Most dietary sulfur is consumed as part of certain amino acids in protein-rich foods. Meat and poultry, organ meats, fish, eggs, beans, and dairy products are all good sources of sulfur-containing amino acids. Sulfur also occurs in garlic and onions and may be partially responsible for the health benefits associated with these items. Most of the body’s sulfur is found in the sulfur-containing amino acids methionine, cystine, and cysteine. Vitamin B1, biotin, and pantothenic acid contain small amounts of sulfur.

Deficiencies of sulfur have not been documented, although a protein-deficient diet could theoretically lead to a deficiency of sulfur. Low levels of cystine, and therefore possibly sulfur, were reported many years ago in people with arthritis, but this association is far from proven.

No side effects have been reported with the use of sulfur. At the time of writing, there were no well-known drug interactions with sulfur.

No recommended intake levels have been established for sulfur. Since most Western diets are high in protein, the majority of diets probably supply enough sulfur.

LPA is found in most foods that contain protein. DPA does not normally occur in food. However, when phenylalanine is synthesized in the laboratory, half appears in the L-form and the other half in the D-form. These two compounds can also be synthesized individually, but it is more expensive to do so. The combination supplement (DLPA) is often used because of the lower cost and because both components exert different health-enhancing effects.

People whose diets are very low in protein may develop a deficiency of LPA, although this is believed to be very uncommon. However, one does not necessarily have to be deficient in LPA in order to benefit from a DLPA supplement.

Depression (DPA, LPA, DLPA) Low back pain (DPA) Pain (DPA) Parkinson’s disease (DPA) Vitiligo (LPA) Alcohol withdrawal support (DLPA) Osteoarthritis (DPA) Rheumatoid arthritis (DPA)

The maximum amount of DLPA that is safe is unknown. However, consistent toxicity in healthy people has not been reported with 1,500 mg per day or less of DLPA, except for occasional nausea, heartburn, or transient headaches. When 100 mg of LPA per 2.2 pounds body weight or more was given to animals, a variety of complex problems occurred, leading two researchers to have concerns about potential toxicity of high amounts in humans. While these concerns were directed at LPA specifically, they are likely to be equally applicable to DLPA. Although no serious adverse effects have been reported in humans taking phenylalanine, amounts greater than 1,500 mg per day should be supervised by a doctor. People with phenylketonuria must not supplement with phenylalanine. Some research suggests that people with tardive dyskinesia may process phenylalanine abnormally. Until more is known, it makes sense for people with this condition to avoid phenylalanine supplementation. LPA competes with several other amino acids for uptake into the body and the brain. Therefore, for best results, phenylalanine should be taken between meals, or away from protein-containing foods. People taking prescription or over-the-counter medications should consult a physician before taking DLPA. At the time of writing, there were no well-known drug interactions with phenylalanine.

DLPA has been used in amounts ranging from 75–1,500 mg per day. This compound can have powerful effects on mood and on the nervous system, and therefore DLPA should be taken only under medical supervision. LPA has been used in amounts up to 3.5 grams per day. For best results, phenylalanine should be taken between meals, because the protein present in food can interfere with the uptake of phenylalanine into the brain, potentially reducing its effect.

EPO is found primarily in supplements. Its presumed active ingredient, GLA, can also be found in black currant seed oil and borage oil supplements. However, it is not known whether the effects of these three oils in the body are the same.

Those with premenstrual syndrome, diabetes, scleroderma, Sjogren’s syndrome, tardive dyskinesia, eczema, and other skin conditions can have a metabolic block that interferes with the body’s ability to make GLA. In preliminary research, supplementation with EPO has helped people with these conditions. There is evidence that alcoholics may be deficient in GLA, and a double-blind study suggested that alcohol withdrawal may be facilitated with EPO supplementation. Many people in Western societies may be at least partially GLA-deficient as a result of aging, glucose intolerance, high dietary fat intake, and other problems. People with deficiencies would presumably benefit from supplemental GLA intake from EPO, black currant seed oil, or borage oil.

