yams originated in Africa and Asia whereas sweet potatoes originated in Central and South America.
  • Yams are a tropical vegetable and require a warmer growing temperature than sweet potatoes.
  • Yams can grow larger than sweet potatoes.

Is one healthier than the other? Although sweet potatoes and yams are quite similar nutritionally, sweet potatoes are generally considered to be healthier. There are some slight nutritional differences. Yams contain less beta-carotene and slightly less vitamin A than sweet potatoes. However yams contain some nutrients that are not in sweet potatoes: calcium, iron and vitamin B9 (folic acid).

Sweet potatoes are more common in our marketplace than yams, and they are a great vegetable choice any time of the year. Sweet potatoes are amazingly versatile. They are not limited as a side dish for dinner – they can be used to make delicious muffins and brownies!

 

Informational Resources:

The World’s Healthiest Foods 

LiveScience

Nutrition and You

Mercola.com Food Facts

The Globe and Mail

 

Copyright © 2015 Cathy Ormon Health Coach. All rights reserved.