Vitamin C is a powerful antioxidant that’s found in many foods, but some exotic fruits contain it in exceptionally high amounts. Vitamin C deficiency is rare, but it can have serious health consequences. Read about the top dietary sources of vitamin C and which symptoms might signal deficiency in this post.
Vitamin C Deficiency
Symptoms
Early indications of Vitamin C deficiency are fatigue, malaise, depression, and they may manifest as a reduced desire to be physically active [1].
Scurvy (pathological Vitamin C deficiency) leads to blood vessel fragility resulting in hemorrhage, as well as connective tissue damage due to failure in collagen production, often leading to loss of teeth and tendon rupture. At worse, scurvy can lead to death [2, 3].
Other signs and symptoms of severe vitamin C deficiency include [4]:
- Poor wound healing
- Fatigue
- Weight loss
- Gum inflammation and bleeding
- Petechiae (tiny purple, red, or brown spots on the skin), ecchymosis (a type of bruise), and purpura (purple-colored spots on the skin)
- Joint pain
- Dry eyes and dry mouth
- Corkscrew hair
Clinical scurvy can be avoided by intaking as little as 10 mg of Vitamin C per day. Scurvy is extremely rare in developed countries [5].
However, mild Vitamin C depletion has been observed in 10-30 % of the presumed healthy population [5, 6].
Causes
Causes shown here are commonly associated with vitamin C deficiency. Work with your doctor or other health care professional for an accurate diagnosis.
One of the major causes of low vitamin C levels is eating a poor diet lacking in fresh fruits and vegetables. This is commonly seen in:
- Low-income individuals [7]
- Elderly individuals who eat a tea-and-toast diet [8]
- Alcoholics and drug users [9]
- People who follow fad diets [10]
- Anorexics [11]
- People with mental illness [12]
People with malabsorption issues caused by certain gut conditions (i.e., Crohn’s disease, celiac disease) are also at risk for vitamin C deficiency [13].
Low vitamin C levels can also be caused by:
- Heavy metal toxicity [13]
- Viral illnesses [13]
- Overactive thyroid gland (hyperthyroidism) [14]
- Kidney disease/failure [15]
- Cancer [16]
Certain drugs can lower vitamin C levels:
Assessing Deficiency (Vitamin C Levels)
Vitamin C levels can be measured with a blood test.
Generally, blood Vitamin C concentration of:
- <11 μM is considered to be deficient
- 11–28 μM is depleted or marginally deficient
- 28–40 μM is adequate
- > 40 μM is optimal [5]
Some researchers believe that up to 22% of the U.S. may have below adequate Vitamin C status (blood concentrations < 28 µmol/L), and about 6% of the adult population is classified as Vitamin C deficient (<11 µmol/L) [1].
Risk Factors
The following factors can significantly increase the body’s requirements for vitamin C and the risk of vitamin C deficiency [13, 17]:
- Pregnancy [18]
- Breastfeeding [12]
- Children with poor nutritional status [6].
- High fever or inflammation [13]
- Surgery [13]
- Smoking [19]
- Type 2 diabetes [20]
- Obesity [21]
- Age [22]
In addition, one study suggested that non-supplementing men aged 20-49 are particularly at risk of poor Vitamin C status [1].
Patients receiving kidney dialysis are prone to deficiency of Vitamin C [23].
Schizophrenic patients tend to have significantly lower levels of blood Vitamin C, according to limited research [24].
Genetics can also play a role. Blood Vitamin C levels differ according to polymorphisms of SVCT2 and SVCT1 [5].
Organs With the Highest Vitamin C Requirements
Vitamin C is found in high concentrations in the pituitary, adrenals, and the ovaries, but muscle, brain, and liver contain the largest stores of this vitamin. However, being water-soluble, vitamin C is not stored in large amounts in the body [25].
Absorption
Vitamin C is absorbed from the intestinal lumen and kidney tubules and then distributed throughout the organism by the bloodstream [26].
The uptake and distribution of Vitamin C in the body is under close control and primarily regulated by tissue-specific, sodium-dependent Vitamin C co-transporters (SVCT) 1 and 2, which transport Vitamin C in exchange of sodium [6].
29+ Foods High in Vitamin C
Fruits & Vegetables
Many fruits and vegetables contain plenty of vitamin C, including citrus fruits, peppers, berries, and broccoli [27].
You need 5–9 servings of fresh, minimally processed, or frozen fruit and vegetables per day to get about 200 mg of vitamin C [28].
Here is a list of foods high in vitamin C, including some little-known superfoods [12, 29, 30, 31, 32, 33]:
- Kakadu plum or Terminalia ferdinandiana (vitamin C content estimated at 2,300 to over 5,000 mg per 100 grams )–this fruit is native to Australia and is also a good source of protein, zinc, calcium, iron, linoleic acid, and other nutrients [34, 35, 36].
- Camu camu or Myrciaria dubia, a relative of guava, is a berry that grows in the Amazonian rainforest (contains from 1570 up to 3,000 mg of vitamin C per 100g). The pulp is usually dried, pulverized, and formulated into supplements [37]
- Acerola cherries (1000 to 4500 mg per 100 grams), which are also rich in diverse antioxidants like carotenoids, phenolics, anthocyanins, and flavonoids [38]
- Indian gooseberry or amla (estimated at 440 to 880 mg per 100g) [39]
- Rosehip, especially the pulp (300-1200 mg per 100 mg–large variation between different species, highest in Rosa nitidula) [40]
- Baobab pulp (over 100 mg per 100 grams)–this African superfood is also rich in calcium, protein, and various antioxidants [41, 42]
- Peppers, sweet, raw (97 mg)
- Kale (93 mg) [43]
- Kiwi (about 93 mg)
- Broccoli (91 mg)
- Brussel sprouts (85 mg)
- Persimmons, native (66 mg)
- Papaya (61 mg)
- Strawberries (58)
- Citrus fruits, including oranges and lemons (20-53 mg)
- Guava (50 mg)
- Pineapple (48 mg)
- Cauliflower (48 mg)
- Bilberry (44 mg)
- Mango (38 mg)
- Cabbage, raw (37 mg)
- Guanabana (28 mg)
- Blackberries (21 mg)
- Tamarind (18 mg)
- Arugula (15 mg)
- Cranberries (14 mg)
- Tomatoes (13-27 mg)
- Apricots (10 mg)
- Apples (4 mg)
Vitamin C is destroyed by heat and long storage times, so eating raw (or minimally processed), fresh fruits and vegetables is the only effective way to get adequate amounts of dietary vitamin C [27].
Alternative Sources
Fruits and vegetables are available to most people nowadays, even in cold regions where vegetation is sparse for long periods of time, such as in Northern Europe and Canada.
Vitamin C is also added to many foods as a natural preservative–it works to protect against oxidation [12].
Traditionally, people living in cold environments relied on so-called “alternative” sources of vitamin C that were available to them, even during the winter. These include [12]:
- Medicinal herbs (herbal teas and tinctures from rose hips, pine needles, and tree barks)
- Animal organs (raw liver and whale skin)
However, the vitamin C content in animal foods is poor. These animal sources only contain 30–40 mg/100 g (or less), while cooking the food will destroy most of its vitamin C content. For this reason, vitamin C deficiency is plausible in people on a strict carnivore diet who are not taking supplements [44].
On the other hand, vegetables, fruits, and other plant-based sources can contain up to 5,000 mg/100 g [44].