Type 1 diabetes Type 2 diabetes Eczema Fibrocystic breast disease Osteoporosis (in combination with fish oil) Premenstrual syndrome (PMS) Rheumatoid arthritis Skin ulcers Alcohol withdrawal Atherosclerosis Attention deficit disorder Chronic obstructive pulmonary disease Intermittent claudication Irritable bowel syndrome (IBS) Multiple sclerosis Raynaud’s disease Scleroderma Sjogren’s syndrome Tardive dyskinesia

EPO has been reported to exacerbate symptoms of temporal lobe epilepsy, which can sometimes be mistaken for schizophrenia. Other nutrients are needed by the body, along with EPO, to make PGE1. Consequently, some experts suggest that magnesium, zinc, vitamin C, niacin, and vitamin B6 should be taken along with EPO. Certain medicines may interact with evening primrose oil. Refer to drug interactions for a list of those medicines.

Although many people may have inadequate levels of GLA, the optimal intake for this nutrient remains unknown. Researchers often use 3,000–6,000 mg of EPO per day, which provides approximately 270–540 mg of GLA.

Liver extracts are available as nutritional supplements in capsules and tablets.

As it is not an essential nutrient, no deficiency state exists.

Iron-deficiency anemia

No side effects or adverse reactions have been reported. Liver extracts should not be used by people suffering from iron-storage disorders, such as hemochromatosis. As the liver is a major filtering organ for many potentially toxic environmental chemicals, some doctors are concerned that consumption of liver extracts may result in increased intake of these chemicals. At the time of writing, there were no well-known drug interactions with liver extracts.

The recommended amount depends on the concentration, method of preparation, and quality of the liver extract.

Broccoli, red peppers, currants, Brussels sprouts, parsley, potatoes, citrus fuit, and strawberries are good sources of vitamin C.

Although scurvy (severe vitamin C deficiency) is uncommon in Western societies, many doctors believe that most people consume less than optimal amounts. Fatigue, easy bruising, and bleeding gums are early signs of vitamin C deficiency that occur long before frank scurvy develops. Smokers have low levels of vitamin C and require a higher daily intake to maintain normal vitamin C levels. Women with preeclampsia have been found to have lower blood levels of vitamin C than women without the condition. Women who have lower blood levels of vitamin C have an increased risk of gallstones. People with kidney failure have an increased risk of vitamin C deficiency. However, people with kidney failure should take vitamin C only under the supervision of a doctor.

Anemia (if deficient) Athletic performance (if deficient, or to reduce pain and speed up muscle strength recovery after intense exercise) Bronchitis Bruising (for deficiency) Burns (in combination with vitamin E for prevention of sunburn only) Capillary fragility Common cold/sore throat Gingivitis (periodontal disease) (for deficiency only) Glaucoma Heart attack (for deficiency) High cholesterol (protection of LDL cholesterol) Infection Infertility (male) (for sperm agglutination) Reflex sympathetic dystrophy (prevention) Scurvy Stress Sunburn (oral, in combination with vitamin E) Wound healing Asthma Atherosclerosis Athletic performance (for exercise recovery) Autism Cataracts Childhood intelligence (for deficiency) Cold sores Dysmenorrhea (plus vitamin B3 [niacin] and rutin) Endometriosis (in combination with vitamin E) Gastritis Gingivitis (periodontal disease) (in combination with flavonoids) Gout Immune function Infertility (female) Influenza Iron-deficiency anemia (as an adjunct to supplemental iron) Lead toxicity Pancreatic insufficiency Parkinson’s disease (in combination with Vitamin E) Pre- and post-surgery health (if deficient) Preeclampsia (in combination with vitamin E; for high risk only) Pregnancy support (if the diet is low in vitamin C) Schizophrenia Skin ulcers Sprains and strains Sunburn (topical, in combination with vitamin E) Type 1 diabetes Type 2 diabetes Age-related cognitive decline Alcohol withdrawal support Amenorrhea Anemia (for thalassemia if deficient) Bipolar disorder/manic depression Boils (recurrent furunculosis) Childhood diseases Chronic obstructive pulmonary disease (COPD) Colon cancer (reduces risk) Ear infections (recurrent) Eczema Gallstones Halitosis (if gum disease and deficient) Hay fever Heart attack (for those not deficient) Hepatitis High blood pressure HIV support (oral and topical) Hives Hypoglycemia Leukoplakia Low back pain Macular degeneration Menopause Menorrhagia (heavy menstruation) Morning sickness Peptic ulcer Progressive pigmented purpura (in combination with rutoside) Prostatitis (acute bacterial prostatitis, chronic bacterial prostatitis) Retinopathy (in combination with selenium, vitamin A and vitamin E) Sickle cell anemia Sinusitis Tardive dyskinesia Urinary tract infection Vitiligo

Some people develop diarrhea after as little as a few grams of vitamin C per day, while others are not bothered by ten times this amount. Strong scientific evidence to define and defend an upper tolerable limit for vitamin C is not available. A review of the available research concluded that high intakes (2–4 grams per day) are well-tolerated by healthy people. However, intake of large amounts of vitamin C can deplete the body of copper an essential nutrient. People should be sure to maintain adequate copper intake at higher intakes of vitamin C. Copper is found in many multivitamin-mineral supplements. Vitamin C increases the absorption of iron and should be avoided by people with iron overload diseases (e.g., hemochromatosis, hemosiderosis). Vitamin C helps recycle the antioxidant, vitamin E. It is widely (and mistakenly) believed that mothers who consume large amounts of vitamin C during pregnancy are at risk of giving birth to an infant with a higher-than-normal requirement for the vitamin. The concern is that the infant could suffer “rebound scurvy,” a vitamin C deficiency caused by not having this increased need met. Even some medical textbooks have subscribed to this theory. In fact, however, the concept of “rebound scurvy” in infants is supported by extremely weak evidence. Since the publication in 1965 of the report upon which this mistaken notion is based, millions of women have consumed high amounts of vitamin C during pregnancy and not a single new case of rebound scurvy has been reported. A preliminary study found that people who took 500 mg per day of vitamin C supplements for one year had a greater increase in wall thickness of the carotid arteries (vessels in the neck that supply blood to the brain) than those who did not take vitamin C. Thickness of carotid artery walls is an indicator of progression of atherosclerosis. Currently, no evidence supports a cause-and-effect relationship for the outcome reported in this study. The vast preponderance of research suggests either a protective or therapeutic effect of vitamin C for heart disease, or no effect at all. People with the following conditions should consult their doctor before supplementing with vitamin C: glucose-6-phosphate dehydrogenase deficiency, iron overload (hemosiderosis or hemochromatosis), history of kidney stones, or kidney failure. It has been suggested that people who form calcium oxalate kidney stones should avoid vitamin C supplements, because vitamin C can be converted into oxalate and increase urinary oxalate. Initially, these concerns were questioned because of potential errors in the laboratory measurement of oxalate. However, using newer methodology that rules out this problem, recent evidence shows that as little as 1 gram of vitamin C per day can increase the urinary oxalate levels in some people, even those without a history of kidney stones. In one case, 8 grams per day of vitamin C led to dramatic increases in urinary oxalate excretion and kidney stone crystal formation causing bloody urine. People with a history of kidney stones should consult a doctor before taking large amounts (1 gram or more per day) of supplemental vitamin C. Despite possible therapeutic effects of vitamin C in people with diabetes at lower intakes, one case of increased blood sugar levels was reported after taking 4.5 grams per day. Certain medicines may interact with vitamin C. Refer to drug interactions for a list of those medicines.

The recommended dietary allowance (RDA) for vitamin C in nonsmoking adults is 75 mg per day for women and 90 mg per day for men. For smokers, the RDAs are 110 mg per day for women and 125 mg per day for men. Most clinical vitamin C studies have investigated the effects of a broad range of higher vitamin C intakes (100–1,000 mg per day or more), often not looking for (or finding) the “optimal” intake within that range. In terms of heart disease prevention, as little as 100–200 mg of vitamin C appears to be adequate. Although some doctors recommend 500–1,000 mg per day or more, additional research is needed to determine whether these larger amounts are necessary. Some vitamin C experts propose that adequate intake be considered 200 mg per day because of evidence that the cells of the human body do not take up any more vitamin C when larger daily amounts are used. Some scientists have recommended that healthy people take multi-gram amounts of vitamin C for the prevention of illness. However, little or no research supports this point of view and it remains controversial. Supplementing more results in an excretion level virtually identical to intake, meaning that consuming more vitamin C does not increase the amount that remains in the body. On the basis of extensive analysis of published vitamin C studies, researchers at the Linus Pauling Institute at Oregon State University have called for the RDA to be increased, but only to 120 mg. This same report reveals that “. . . 90–100 mg vitamin C per day is required for optimum reduction of chronic disease risk in nonsmoking men and women.” Thus, the multiple gram amounts of vitamin C taken by many healthy people may be superfluous. The studies that ascertained approximately 120–200 mg daily of vitamin C is correct for prevention purposes in healthy people have typically not investigated whether people suffering from various diseases can benefit from larger amounts. In the case of the common cold, a review of published trials found that amounts of 2 grams per day in children appear to be more effective than 1 gram per day in adults, suggesting that large intakes of vitamin C may be more effective than smaller amounts, at least for this condition.

Amylase inhibitors can be extracted from several types of plants, especially those in the legume family. Currently available Amylase inhibitors are extracted from either white kidney bean or wheat.

Amylase inhibitors are not essential nutrients and are not normally produced in the body, so no deficiency is possible.

Type 1 diabetes Type 2 diabetes Weight loss and obesity

High amounts of amylase inhibitors may cause diarrhea due to the effects of undigested starch in the colon. Diabetics taking medications to lower their blood sugar should not take amylase inhibitors without first consulting a doctor. At the time of writing, there were no well-known drug interactions with amylase inhibitors.

Depending on the potency of the amylase inhibitors , typical intake is 1,500 to 6,000 mg before meals.

Dairy and red meat contain the greatest amounts of carnitine. Therefore, people who have a limited intake of meat and dairy products tend to have lower L-carnitine intakes.

Carnitine deficiencies are rare, even in strict vegetarians, because the body produces carnitine relatively easily. Rare genetic diseases can cause a carnitine deficiency. Also, deficiencies are occasionally associated with other diseases, such as diabetes and cirrhosis. Among people with diabetes, carnitine deficiency is more likely to be found in persons experiencing complications of diabetes (such as retinopathy, hyperlipidemia, or neuropathy), suggesting that carnitine deficiency may play a role in the development of these complications. A carnitine deficiency can also result from oxygen deprivation which can occur in some heart conditions. In Italy, L-carnitine is prescribed for heart failure, heart arrhythmias, angina, and lack of oxygen to the heart.

Angina Congestive heart failure (propionyl-L-carnitine) Heart attack Intermittent claudication (propionyl-L-carnitine) Anemia (for thalassemia) Attention deficit–hyperactivity disorder Chronic fatigue syndrome Chronic obstructive pulmonary disease (COPD) Erectile dysfunction (in combination with acetyl-L-carnitine) High triglycerides Infertility (male) Intermittent claudication (L-carnitine) Sprains and strains (for preventing exercise-related muscle injury) Type 1 diabetes Type 2 diabetes Athletic performance (for ultra-endurance only) Beta thalassemia major Cardiomyopathy (only for children with inherited cardiomyopathy) Chemotherapy-induced fatigue High cholesterol Liver cirrhosis Mitral valve prolapse Raynaud’s disease Weight loss

L-carnitine has not been consistently linked with any toxicity. The body needs lysine, methionine, vitamin C, iron, niacin, and vitamin B6 to produce carnitine. Certain medicines may interact with L-carnitine. Refer to drug interactions for a list of those medicines.

Most people do not need carnitine supplements. For therapeutic use, typical amounts are 1–3 grams per day. It remains unclear whether the propionyl-L-carnitine form of carnitine used in congestive heart failure research has greater benefits than the L-carnitine form, since limited research in both animals and humans with the more common L-carnitine has also shown very promising effects.

Dairy products, meats, fish, wheat, oats, and most other protein-containing foods contain tyrosine.

Some people affected by PKU are deficient in tyrosine. Tyrosine levels are occasionally low in depressed people. Any person losing large amounts of protein, such as those with some kidney diseases, may be deficient in several amino acids, including tyrosine.

Stress Depression Phenylketonuria (for deficiency) Alcohol withdrawal support Parkinson’s disease

L-tyrosine has not been reported to cause any serious side effects. However, it is not known whether long-term use of L-tyrosine, particularly in large amounts (such as more than 1,000 mg per day) is safe. For that reason, long-term use of L-tyrosine should be monitored by a doctor. Vitamin B6, folic acid, and copper are necessary for conversion of L-tyrosine into neurotransmitters. Certain medicines may interact with L-tyrosine. Refer to drug interactions for a list of those medicines.

Most people should not supplement with L-tyrosine. Some human research with people suffering from a variety of conditions used 100 mg per 2.2 pounds of body weight, equivalent to about 7 grams per day for an average-sized person. The appropriate amount to use in people with PKU is not known, therefore, the monitoring of blood levels by a physician is recommended.

Proanthocyanidins can be found in many plants, most notably pine bark, grape seed, and grape skin. However, bilberry, cranberry, black currant, green tea, black tea, and other plants also contain these flavonoids. Nutritional supplements containing proanthocyanidins extracts from various plant sources are available, alone or in combination with other nutrients, in herbal extracts, capsules, and tablets.

Flavonoids and proanthocyanidins are not classified as essential nutrients because their absence does not induce a deficiency state. However, proanthocyanidins may have many health benefits, and anyone not eating the various plants that contain them would not derive these benefits.

Chronic venous insufficiency Capillary fragility Retinopathy Sunburn Pancreatic insufficiency Varicose Veins

Flavonoids, in general, and proanthocyanidins, specifically, have not been associated with any consistent side effects. As they are water-soluble nutrients, excess intake is simply excreted in the urine. At the time of writing, there were no well-known drug interactions with Proanthocyanidins.

Flavonoids (proanthocyanidins and others) are a significant source of antioxidants in the average diet. Proanthocyanidins at 50–100 mg per day is considered a reasonable supplemental level by some doctors, but optimal levels remain unknown.

Brewer’s yeast, which has a very bitter taste, is recovered after being used in the beer-brewing process. Brewer’s yeast can also be grown specifically for harvest as a nutritional supplement. “De-bittered” yeast is also available, though most yeast sold in health food stores that does not taste bitter is not real brewer’s yeast.

Brewer’s yeast is not an essential nutrient, but it can be used as a source of B-complex vitamins and protein. It is by far the best source of chromium, both in terms of quantity and bio-availability.

High cholesterol Type 2 diabetes Diarrhea (infectious)

Side effects have not been reported from the use of brewer’s yeast, although allergies to it exist in some people. It is not related to Candida albicans fungus, which causes yeast infection. Because it contains a highly biologically active form of chromium, supplementation with brewer’s yeast could potentially enhance the effects of drugs for diabetes (e.g., insulin or other blood sugar-lowering agents) and possibly lead to hypoglycemia. Therefore, people with diabetes taking these medications should supplement with chromium or brewer’s yeast only under the supervision of a doctor. Saccharomyces boulardii is registered in Europe under the name Saccharomyces cerevisiae, though the manufacturer states that S. boulardii is not the same as brewer’s yeast (S. cerevisiae). There is a case report of a person with severely impaired immune function who, after receiving treatment with S. boulardii, developed an invasive fungal infection identified as S. cerevisiae. People with severe impairment of the immune system should therefore not take brewer’s yeast or S. boulardii unless supervised by a doctor. Certain medicines may interact with brewer’s yeast. Refer to drug interactions for a list of those medicines.

Brewer’s yeast is often taken as a powder, or as tablets or capsules. High-quality brewer’s yeast powder or flakes contain as much as 60 mcg of chromium per tablespoon (15 grams). When doctors recommend brewer’s yeast, they will often suggest 1–2 tablespoons (15–30 grams) of this high-potency bulk product per day. Remember, if it is not bitter, it is not likely to be real brewer’s yeast and therefore will not contain biologically active chromium. In addition, “primary grown” yeast (i.e., that grown specifically for harvest, as opposed to that recovered in the brewing process) may not contain GTF.